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Theories have been widely proposed and tested for impacts of soil nitrogen (N) on phytochemical defenses. Among the hundreds of distinct cardenolide toxins produced by milkweeds (Asclepias spp.), few contain N, yet these appear to be the most toxic against specialist herbivores. Because N- and non-N-cardenolides coexist in milkweed leaves and likely have distinct biosynthesis, they present an opportunity to address hypotheses about drivers of toxin expression. We tested effects of soil N and herbivore-damage on cardenolide profiles of two milkweed species differing in life-history strategies (Asclepias syriaca and A. curassavica), and the toxicity of their leaves. In particular leaf extracts were tested against the target enzymes (Na + /K + -ATPase extracted from neural tissue) from both monarch butterflies (Danaus plexippus) as well as less cardenolide-resistant queen butterflies, D. gilippus. Increasing soil N enhanced biomass of Asclepias syriaca but had weak effects on cardenolides, including causing a significant reduction in the N-cardenolide labriformin; feeding by monarch caterpillars strongly induced N-cardenolides (labriformin), its precursors, and total cardenolides. Conversely, soil N had little impact on A. curassavica biomass, but was the primary driver of increasing N-cardenolides (voruscharin, uscharin and their precursors); caterpillar induction was weak. Butterfly enzyme assays revealed damage-induced cardenolides substantially increased toxicity of both milkweeds to both butterflies, swamping out effects of soil N on cardenolide concentration and composition. Although these two milkweed species differentially responded to soil N with allocation to growth and specific cardenolides, leaf toxicity to butterfly Na + /K + -ATPases was primarily driven by herbivore-induced defense. Thus, both biotic and abiotic factors shape the composition of phytochemical defense expression, and their relative importance may be dictated by plant life-history differences., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Phosphate-solubilizing bacteria (PSB) can solubilize soil fixed phosphorus (P) to plant available forms. In previous studies, the mechanisms of inorganic phosphate solubilization by PSB mostly focused on the acidolysis of organic acids. Here we screened a highly efficient PSB, Advenella kashmirensis DF12, with the maximum P solubilization of 590 mg L - 1 at 6 days. In addition to its P solubilizing ability, DF12 also showed a tolerance to pH from 5 to 10 and a nitrogen fixation potential. The multiple functions of DF12 and its wide adaptability to various environmental conditions make it a promising biofertilizer candidate. The combined analysis of extracellular metabolites and intracellular metabolome data revealed that the production of organic acid (mainly gluconic acid) is not the only mechanism of P solubilized by DF12, the solubilized P content was not correlated with the gluconic acid concentration but was in a highly significant positive correlation with proton concentration, extrusion of proton during NH 4 + assimilation plays a key role in phosphate solubilization. Moreover, the contribution of NH 4 + assimilation to phosphorus solubilization is generally present in PSB. Therefore, we proposed that applying ammonium fertilizer in P-deficient soil is more appropriate, it can not only supplement nitrogen fertilizer, but also enhance P use efficiency, which contributes to worldwide fertilizer use reduction and efficiency improvement., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The biotechnological potential for agricultural applications in the soil in the thawing process on Whalers Bay, Deception Island, Antarctica was evaluated using a metagenomic approach through high-throughput sequencing. Approximately 22.70% of the sequences were affiliated to the phyla of the Bacteria dominion, followed by 0.26% to the Eukarya. Proteobacteria (Bacteria) and Ascomycota (Fungi) were the most abundant phyla. Thirty-two and thirty-six bacterial and fungal genera associated with agricultural biotechnological applications were observed. Streptomyces and Pythium were the most abundant genera related to the Bacteria and Oomycota, respectively. The main agricultural application associated with bacteria was nitrogen affixation; in contrast for fungi, was associated with phytopathogenic capabilities. The present study showed the need to use metagenomic technology to understand the dynamics and possible metabolic pathways associated with the microbial communities present in the soil sample in the process of thawing recovered from the Antarctic continent, which presented potential application in processes of agro-industrial interest., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The current study was designed to investigate the effect of dried orange pulp inclusion (OP diet), natural zeolite addition (Z diet), or both (OPZ diet) compared to control (CON diet) on digestibility, growth performance, nitrogen utilization, blood biochemical, antioxidative status, and cecum microbiota of growing rabbits. Seventy-two V-line male rabbits (6 weeks old) were divided into 4 balanced experimental groups. Results showed that administration of dried orange pulp or zeolite especially the OPZ diet significantly improved nutrient digestibility and nutritive values. Rabbits fed the experimental diets (OP, Z, or OPZ) recorded significantly higher values of average daily gain, N-retention, and N-balance compared with those fed the CON diet. Data on blood biochemical, showed non-significant differences in globulin concentrations, and significant decreases in levels of cholesterol, LDL (low-density lipoproteins), triglycerides, and MDA (malondialdehyde) as an antioxidant biomarker with OP, Z, or OPZ diets. Moreover, the incorporation of orange pulp or zeolite in diets significantly decreased the cecal count of E. coli, with no significant difference in total bacterial count among the experimental groups. It could be concluded that a combination between dried orange pulp and natural zeolite in the diet can enhance the growth performance, antioxidant and health status of rabbits., (© 2024. The Author(s).)

Ecoenzymatic stoichiometry can reflect the ability of soil microorganisms to acquire energy and nutrients and to determine their response to environmental stresses. However, the drivers of metabolic limitation of the moss biocrust microbiome during the ecological restoration of coal mining areas are poorly understood. Therefore, in this study, enzymatic stoichiometry modeling and high-throughput sequencing were used to simultaneously determine moss biocrust microbial metabolic limitation and its relationship with moss biocrust nutrients and arbuscular mycorrhizal fungal (AMF) diversity in five arid and semi-arid revegetation types (Hippophae rhamnoides, Amorpha fruticosa, Cerasus humilis, Cerasus szechuanica, and Xanthoceras sorbifolium) and two microbial treatments (AMF-inoculated and uninoculated). The activities of moss biocrust carbon (C)-, nitrogen (N)-, and phosphorus (P)-acquiring enzymes and organic carbon fractions in the AMF-inoculated treatment were significantly higher than those in the uninoculated control. Moss biocrust microbial community C and P limitations were observed in the five revegetation types, with lower limitation in general in the AMF-inoculated treatment. Dinitrogen-fixing plants (Amorpha fruticosa and Hippophae rhamnoides) significantly mitigated moss biocrust microbiome C and P limitation, especially in the AMF-inoculated treatment. Furthermore, partial least squares path modeling (PLS-PM) shows that moss biocrust organic carbon fractions (- 0.73 and - 0.81 of the total effects, respectively) and AMF diversity (- 0.73 and - 0.81 of the total effects) had negative effect on microbial C and P limitation, suggesting that more efficient active nutrients and AMF diversity are important factors alleviating limitation of moss biocrust microbial metabolism. This indicates that moss biocrust microbial communities under N 2 -fixing species with AMF inoculation were more stable under environmental stress; thus, AMF inoculation and/or N 2 -fixing plants may be recommended as preferred options for the ecological restoration of arid mining areas., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The complex niche of fish gut is often characterized by the associated microorganisms that have implications in fish gut-health nexus. Although efforts to distinguish the microbial communities have highlighted their disparate structure along the gut length, remarkably little information is available about their distinct structural and functional profiles in different gut compartments in different fish species. Here, we performed comparative taxonomic and predictive functional analyses of the foregut and hindgut microbiota in an omnivorous freshwater fish species, Cyprinus carpio var. specularis, commonly known as mirror carp. Our analyses showed that the hindgut microbiota could be distinguished from foregut based on the abundance of ammonia-oxidizing, denitrifying, and nitrogen-fixing commensals of families such as Rhodospirillaceae, Oxalobacteraceae, Nitrosomonadaceae, and Nitrospiraceae. Functionally, unique metabolic pathways such as degradation of lignin, 2-nitrobenzoate, vanillin, vanillate, and toluene predicted within hindgut also hinted at the ability of hindgut microbiota for assimilation of nitrogen and detoxification of ammonia. The study highlights a major role of hindgut microbiota in assimilating nitrogen, which remains to be one of the limiting nutrients within the gut of mirror carp., (© 2024. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

The N 2 -fixing trees Alnus spp. have been widely encroaching into boreal peatlands, but the nutrient responses of native vascular plants remain unclear. Here, we compared nutrient concentrations and isotope signal of six common plants (Betula fruticosa, Salix rosmarinifolia, Vaccinium uliginosum, Rhododendron tomentosum, Chamaedaphne calyculata, and Eriophorum vaginatum) between Alnus hirsuta island and open peatland and assessed plant nutrient responses to A. hirsuta encroachment in boreal peatlands. Alnus hirsuta encroachment increased nitrogen (N) concentration of leaf, branch, and stem. Despite no significant interspecific difference in branch and stem, the increment magnitude of leaf N concentration varied among species, with greatest magnitude for R. tomentosum (55.1% ± 40.7%) and lowest for E. vaginatum (9.80% ± 4.40%) and B. fruticosa (18.4% ± 10.7%). Except for E. vaginatum, the significant increase in δ 15 N occurred for all organs of shrubs, with interspecific differences in change of leaf δ 15 N. According to the mass balance equation involving leaf δ 15 N, R. tomentosum and E. vaginatum, respectively, obtained highest (40.5% ± 19.8%) and lowest proportions (-14.0% ± 30.5%) of N from A. hirsuta. Moreover, the increment magnitudes of leaf N concentration showed a positive linear relationship with the proportion of N from A. hirsuta. In addition, A. hirsuta encroachment reduced leaf phosphorus (P) concentration of deciduous shrubs (i.e., B. fruticosa, S. rosmarinifolia, and V. uliginosum), thus increasing N:P ratio. These findings indicate that Alnus encroachment improves native plant N status and selectively intensifies P limitation of native deciduous shrubs, and highlight that the N acquisition from the symbiotic N 2 -fixing system regulates plant N responses in boreal peatlands., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and N-linolenoyl-L-glutamine were originally identified in the regurgitant of Spodoptera exigua larvae. These fatty acid amino acid conjugates (FACs) are known to be elicitors that induce plants to release volatile compounds which in turn attract natural enemies of the larvae such as parasitic wasps. FAC concentrations are regulated by enzymatic biosynthesis and hydrolysis in the intestine of Lepidoptera larvae. It has been proposed that FAC metabolism activates glutamine synthetase and plays an important role in nitrogen metabolism in larvae. In this study, we identified candidate genes encoding a FACs hydrolase in Spodoptera litura using genomic information of various related lepidopteran species in which FACs hydrolases have been reported. We analyzed the importance of FAC hydrolysis on caterpillar performance with CRISPR/Cas9 knock outs. Larvae of strains with an inactive FACs hydrolase excreted FACs in their feces. They absorbed 30% less nitrogen from the diet compared to WT caterpillars resulting in a reduction of their body weight of up to 40% compared to wild type caterpillars. These results suggest that the hydrolysis of FACs is an important metabolism for insects and that FACs are important for larval growth., (© 2024. The Author(s).)

Pistachio hull (PH), a rich source of tannin, may interact with nitrogen (N) and affect N metabolism in dairy cows. This investigation aimed to assess the effects of feeding PH and two N sources (soybean meal: SBM or slow-release urea: SRU) on milk production, digestibility, and N metabolism in lactating dairy cows. The study utilized a 4 × 4 Latin square design with 12 Holstein dairy cows (body weight = 611 ± 39 kg; 84 ± 14 days in milk; 45.6 ± 5.3 kg/d milk), with treatments arranged in a 2 × 2 factorial configuration. The main factors were (1) the tannin source [without or with dried PH included at 76.5 g/kg of diet DM] and (2) two N sources [SBM vs. SRU]. Crude protein and total phenolic and tannin contents were greater, but NDF was lower in PH than in sugar beet pulp. Feeding diets containing 7.65% PH resulted in reductions in milk yield, milk urea N, and milk efficiency but milk fat and protein concentration increased. Milk yield was similar between SBM and SRU. Feeding PH in replacement to sugar beet pulp did not interact with N sources, except for feed intake, as the PH + SRU diet tended to decrease feed intake (P = 0.09). Feeding PH was also associated with decreased dry matter, crude protein, and NDF digestibility. Dry matter digestibility decreased when a portion of SBM was replaced by SRU. Feeding PH in replacement to sugar beet pulp lowered ruminal ammonia-N concentration and increased acetate-to-propionate proportion. Feeding PH vs. sugar beet pulp had no effect on N intake and N excretion in urine and milk, but it increased the amount of N excretion in feces and decreased apparent N efficiency (milk N/N intake). Alanine aminotransferase was lower in cows fed SRU only in PH- but not sugar beet pulp-containing diets. Blood creatinine was lower when SRU was included in the PH-containing diet, but the opposite was observed in diets containing sugar beet pulp. Feeding PH instead of sugar beet pulp did not affect blood urea-N but resulted in lower glucose and aspartate aminotransferase concentrations. Overall, cows fed PH in replacement to sugar beet pulp were less efficient in converting feed nutrients into milk production, likely because of its negative effect on nutrient digestion. Partial replacement of SBM with SRU had no influence on lactation productivity and urea-N concentration in milk and blood. This may imply the suitability of SRU in providing a sustained supply of N in the rumen, likely qualifying it as a viable source of N to replace a portion of SBM in dairy diets., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Key Message: The study established split-root system (SRS) in foxtail millet, and identified the molecular regulatory mechanisms and metabolic pathways related to systemic nitrogen signaling based on this system and transcriptome analysis. The growth of crops is primarily constrained by the availability of nitrogen (N), an essential nutrient. Foxtail millet (Setaria italica L.) is a significant orphan crop known for its strong tolerance to barren conditions. Despite this, the signaling pathway of nitrogen in foxtail millet remains largely unexplored. Identifying the candidate genes responsible for nitrogen response in foxtail millet is crucial for enhancing its agricultural productivity. This study utilized the split-root system (SRS) in foxtail millet to uncover genes associated with Systemic Nitrogen Signaling (SNS). Transcriptome analysis of the SRS revealed 2158 differentially expressed genes (DEGs) implicated in SNS, including those involved in cytokinin synthesis, transcription factors, E3 ubiquitin ligase, and ROS metabolism. Silencing of SiIPT5 and SiATL31 genes through RNAi in transgenic plants resulted in reduced SNS response, indicating their role in the nitrogen signaling pathway of foxtail millet. Furthermore, the induction of ROS metabolism-related genes in response to KNO 3 of the split-root System (Sp.KNO 3 ) suggests a potential involvement of ROS signaling in the SNS of foxtail millet. Overall, this study sheds light on the molecular regulatory mechanisms and metabolic pathways of foxtail millet in relation to SNS., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to evaluate the effect of replacing Tifton 85 hay (TH) with Moringa hay (MH) on the intake, apparent digestibility, ingestive behaviour, rumen parameters, serum attributes, nitrogen balance, water balance, and urinary attributes of sheep. Thus, 5 rams, ½ Dorper + ½ Santa Inês, that were 12 ± 4 months of age with an initial body weight of 32.8 ± 2.6 kg were distributed in metabolic cages in a Latin square design. The experiment lasted 85 days and was divided into five 17-day periods. The animals received rations with increasing replacement (0, 100, 200, 300, or 400 g/kg of dry matter in the total diet) of TH for MH. The forage: concentrate ratio of the diets was 40:60. Replacing TH with MH reduced (P < 0.05) the intake of organic matter, crude protein, neutral detergent fibre (NDFap), and total digestible nutrients by sheep. The apparent digestibility of NDFap and the feeding and rumination efficiencies of NDFap were reduced (P < 0.05) when MH replaced TH in the animals' diet. This replacement did not influence (P > 0.05) serum urea, total protein, creatinine, or aspartate aminotransferase in sheep. Replacing TH with MH decreased water intake and excretion (P < 0.05). In addition, nitrogen excretion via urine, urinary creatinine, and nitrogen absorption decreased (P < 0.05) when TH was replaced with MH. However, there was an increase in the sheep's nitrogen retention and urine pH. We recommend replacing 30% TH with MH in the diet of lambs because it does not compromise nutrient metabolism., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Key Message: Assembly of PUFA-attached TAGs is intimately correlated to turnover of newly formed membrane lipids in starch-deficient Chlamydomonas exposed to high light and nitrogen stress under air-aerated mixotrophic conditions. Triacylglycerols (TAGs) rich in polyunsaturated fatty acids (PUFAs) in microalgae have attracted extensive attention due to its promising application in nutraceuticals and other high-value compounds. Previous studies revealed that PUFAs accumulated in TAG primarily derived from the dominant membrane lipids, monogalactosyldiacylglycerolipid, digalactosyldiacylglycerol and diacylglycerol-N,N,N-trimethylhomoserine (DGTS), in the model alga Chlamydomonas reinhardtii. However, their respective contribution to PUFA-attached TAG integration has not been clearly deciphered, particularly in starchless Chlamydomonas that hyper-accumulates TAG. In this study, the starchless C. reinhardtii BAFJ5 was mixotrophically cultivated in photobioreactors aerated with air (0.04% CO 2 ), and we monitored the dynamic changes in growth, cellular carbon and nitrogen content, photosynthetic activity, biochemical compositions, and glycerolipid remodeling under high light and nitrogen starvation conditions. The results indicated that multiple PUFAs continually accumulated in total lipids and TAG, and the primary distributors of these PUFAs gradually shifted from membrane lipids to TAG in stress-induced BAFJ5. The stoichiometry analyses showed that the PUFA-attached TAG assembly attributed to turnover of not only the major glycerolipids, but also the phospholipids, phosphatidylethanolamine (PE) and phosphatidylglycerol. Specifically, the augmented C16:3n3 and C18:3n3 in TAG mainly originated from de novo-synthesized galactolipids, while the cumulative C18:3n6 and C18:4n3 in TAG were intimately correlated with conversion of the newly formed DGTS and PE. These findings emphasized significance of PUFA-attached TAG formation dependent on turnover of de novo assembled membrane lipids in starch-deficient Chlamydomonas, beneficial for enhanced production of value-added lipids in microalgae., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In the past few decades, the pressure of higher food production to satisfy the demand of ever rising population has inevitably increased the use synthetic agrochemicals which have deterioration effects. Biostimulants containing beneficial microbes (single inoculants and microbial consortium) were found as an ideal substitute of synthetic chemical fertilizers. In recent years, microbial consortium is known as a better bioinoculant in comparison to single inoculant bioformulation because of multifarious plant growth-promoting advantages. Looking at the advantageous effect of consortium, in present investigation, different bacteria were isolated from rhizospheric soil and plant samples collected from the Himalayan mountains on the green slopes of the Shivaliks, Himachal Pradesh. The isolated bacteria were screened for nitrogen (N) fixation, phosphorus (P) solubilization and potassium (K) solubilization plant growth promoting attributes, and efficient strains were identified through 16S rRNA gene sequencing and BLASTn analysis. The bacteria showing a positive effect in NPK uptake were developed as bacterial consortium for the growth promotion of eggplant crop. A total of 188 rhizospheric and endophytic bacteria were sorted out, among which 13 were exhibiting nitrogenase activity, whereas 43 and 31 were exhibiting P and K solubilization traits, respectively. The selected three efficient and potential bacterial strains were identified using 16S rRNA gene sequencing as Enterobacter ludwigii EU-BEN-22 (N-fixer; 35.68 ± 00.9 nmol C 2 H 4 per mg protein per h), Micrococcus indicus EU-BRP-6 (P-solubilizer; 201 ± 0.004 mg/L), and Pseudomonas gessardii EU-BRK-55 (K-solubilizer; 51.3 ± 1.7 mg/mL), and they were used to develop a bacterial consortium. The bacterial consortium evaluation on eggplant resulted in the improvement of growth (root/shoot length and biomass) and physiological parameters (chlorophyll, carotenoids, total soluble sugar, and phenolic content) of the plants with respect to single culture inoculation, chemical fertilizer, and untreated control. A bacterial consortium having potential to promote plant growth could be used as bioinoculant for horticulture crops growing in hilly regions., (© 2024. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

Key Message: Exogenous application of 24-epibrassinolide can alleviate oxidative damage, improve photosynthetic capacity, and regulate carbon and nitrogen assimilation, thus improving the tolerance of grapevine (Vitis vinifera L.) to drought stress. Brassinosteroids (BRs) are a group of plant steroid hormones in plants and are involved in regulating plant tolerance to drought stress. This study aimed to investigate the regulation effects of BRs on the carbon and nitrogen metabolism in grapevine under drought stress. The results indicated that drought stress led to the accumulation of superoxide radicals and hydrogen peroxide and an increase in lipid peroxidation. A reduction in oxidative damage was observed in EBR-pretreated plants, which was probably due to the improved antioxidant concentration. Moreover, exogenous EBR improved the photosynthetic capacity and sucrose phosphate synthase activity, and decreased the sucrose synthase, acid invertase, and neutral invertase, resulting in improved sucrose (190%) and starch (17%) concentrations. Furthermore, EBR pretreatment strengthened nitrate reduction and ammonium assimilation. A 57% increase in nitrate reductase activity and a 13% increase in glutamine synthetase activity were observed in EBR pretreated grapevines. Meanwhile, EBR pretreated plants accumulated a greater amount of proline, which contributed to osmotic adjustment and ROS scavenging. In summary, exogenous EBR enhanced drought tolerance in grapevines by alleviating oxidative damage and regulating carbon and nitrogen metabolism., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The microbial processes occurring in constructed wetlands (CWs) are difficult to understand owing to the complex interactions occurring between a variety of substrates, microorganisms, and plants under the given physicochemical conditions. This frequently leads to very large unexplained nitrogen losses in these systems. In continuation of our findings on Anammox contributions, our research on full-scale field CWs has suggested the significant involvement of the sulfur cycle in the conventional C-N cycle occurring in wetlands, which might closely explain the nitrogen losses in these systems. This paper explored the possibility of the sulfur-driven autotrophic denitrification (SDAD) pathway in different types of CWs, shallow and deep and passive and aerated systems, by analyzing the metagenomic bacterial communities present within these CWs. The results indicate a higher abundance of SDAD bacteria (Paracoccus and Arcobacter) in deep passive systems compared to shallow systems and presence of a large number of SDAD genera (Paracoccus, Thiobacillus, Beggiatoa, Sulfurimonas, Arcobacter, and Sulfuricurvum) in aerated CWs. The bacteria belonging to the functional category of dark oxidation of sulfur compounds were found to be enriched in deep and aerated CWs hinting at the possible role of the SDAD pathway in total nitrogen removal in these systems. As a case study, the percentage nitrogen removal through SDAD pathway was calculated to be 15-20% in aerated wetlands. The presence of autotrophic pathways for nitrogen removal can prove highly beneficial in terms of reducing sludge generation and hence reducing clogging, making aerated CWs a sustainable wastewater treatment solution., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The issue of heavy metal pollution such as nickel poses a significant environmental concern, exerting detrimental effects on the growth and viability of plant life. Plants have various mechanisms to effectively manage heavy metal stress, including the ability to modify their amino acid type and content. This adaptive response allows plants to mitigate the detrimental effects caused by excessive heavy metal accumulation. The aim of this study was to investigate the effect of biofertilizers on nickel accumulation, nitrogen metabolism and amino acid profile of corn (Zea mays L.) cv. 'PL438' exposed to Ni stress. After disinfecting and soaking in water for 24 h, corn seeds were primed with bacterial biofertilizers (T2: NPK + FZ), fungal biofertilizers (T3: Arbuscular mycorrhizal fungi (AMF) + Trichoderma (T)), or a combination of them (T4: NPK + FZ + AMF + T) and were cultured by the hydroponic method in completely controlled conditions. Then, they were simultaneously exposed to nickel chloride at various rates (0, 75, or 150 µM) at the three-leaf stage. They were harvested two weeks later and were subjected to the measurement of Ni content, nitrate and nitrite content, nitrate reductase activity, and amino acid profile by high-performance liquid chromatography. The results showed that the application of Ni at higher rates increased Ni, nitrate, and nitrite contents and nitrate reductase activity. The study of Ni accumulation and TF revealed that Ni accumulated in the roots to a greater extent than in the shoots and TF was < 1 in all treatments. The shoot amino acid profile showed that the treatment of Ni +2 increased som amino acids such as aspartic acid, asparagine, serine, histidine, and glycine versus the control, whereas T4 Ni +2 increased aspartic acid, glutamic acid, threonine and arginine. The change in amino acids in Ni-treated plants may play a key role in their adaptation to Ni stress. The findings indicate that biofertilizers played a crucial role in mitigating the negative impacts of Ni on corn plants through alterations in amino acid composition and decreased absorption and translocation of Ni., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Nitrogen is one of the most important nutrient sources for the growth of microalgae. We studied the effects of nitrogen starvation on the growth responses, biochemical composition, and fatty acid profile of Dunaliella tertiolecta, Phaeodactylum tricornutum, and Nannochloropsis oculata. The lack of nitrogen caused changes in carbohydrate, protein, lipid, and fatty acid composition in all examined microalgae. The carbohydrate content increased 59% in D. tertiolecta, while the lipid level increased 139% in P. tricornutum under nitrogen stress conditions compared to the control groups. Nitrogen starvation increased the oligosaccharide and polysaccharide contents of D. tertiolecta 4.1-fold and 3.6-fold, respectively. Furthermore, triacylglycerol (TAG) levels in N. oculata and P. tricornutum increased 2.3-fold and 7.4-fold, respectively. The dramatic increase in the amount of TAG is important for the use of these microalgae as raw materials in biodiesel. Nitrogen starvation increased the amounts of oligosaccharides and polysaccharides of D. tertiolecta, while increased eicosapentaenoic acid (EPA) in N. oculata and docosahexaenoic acid (DHA) content in P. tricornutum. The amount of polyunsaturated fatty acids (PUFAs), EPA, DHA, oligosaccharides, and polysaccharides in microalgal species can be increased without using the too costly nitrogen source in the culture conditions, which can reduce the most costly of living feeding., (© 2024. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

The microalgae Chlorella sorokiniana was used for the treatment of winery wastewater (WWW). Batch experiments were initially conducted to investigate how biomass acclimatization in different media, dilution of wastewater, and addition of ammonium nitrogen (NH 4 -N) affect the growth of microalgae and the removal of major pollutants. Afterwards, two sequencing batch reactor (SBR) systems were tested applying different configurations and hydraulic retention times. The biomass collected at the end of the experiments was characterized for proteins, lipids, carbohydrates, amino acid profile, and the existence of lutein, β-carotene, chlorophyll a, and tocopherols. Batch experiments showed that Chlorella sorokiniana acclimatization to urban wastewater enhanced the removal of NH 4 -N and total phosphorus (TP). The operation of a two-stage SBR system achieved COD and NH 4 -N removal equal to 85 ± 9% and 91 ± 20%, respectively, while the use of a single-stage system feeding with anaerobically pretreated WWW resulted to COD and NH 4 -N removal of 78 ± 9% and 95 ± 9%, respectively. Analyses of biomass showed higher protein content (up to 58.8%) in batch experiments with NH 4 -N addition as well as in SBR experiments. The cultivation of microalgae under SBR conditions enhanced the production of pigments and tocopherols. The maximum concentrations of 1075 mg kg -1 , 45.5 mg kg -1 , and 131.2 mg kg -1 were achieved for lutein, β-carotene, and tocopherols, respectively, in the one-stage system. Our findings suggested that Chlorella sorokiniana cultivation in WWW not only removed nutrients from WWW but also could potentially serve for the production of value-added ingredients used in food industry, cosmetics, and animal feedstock., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Soybean molasses (SBMO) is a byproduct derived from the production of soy protein concentrate, obtained through solubilization in water and alcohol. The utilization of SBMO as an animal feed ingredient shows promising potential, primarily due to its low cost and as a potential energy concentrate. This study aimed to assess the intake, digestibility, ruminal parameters (pH and ruminal ammonia - NH 3 ), nitrogen retention (NR) and microbial protein synthesis in grazing beef cattle supplemented with SBMO as a substitute for corn during the rainy season. Five Nellore (10-month-old) bulls with an average initial weight of 246 ± 11.2 kg were utilized in a 5 × 5 Latin square design. The animals were housed in five paddocks, each consisting of 0.34 ha of Marandu grass (Urochloa brizantha). Five isonitrogenous protein-energy supplements (300 g crude protein [CP]/kg supplement) were formulated, with SBMO replacing corn at varying levels (0, 0.25, 0.50, 0.75, or 1.00 g-1 g). The supplements were provided daily at a quantity of 2.0 kg-1 animal. The inclusion of SBMO at any level of corn substitution did not significantly affect the intake of pasture dry matter or total dry matter (P > 0.10). Likewise, the intake of CP and, consequently, the ruminal concentration of NH 3 did not differ among the SBMO levels. Increasing the inclusion of SBMO did not have a significant impact on NR (P > 0.10), indicating that animals receiving supplements containing 100% SBMO as a substitute for corn may perform similarly to animals receiving supplements with 100% corn (0% SBMO). Soybean molasses represents a viable alternative energy source for grazing beef cattle during the rainy season and can entirely replace corn without adversely affecting animal nutritional performance., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Key Message: Genetic dissection of a QTL from wild emmer wheat, QGpc.huj.uh-5B.2, introgressed into bread wheat, identified candidate genes associated with tolerance to nitrogen deficiency, and potentially useful for improving nitrogen-use efficiency. Nitrogen (N) is an important macronutrient critical to wheat growth and development; its deficiency is one of the main factors causing reductions in grain yield and quality. N availability is significantly affected by drought or flooding, that are dependent on additional factors including soil type or duration and severity of stress. In a previous study, we identified a high grain protein content QTL (QGpc.huj.uh-5B.2) derived from the 5B chromosome of wild emmer wheat, that showed a higher proportion of explained variation under water-stress conditions. We hypothesized that this QTL is associated with tolerance to N deficiency as a possible mechanism underlying the higher effect under stress. To validate this hypothesis, we introgressed the QTL into the elite bread wheat var. Ruta, and showed that under N-deficient field conditions the introgression IL99 had a 33% increase in GPC (p < 0.05) compared to the recipient parent. Furthermore, evaluation of IL99 response to severe N deficiency (10% N) for 14 days, applied using a semi-hydroponic system under controlled conditions, confirmed its tolerance to N deficiency. Fine-mapping of the QTL resulted in 26 homozygous near-isogenic lines (BC 4 F 5 ) segregating to N-deficiency tolerance. The QTL was delimited from - 28.28 to - 1.29 Mb and included 13 candidate genes, most associated with N-stress response, N transport, and abiotic stress responses. These genes may improve N-use efficiency under severely N-deficient environments. Our study demonstrates the importance of WEW as a source of novel candidate genes for sustainable improvement in tolerance to N deficiency in wheat., (© 2024. The Author(s).)

The Aeolian archipelago is known worldwide for its volcanic activity and hydrothermal emissions, of mainly carbon dioxide and hydrogen sulfide. Hydrogen, methane, and carbon monoxide are minor components of these emissions which together can feed large quantities of bacteria and archaea that do contribute to the removal of these notorious greenhouse gases. Here we analyzed the metagenome of samples taken from the Levante bay on Vulcano Island, Italy. Using a gene-centric approach, the hydrothermal vent community appeared to be dominated by Proteobacteria, and Sulfurimonas was the most abundant genus. Metabolic reconstructions highlight a prominent role of formaldehyde oxidation and the reverse TCA cycle in carbon fixation. [NiFe]-hydrogenases seemed to constitute the preferred strategy to oxidize H 2 , indicating that besides H 2 S, H 2 could be an essential electron donor in this system. Moreover, the sulfur cycle analysis showed a high abundance and diversity of sulfate reduction genes underpinning the H 2 S production. This study covers the diversity and metabolic potential of the microbial soil community in Levante bay and adds to our understanding of the biogeochemistry of volcanic ecosystems., (© 2024. The Author(s).)

As versatile signaling molecules, melatonin (ML) and hydrogen sulfide (H 2 S) are well-known for their roles in response to abiotic stresses. However, their cross-talk to the regulation of biochemical defence responses and secondary metabolite synthesis during salinity has received less attention. Here, the role of ML-H 2 S interplay in inducing defensive responses and the biosynthesis of essential oil compounds in summer savoury plants under NaCl treatment was investigated. NaCl treatment, by increasing Na accumulation, disrupting nitrogen metabolism, and inducing oxidative stress, lowered photosynthetic pigments and savoury growth. NaCl treatment also resulted in a decrease in γ-terpinene (10.3%), α-terpinene (21.9%), and p-cymene (15.3%), while an increase in carvacrol (9.1%) was observed over the control. ML and ML + H 2 S increased the activity of antioxidant enzymes and the level of total phenols and flavonoids, resulting in decreased levels of hydrogen peroxide and superoxide anion and alleviation of oxidative damage under salinity. ML and ML + H 2 S increased K uptake and restored K/Na homeostasis, thus protecting the photosynthetic apparatus against NaCl-induced toxicity. ML and ML + H 2 S treatments also improved nitrate/ammonium homeostasis and stimulated nitrogen metabolism, leading to improved summer savoury adaptation to NaCl stress. ML and ML + H 2 S changed the composition of essential oils, leading to an increase in the monoterpene hydrocarbons and oxygenated monoterpenes in plants stressed with NaCl. However, the addition of an H 2 S scavenger, hypotaurine, inhibited the protective effects of the ML and ML + H 2 S treatments under NaCl stress, which could confirm the function of H 2 S as a signaling molecule in the downstream defence pathway induced by ML., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We studied the effects of some nitrogen-containing, heterocyclic, and cyclic compounds on the rate of oxidative deamination of polyamines and putrescine in tissues with a high proliferation rate. For this purpose, the specific activities of the main enzymes of polyamine oxidative degradation - spermine oxidase (SMO), polyamine oxidase (PAO), and diamine oxidase (DAO) were determined using a cell-free test system from regenerating rat liver. The compounds methyl 2-(5-formylfuran-2-yl)benzoate and 2,7-bis-[2-(diethylamino)ethoxy]-9H-fluoren-9-one (and in the form of dihydrochloride) showed mainly activating effect on oxidative degradation of putrescine, spermidine, and spermine, which indirectly indicates their antiproliferative effect. Nitrogen-free compounds inhibited this process, thus exhibiting potentially carcinogenic properties. Correlations were calculated for activity of DAO, PAO, and SMO with 5 topological indices: Wiener (W), Rouvray (R), Balaban (J) in the Trinaistich modification, detour (Ip), and electropy (Ie). The highest dependence was noted for DAO and the Balaban index (R=-0.55), for PAO and the detour index (R=0.78), and for SMO and the electropy index (R=0.53). The remaining dependencies showed insignificant correlation strength., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature.)

The present study investigates the seasonal variations in leaf ecophysiological traits and strategies employed by co-occurring evergreen and deciduous tree species within a white oak forest (Quercus leucotrichophora A. Camus) ecosystem in the central Himalaya. Seasonal variations in physiological, morphological, and chemical traits were observed from leaf initiation until senescence in co-occurring deciduous and evergreen tree species. We compared various parameters, including net photosynthetic capacity (A area and A mass ), leaf stomatal conductance (gsw area and gsw mass ), transpiration rate (E area and E mass ), specific leaf area (SLA), mid-day water potential (Ψ md ), leaf nitrogen (N) and phosphorus (P) concentration, leaf total chlorophyll concentration, photosynthetic nitrogen- and phosphorus-use efficiency (PNUE and PPUE), and water use efficiency (WUE) across four evergreen and four deciduous tree species. Our findings reveal that evergreen and deciduous trees exhibit divergent strategies in coping with seasonal changes, which are crucial for their survival and growth. Deciduous trees consistently exhibited significantly higher photosynthetic rates, transpiration rates, mass-based N and P concentrations (N mass and P mass ), mass-based chlorophyll concentration (Chl mass ), SLA, and leaf Ψ md , while maintaining lower leaf structural investments throughout the year compared to evergreen trees. These findings indicate that deciduous trees achieve greater assimilation rates per unit mass and higher nutrient-use efficiency. Physiological, morphological, and leaf N and P concentrations were higher in the summer (fully expanded leaf) than in the fall (senesced leaf). These insights provide valuable contributions to our understanding of tree species coexistence and their ecological roles in temperate forest ecosystems, with implications for forest management and conservation in the Himalayan region., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Alternaria alternata is a prevalent postharvest pathogen that generates diverse mycotoxins, notably alternariol (AOH) and alternariol monomethyl ether (AME), which are recurrent severe contaminants. Nitrogen sources modulate fungal growth, development, and secondary metabolism, including mycotoxin production. The GATA transcription factor AreA regulates nitrogen source utilization. However, little is known about its involvement in the regulation of nitrogen utilization in A. alternata. To examine the regulatory mechanism of AaAreA on AOH and AME biosynthesis in A. alternata, we analyzed the impact of diverse nitrogen sources on the fungal growth, conidiation and mycotoxin production. The use of a secondary nitrogen source (NaNO 3 ) enhanced mycelial elongation and sporulation more than the use of a primary source (NH 4 Cl). NaNO 3 favored greater mycotoxin accumulation than did NH 4 Cl. The regulatory roles of AaAreA were further clarified through gene knockout. The absence of AaAreA led to an overall reduction in growth in minimal media containing any nitrogen source except NH 4 Cl. AaAreA positively regulates mycotoxin biosynthesis when both NH 4 Cl and NaNO 3 are used as nitrogen sources. Subcellular localization analysis revealed abundant nuclear transport when NaNO 3 was the sole nitrogen source. The regulatory pathway of AaAreA was systematically revealed through comprehensive transcriptomic analyses. The deletion of AaAreA significantly impedes the transcription of mycotoxin biosynthetic genes, including aohR, pksI and omtI. The interaction between AaAreA and aohR, a pathway-specific transcription factor gene, demonstrated that AaAreA binds to the aohR promoter sequence (5'-GGCTATGGAAA-3'), activating its transcription. The expressed AohR regulates the expression of downstream synthase genes in the cluster, ultimately impacting mycotoxin production. This study provides valuable information to further understand how AreA regulates AOH and AME biosynthesis in A. alternata, thereby enabling the effective design of control measures for mycotoxin contamination., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

To what extent particular plant defences against herbivorous insects are constitutive or inducible will depend on the costs and benefits in their neighbourhood. Some defensive chemicals in leaves are thought to be costly and hard to produce rapidly, while others, including volatile organic compounds that attract natural enemies, might be cheaper and can be released rapidly. When surrounding tree species are more closely related, trees can face an increased abundance of both specialist herbivores and their parasitoids, potentially increasing the benefits of constitutive and inducible defences. To test if oaks (Quercus robur) respond more to herbivore attacks with volatile emission than with changes in leaf phenolic chemistry and carbon to nitrogen ratio (C: N), and whether oaks respond to the neighbouring tree species, we performed an experiment in a forest in Poland. Oak saplings were placed in neighbourhoods dominated by oak, beech, or pine trees, and half of them were treated with the phytohormone methyl jasmonate (elicitor of anti-herbivore responses). Oaks responded to the treatment by emitting a different volatile blend within 24 h, while leaf phenolic chemistry and C: N remained largely unaffected after 16 days and multiple treatments. Leaf phenolics were subtly affected by the neighbouring trees with elevated flavan-3-ols concentrations in pine-dominated plots. Our results suggest that these oaks rely on phenols as a constitutive defence and when attacked emit volatiles to attract natural enemies. Further studies might determine if the small effect of the neighbourhood on leaf phenolics is a response to different levels of shading, or if oaks use volatile cues to assess the composition of their neighbourhood., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A bio-matrix material (BMM) system is used to pretreat swine wastewater and reduce the nitrogen (N) concentration to the tolerance range of plants in constructed wetlands. In this study, rice straw (RS), wheat straw (WS), and corn stalk (CS) were applied to treat pollutants from swine wastewater, respectively. This one year-long field experiment make up for the lack of long-term experiments and mechanistic investigations of BMM. The pollutant removal efficiency, degradation process of crop straw, and the abundance of nitrogen cycling genes were determined in different BMM systems. The results showed that the removal efficiency of COD, TN, NH 4 + , and NO 3 - was the best in the initial 6 months. Furthermore, RS and WS exhibited favorable annual removal efficiency of TN and NH 4 + , which were 32.81% and 32.99%, 35.3% and 34.97%, respectively. Moreover, the removal efficiency of COD was 30.81% in three BMM systems. Meanwhile, it was found that the dry matter (DM) degradation of crop straws was fast in the first 4-5 months. The degradation rates of cellulose, hemicellulose, and lignin were 94.19%, 94.36%, and 87.32%, respectively, in 1 year. The abundance of nitrogen cycling genes significantly increased by adding BMM, compared with CK (P < 0.05). This showed the abundance of the hzsB gene in RS was the highest, while nirK, nirS, AOA, and AOB were the highest in WS. The addition of RS and WS was better than that of CS in promoting the abundance of nitrogen cycling microorganisms. The results indicated that adding BMM could enhance the anaerobic ammonia oxidation, nitrification, and denitrification. This study not only extends our comprehension of BMM mechanisms in swine wastewater treatment but also serves as a guiding light for numerous farms in similar climate regions., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Cell components soluble in neutral detergent are a diverse group, both compositionally and nutritionally. The present study aimed to evaluate production responses, behavior (eating, ruminating, and idling), and nitrogen balance of dairy goats fed different ratios of neutral detergent-soluble carbohydrate fractions. Five multiparous Alpine does with mean ± SD initial body mass of 49.5 ± 7.9 kg and 60 days of lactation were randomly assigned in a 5 × 5 Latin square design. The treatments were the ratios of starch (starch associated with soluble sugar [StSS]) to neutral detergent-soluble fiber (NDSF) (StSS:NDSF): 0.89, 1.05, 1.24, 1.73, and 2.92. No effect was observed (P > 0.05) of StSS:NDSF on the intakes of neutral detergent fiber (NDF) and NDSC. However, DM intake showed a quadratic behavior (P = 0.049). The ingestive behavior was affected by StSS:NDSF linearly increased (P = 0.002) the feeding efficiency. The increase in StSS:NDSF caused a linear increase in fecal (P = 0.011), urinary (P < 0.001), and milk nitrogen excretion (P = 0.024). The increase in StSS:NDSF affected (P = 0.048) milk yield and net energy lactation (P = 0.036). In conclusion, dairy goats experience reduced dry matter intake and milk yield when subjected to high-NDSC diets, specifically those above 1.24 StSS:NDSF ratio. Elevated NDSC levels in the diets lead to decreased feeding time, whereas rumination remains unaffected. Nitrogen losses in goats increase linearly with high-NDSC diets, and a significant impact on nitrogen balance., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Methanol, the second most abundant volatile organic compound, primarily released from plants, is a major culprit disturbing atmospheric chemistry. Interestingly, ubiquitously found methanol-utilizing bacteria, play a vital role in mitigating atmospheric methanol effects. Despite being extensively characterized, the effect of nitrogen sources on the richness of methanol-utilizers in the bulk soil and rhizosphere is largely unknown. Therefore, the current study was planned to isolate, characterize and explore the richness of cultivable methylotrophs from the bulk soil and rhizosphere of a paddy field using media with varying nitrogen sources. Our data revealed that more genera of methylotrophs, including Methylobacterium, Ancylobacter, Achromobacter, Xanthobacter, Moraxella, and Klebsiella were enriched with the nitrate-based medium compared to only two genera, Hyphomicrobium and Methylobacterium, enriched with the ammonium-based medium. The richness of methylotrophic bacteria also differed substantially in the bulk soil as compared to the rhizosphere. Growth characterization revealed that majority of the newly isolated methanol-utilizing strains in this study exhibited better growth at 37 °C instead of 30 or 45 °C. Moreover, Hyphomicrobium sp. FSA2 was the only strain capable of utilizing methanol even at elevated temperature 45 °C, showing its adaptability to a wide range of temperatures. Differential carbon substrate utilization profiling revealed the facultative nature of all isolated methanol-utilizer strains with Xanthobacter sp. TS3, being an important methanol-utilizer capable of degrading toxic compounds such as acetone and ethylene glycol. Overall, our study suggests the role of nutrients and plant-microbial interaction in shaping the composition of methanol-utilizers in terrestrial environment., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The use of bio-nanotechnology in agriculture-such as the biological applications of metal oxide nanoparticles (NPs)-greatly improves crop yield and quality under different abiotic stress factors including soil metal contamination. Here, we explore the effectiveness of zinc oxide (ZnO)-NPs (0, 50 mg/L) foliar spraying to ameliorate the detrimental effects of cadmium (Cd) on the water transport and nitrogen metabolism in tomato (Solanum lycopersicum Mill. cv. Chibli F1) plants grown on a Cd-supplied (CdCl 2 ; 0, 10, 40 μM) Hoagland nutrient solution. The results depicted that the individually studied factors (ZnO-NPs and Cd) had a significant impact on all the physiological parameters analyzed. Independently to the Cd concentration, ZnO-NPs-sprayed plants showed significantly higher dry weight (DW) in both leaves and roots compared to the non-sprayed ones, which was in consonance with higher and lower levels of Zn 2+ and Cd 2+ ions, respectively, in these organs. Interestingly, ZnO-NPs spraying improved water status in all Cd-treated plants as evidenced by the increase in root hydraulic conductance (L 0 ), apoplastic water pathway percentage, and leaf and root relative water content (RWC), compared to the non-sprayed plants. This improved water balance was associated with a significant accumulation of osmoprotectant osmolytes, such as proline and soluble sugars in the plant organs, reducing electrolyte leakage (EL), and osmotic potential (ψ π ). Also, ZnO-NPs spraying significantly improved NO 3 - and NH 4 toxicity. Our findings point out new insights into how ZnO-NPs affect water transport and nitrogen metabolism in Cd-stressed plants and support their use to improve crop resilience against Cd-contaminated soils.+ assimilation in the leaf and root tissues of all Cd-treated plants, leading to a reduction in NH 4 + toxicity. Our findings point out new insights into how ZnO-NPs affect water transport and nitrogen metabolism in Cd-stressed plants and support their use to improve crop resilience against Cd-contaminated soils., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study evaluated three continuous grazing systems: Brachiaria Brizantha, Clitoria ternatea and naturalized pastures, complemented with commercial concentrate and C. ternatea silage on milk yield, nutrient use and enteric methane (CH 4 ) emissions. Nine multiparous cows of local Zebu breeds, with an average weight of 448 ± 87 kg, were used. The chemical composition of the food was determined. Live weight, milk production, and quality were assessed. Furthermore, serum urea, urea nitrogen, creatinine and glucose in blood were monitored, and nitrogen use efficiency were calculated. Enteric methane (CH 4 ) emissions were estimated using Tier-2 methodology. A 3 × 3 latin square experimental design was applied. The grazing systems of B. brizantha and C. ternatea had the greater live weights of 465.8 and 453.3 kg/cow, although the latter is similar to naturalized pasture. Milk production and quality were not affected by grazing system, with the exception of the non-fat solids, where the C. ternatea system was lower (102.2 g/kg) than the other grazing systems. The crude protein and N intake, and N excretion in feces and urine were lower in naturalized pasture systems (1139.0 g/day). N outputs in milk was high in the C. ternatea system (56.3 g/cow/day). The naturalized pastures systems showed the better feed use efficiency (25.7%) compared to others. Serum urea and blood urea nitrogen were greater in B. brizantha followed by C. ternatea. Enteric CH 4 emissions were indifferent among grazing systems when expressed as a percentage of greenhouse gases (7.1%). In conclusion, the grazing C. ternatea supplemented with commercial concentrate and C. ternatea silage maintains milk production and quality, reduced cow/day emissions (by 2.5%) and lowered energy losses as methane., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Utilizing monoalgal species for wastewater treatment is facing tremendous challenges owing to changing wastewater complexity in terms of physico-chemical characteristic, nutrient and metal concentration. The environmental conditions are also fluctuating therefore, the formation of robust system is of utmost importance for concomitant sustainable wastewater treatment and bioenergy production. In the present study, the tolerance and adaptability potential of algal consortia-1 (Chlorococcum humicola and Tetradesmus sp.) and consortia-2 (Chlorococcum humicola, Scenedesmus vacuolatus and Tetradesmus sp.) treated with municipal wastewater were examined under natural environmental conditions. The results exhibited that consortia-2 was more competent in recovering nitrate-nitrogen (82.92%), phosphorus (70.47%), and heavy metals (31-73.70%) from municipal wastewater (100%) than consortia-1. The results further depicted that total chlorophyll, carbohydrate, and protein content decreased significantly in wastewater-treated consortia-1 as compared to consortia-2. However, lipid content was increased by 4.01 and 1.17 folds in algal consortia-1 and consortia-2 compared to their respective controls. Moreover, absorption peak at 1740.6 cm -1  reflected higher biofuel-producing potential of consortia-1 as compared to consortia-2 as confirmed through FTIR spectroscopy. The results also revealed that consortia-2 showed the highest photosynthetic performance which was evident from the increment in the active photosystem-II reaction center (1.724 ± 0.068), quantum efficiency (0.633 ± 0.038), and performance index (3.752 ± 0.356). Further, a significant increase in photosynthetic parameters was observed in selected consortia at lag phase, while a noteworthy decline was observed at exponential and stationary phases in consortia-1 than consortia-2. The results also showed the maximum enhancement in ascorbic acid (2.43 folds), proline (3.34 folds), and cysteine (1.29 folds) in consortia-2, while SOD (1.75 folds), catalase (2.64 folds), and GR (1.19 folds) activity in consortia-1. Therefore, it can be concluded that due to remarkable flexibility and photosynthetic performance, consortia-2 could serve as a potential candidate for sustainable nutrient resource recovery and wastewater treatment, while consortia-1 for bio-fuel production in a natural environment. Thus, formation of algal consortia as the robust biosystem tolerates diverse environmental fluctuations together with wastewater complexity and ultimately can serve appropriate approach for environmental-friendly wastewater treatment and bioenergy production., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Photosynthetic diazotrophs expressing iron-only (Fe-only) nitrogenase can be developed into a promising biofertilizer, as it is independent on the molybdenum availability in the soil. However, the expression of Fe-only nitrogenase in diazotrophs is repressed by the fixed nitrogen of the soil, limiting the efficiency of nitrogen fixation in farmland with low ammonium concentrations that are inadequate for sustainable crop growth. Here, we succeeded in constitutively expressing the Fe-only nitrogenase even in the presence of ammonium by controlling the transcription of Fe-only nitrogenase gene cluster (anfHDGK) with the transcriptional activator of Mo nitrogenase (NifA*) in several different ways, indicating that the engineered NifA* strains can be used as promising chassis cells for efficient expression of different types of nitrogenases. When applied as a biofertilizer, the engineered Rhodopseudomonas palustris effectively stimulated rice growth, contributing to the reduced use of chemical fertilizer and the development of sustainable agriculture., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Feeding low-quality forage (LQF) has been evaluated in mature ruminants and results show that it has been improved nitrogen utilization efficiency. The present study evaluated the interaction effect of feeding wheat straw as LQF (0 and 7.5%, DM basis) and starter protein level (20 vs. 24%, DM basis) on growth performance, ruminal fermentation, and microbial protein synthesis in Holstein dairy calves raised under moderate heat stress condition. Forty-eight 3-day old dairy calves (averaging 40.6 kg) were assigned in four experimental treatments as follow; 1) no LQF with 20% CP (NLQF-20CP), 2) no LQF with 24% CP (NLQF-24CP), 3) 7.5% LQF with 20% CP (LQF-20CP) and 4) 7.5% LQF and 24% CP (LQF-24CP). The calves were weaned on d 53 of age but the experiment extended until d 73 of age. Feeding LQF increased starter intake, average daily gain (tendency), ruminal acetate concentration, and improved fecal score of calves. The average daily gains before and after weaning were positively influenced with greater starter protein content. Hence, weaning and final BWs were improved when calves received greater CP content. In addition, greater starter CP content increased total ruminal volatile fatty acid concentration. With respect to the interaction effect between LQF feeding and starter protein content, the lower nitrogen excretion through urine was obtained for LQF-20CP diet among experimental treatments. The results of the current study showed that feeding LQF improved ruminal fermentation pattern and improved growth performance through increased starter intake. In addition, greater starter protein content is advisable during pre-weaning period for calves raised under mild heat stress condition. In conclusion, based on the results found in the current study, it can be suggested that feeding LQF for calves under heat stress condition can improve nitrogen utilization when dietary protein content is low. This can be opportunity to formulate starter diets with greater nitrogen utilization efficiency which is critical for accelerated growth programs at early stages of growth for young calves while calves raised under hot season condition., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Herbicides are known to affect the soil nitrogen cycle by shaping soil microorganisms. However, it is not clear how herbicides regulate diverse transformation processes of soil nitrogen cycling by altering rhizosphere microorganisms, subsequently influencing the feedback to plant nitrogen metabolism. Here, we investigated how imazethapyr (IM) enantiomers drive plant-soil feedback on nitrogen metabolism by altering the rhizosphere microorganisms. The results indicated that (R)- and (S)-IM significantly changed the composition and structure rhizosphere microbiome with enantioselectivity and functional changes in microbial communities were associated with soil nitrogen circulation. The determination of nitrogen-cycling functional genes further supported the above findings. The results revealed that (R)- and (S)-IM could change the abundance of nitrogen-cycling functional genes by changing specific bacteria abundances, such as Bacteroidetes, Proteobacteria, and Acidobacteria, thus resulting in diverse nitrogen transformation processes. The alternation of nitrogen transformation processes indicated (R)-IM exhibited a more notable tendency to form a nitrogen cycling pattern with lower energy cost and higher nitrogen retention than (S)-IM. Sterilization experiments demonstrated changes in soil nitrogen cycling drive plant nitrogen metabolism and rhizosphere microorganisms are responsible for the above process of plant-soil feedback for nitrogen metabolism. Under IM enantiomer treatments, rhizosphere microorganisms might stimulate glutamate synthesis by promoting NH 4 uptake and glutamine-glutamate synthesis cycling in roots, thus contributing to positive feedback, with (R)-IM treatments showing more pronounced positive feedback on nitrogen metabolism than (S)-IM treatments. Our results provide theoretical support for determining the mechanism by which IM enantiomers drive plant-soil nitrogen metabolism by changing the rhizosphere microbial communities.+ uptake and glutamine-glutamate synthesis cycling in roots, thus contributing to positive feedback, with (R)-IM treatments showing more pronounced positive feedback on nitrogen metabolism than (S)-IM treatments. Our results provide theoretical support for determining the mechanism by which IM enantiomers drive plant-soil nitrogen metabolism by changing the rhizosphere microbial communities., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Aha Lake artificial reservoir wetland, Niangniang Mountain karst mountain wetland, and Caohai plateau lake wetland are typical karst wetlands in Guizhou Province with unique topography and geomorphic features. They were selected as research objects in this study to explore microorganisms and functional genes in nitrogen metabolism adopting macro-genome sequencing technology. It was found that Proteobacteria, Actinobacteria, and Acidobacteria were the dominant phyla in nitrogen metabolism in these three wetlands, similar to previous studies. However, at the genus level, there was a significant difference, with the dominant bacteria being Bradyrhizobium, Methylocystis, and Anaeromyxobacter. Six nitrogen metabolism pathways, including nitrogen fixation, nitrification, denitrification, dissimilatory nitrate reduction, assimilatory nitrate reduction, and complete nitrification, comammox, were revealed, but anaerobic ammonia oxidation genes were not detected. Nitrogen metabolism microorganisms and pathways were more affected by SOM, pH, NO 3 , and EC in karst wetlands. This study further discussed microorganisms and functions of nitrogen metabolism in karst wetlands, which was of great significance to nitrogen cycles of karst wetland ecosystems.- , and EC in karst wetlands. This study further discussed microorganisms and functions of nitrogen metabolism in karst wetlands, which was of great significance to nitrogen cycles of karst wetland ecosystems., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Anaerobic ammonium oxidation (anammox) sludge is easily deactivated in the process of treating ammonia-laden wastewater. To investigate an effective recovery method, red mud-based biochar carriers (RMBC) were prepared and added to a deactivated anammox reactor; the operation of this reactor had been interrupted for 6 months with starvation and low temperature. The deactivated sludge with added RMBC was recovered rapidly after 31 days, with the specific anammox activity rapidly increasing to 0.84 g N/(g VSS∙day), and the recovery efficiency of nitrogen removal rate increased by four times compared to the unadded control. The granulation degree and extracellular polymeric substances secretion of the anammox sludge with the added RMBC were significantly higher than that of the control group. In addition, a large number of spherical anammox bacteria were observed moored at the porous channels of RMBC, and the copy numbers of functional genes of anammox bacteria were approximately twice that of the control group. Hence, RMBC is a potential sludge activator, and it can provide a "house" to protect anammox bacteria, enhance the metabolic activity and the agglomerative growth of anammox bacteria, and synergistically achieve rapid recovery of deactivated anammox sludge., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Flavonoids have been recognized as potential phytochemicals to reduce enteric methane (CH 4 ) production and improve rumen nitrogen efficiency in ruminants. We evaluated whether naringin, hesperidin, their combination, or a mixed citrus flavonoid extract (CFE) as additives can inhibit methanogenesis and ammoniagenesis in dairy cows using an in vitro rumen batch refermentation system. The rumen inocula from dairy cows were incubated in batch cultures with five groups: no addition (CON), hesperidin (20 g/kg DM), naringin (20 g/kg DM), hesperidin + naringin (10 g/kg DM of hesperidin + 10 g/kg DM of naringin), and CFE (20 g/kg DM). The combination of naringin plus hesperidin and CFE achieved greater reductions in CH 4 and ammonia production compared to either naringin or hesperidin alone. Microbiome analysis revealed that the decrease in CH 4 emissions may have been caused by both the direct inhibitory impact of citrus flavonoids on Methanobrevibacter and a simultaneous decrease in protozoa Isotricha abundance. The relatively lower proportion of Entodinium in naringin plus hesperidin or CFE was responsible for the lower ammonia concentration. These results suggest that citrus flavonoids possess potential synergistic effects on mitigating ruminal CH 4 emissions by cows and improving nitrogen utilization., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Nitrate (NO 3 - ) is the primary source of nitrogen preferred by most arable crops, including wheat. The pioneering experiment on primary nitrate response (PNR) was carried out three decades ago. Since then, much research has been carried out to understand the NO 3 - signaling. Nitrate is sensed by the dual affinity NO 3 - transceptor NPF6.3, which further relays the information to a master regulator NIN-like protein 7 (NLP7) through calcium-dependent protein kinases (CPK10, CPK30, CPK32), highlighting the importance of calcium ion (Ca 2+ ) as one of the important secondary messengers in relaying the NO 3 - signaling in Arabidopsis. In a previous study, we found that Ca 2+ regulates nitrogen starvation response in wheat. In this study, 10 days old NO 3 - -starved wheat seedlings were exposed to various treatments. Our study on time course changes in expression of PNR sentinel genes; NPF6.1, NPF6.2, NRT2.1, NRT2.3, NR, and NIR in wheat manifest the highest level of expression at 30 min after NO 3 - exposure. The use of Ca 2+ chelator EGTA confirmed the involvement of Ca 2+ in the regulation of transcription of NPFs and NRTs as well the NO 3 - uptake. We also observed the NO 3 - dose-dependent and tissue-specific regulation of nitrate reductase activity involving Ca 2+ as a mediator. The participation of Ca 2+ in the PNR and NO 3 - signaling in wheat is confirmed by pharmacological analysis, physiological evidences, and protoplast-based Ca 2+ localization., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Key Message: Different wheat QTLs were associated to the free asparagine content of grain grown in four different conditions. Environmental effects are a key factor when selecting for low acrylamide-forming potential. The amount of free asparagine in grain of a wheat genotype determines its potential to form harmful acrylamide in derivative food products. Here, we explored the variation in the free asparagine, aspartate, glutamine and glutamate contents of 485 accessions reflecting wheat worldwide diversity to define the genetic architecture governing the accumulation of these amino acids in grain. Accessions were grown under high and low nitrogen availability and in water-deficient and well-watered conditions, and plant and grain phenotypes were measured. Free amino acid contents of grain varied from 0.01 to 1.02 mg g -1 among genotypes in a highly heritable way that did not correlate strongly with grain yield, protein content, specific weight, thousand-kernel weight or heading date. Mean free asparagine content was 4% higher under high nitrogen and 3% higher in water-deficient conditions. After genotyping the accessions, single-locus and multi-locus genome-wide association study models were used to identify several QTLs for free asparagine content located on nine chromosomes. Each QTL was associated with a single amino acid and growing environment, and none of the QTLs colocalised with genes known to be involved in the corresponding amino acid metabolism. This suggests that free asparagine content is controlled by several loci with minor effects interacting with the environment. We conclude that breeding for reduced asparagine content is feasible, but should be firmly based on multi-environment field trials., Key Message: Different wheat QTLs were associated to the free asparagine content of grain grown in four different conditions. Environmental effects are a key factor when selecting for low acrylamide-forming potential., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The effectiveness of Methylobacterium symbioticum in maize and strawberry plants was measured under different doses of nitrogen fertilisation. The biostimulant effect of the bacteria was observed in maize and strawberry plants treated with the biological inoculant under different doses of nitrogen fertiliser compared to untreated plants (control). It was found that bacteria allowed a 50 and 25% decrease in the amount of nitrogen applied in maize and strawberry crops, respectively, and the photosynthetic capacity increased compared with the control plant under all nutritional conditions. A decrease in nitrate reductase activity in inoculated maize plants indicated that the bacteria affects the metabolism of the plant. In addition, inoculated strawberry plants grown with a 25% reduction in nitrogen had a higher concentration of nitrogen in leaves than control plants under optimal nutritional conditions. Again, this indicates that Methylobacterium symbioticum provide an additional supply of nitrogen., (© 2023. The Author(s).)

Due to the rapid development of animal husbandry, the associated environmental problems cannot be ignored, with the management of livestock and poultry manure emerging as the most prominent issue. Composting technology has been widely used in livestock and poultry manure management. A deeper understanding of the nitrogen conversion process during composting offers a theoretical foundation for selecting compost substrates. In this study, the effects of sawdust (CK) and spent mushroom compost (T1) as auxiliary materials on nitrogen as well as microbial structure in the composting process when composted with chicken manure were investigated. At the end of composting, the nitrogen loss of T1 was reduced by 17.18% relative to CK. When used as a compost substrate, spent mushroom compost accelerates the succession of microbial communities within the compost pile and alters the core microbial communities within the microbial community. Bacterial genera capable of cellulose degradation (Fibrobacter, Herbinix) are new core microorganisms that influence the assimilation of nitrate reduction during compost maturation. Using spent mushroom compost as a composting substrate increased the enzyme activity of nitrogen assimilation while decreasing the enzyme activity of the denitrification pathway., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The family Phyllobacteriaceae is a heterogeneous assemblage of more than 146 species of bacteria assigned to its existing 18 genera. Phylogenetic analyses have shown great phylogenetic diversity and also suggested about incorrect classification of several species that need to be reassessed for their proper phylogenetic classification. However, almost 50% of the family members belong to the genus Mesorhizobium only, of which the majority are symbiotic nitrogen fixers associated with different legumes. Other major genera are Phyllobacterium, Nitratireductor, Aquamicrobium, and Aminobacter. Nitrogen-fixing, legume nodulating members are present in Aminobacter and Phyllobacterium as well. Aquamicrobium spp. can degrade environmental pollutants, like 2,4-dichlorophenol, 4-chloro-2-methylphenol, and 4-chlorophenol. Chelativorans, Pseudaminobacter, Aquibium, and Oricola are the other genera that contain multiple species having diverse metabolic capacities, the rest being single-membered genera isolated from varied environments. In addition, heavy metal and antibiotic resistance, chemolithoautotrophy, poly-β-hydroxybutyrate storage, cellulase production, etc., are the other notable characteristics of some of the family members. In this report, we have comprehensively reviewed each of the species of the family Phyllobacteriaceae in their eco-physiological aspects and found that the family is rich with ecologically and metabolically highly diverse bacteria having great potential for human welfare and environmental clean-up., (© 2023. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

A survey for bacteria of the genus Thiothrix indicated that they inhabited the area where the water of the Zmeiny geothermal spring (northern basin of Lake Baikal, Russia) mixed with the lake water. In the coastal zone of the lake oxygen (8.25 g/L) and hydrogen sulfide (up to 1 mg/L) were simultaneously present at sites of massive growth of these particular Thiothrix bacteria. Based on the analysis of the morphological characteristics and sequence of individual genes (16S rRNA, rpoB and tilS), we could not attribute the Thiothrix from Lake Baikal to any of the known species of this genus. To determine metabolic capabilities and phylogenetic position of the Thiothrix sp. from Lake Baikal, we analyzed their whole genome. Like all members of this genus, the bacteria from Lake Baikal were capable of organo-heterotrophic, chemolithoheterotrophic, and chemolithoautotrophic growth and differed from its closest relatives in the spectrum of nitrogen and sulfur cycle genes as well as in the indices of average nucleotide identity (ANI < 75-94%), amino acid identity (AAI < 94%) and in silico DNA-DNA hybridization (dDDH < 17-57%), which were below the boundary of interspecies differences, allowing us to identify them as novel candidate species., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The objective of this research was to evaluate how pregnancy and feeding regimens affect the feed intake, digestibility, and efficiency of microbial nitrogen (N) synthesis in beef cows. Forty-four multiparous Nellore cows, comprising 32 gestating and 12 non-gestating cows, with an average weight of 451 ± 10 kg, were assigned to either a HIGH (ad libitum) or LOW (limited feeding at 1.2 times maintenance based on the NRC) feeding regimen during the gestational period. The dry matter intake (DMI) in kg/d was significantly greater (P < 0.01) in HIGH-fed cows. The DMI reduced (P < 0.05) in proportion to the shrunk body weight (SBW) as days of pregnancy (DOP) increased. The interaction between feeding level and DOP was significant (P < 0.05) for the digestibility of dry matter (DM), organic matter (OM), N compounds, ether extract (EE), ash- and protein-free neutral detergent fiber (NDFap), gross energy (GE), and total digestible nutrients (TDN). Except for DM and TDN digestibility, there was a reduced nutrient digestibility as gestation progressed in HIGH-fed cows. In contrast, digestibility increased as a function of DOP in LOW-fed cows. Microbial N synthesis (g/day) was significantly higher in HIGH-fed cows (P < 0.001) compared to LOW-fed cows. The efficiency of microbial N production per g of N intake and kg of digestible OM intake was (P = 0.021) and tended (P = 0.051) to be greater in LOW-fed cows compared to HIGH-fed cows. In summary, HIGH-fed Nellore cows reduce feed intake and digestibility with advancing gestation, affecting feed utilization. In addition, LOW-fed cows, showed higher microbial protein synthesis efficiency, potentially making them more nutrient-efficient under challenging nutritional conditions., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Key Message: The weighted gene co-expression network analysis and antisense oligonucleotide-mediated transient gene silencing revealed that CsAAP6 plays an important role in amino acid transport during tea shoot development. Nitrogen transport from source to sink is crucial for tea shoot growth and quality formation. Amino acid represents the major transport form of reduced nitrogen in the phloem between source and sink, but the molecular mechanism of amino acid transport from source leaves to new shoots is not yet clear. Therefore, the composition of metabolites in phloem exudates collected by the EDTA-facilitated method was analyzed through widely targeted metabolomics. A total of 326 metabolites were identified in the phloem exudates with the richest variety of amino acids and their derivatives (93), accounting for approximately 39.13% of the total metabolites. Moreover, through targeted metabolomics, it was found that the content of glutamine, glutamic acid, and theanine was the most abundant, and gradually increased with the development of new shoots. Meanwhile, transcriptome analysis suggested that the expression of amino acid transport genes changed significantly. The WGCNA analysis identified that the expression levels of CsAVT1, CsLHTL8, and CsAAP6 genes located in the MEterquoise module were positively correlated with the content of amino acids such as glutamine, glutamic acid, and theanine in phloem exudates. Reducing the CsAAP6 in mature leaves resulted in a significant decrease in the content of glutamic acid, aspartic acid, alanine, leucine, asparagine, glutamine, and arginine in the phloem exudates, indicating that CsAAP6 played an important role in the source to sink transport of amino acids in the phloem. The research results will provide the theoretical basis and genetic resources for the improvement of nitrogen use efficiency and tea quality., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Following the principle of oxygenic photosynthesis, electron transport in the thylakoid membranes (i.e., light reaction) generates ATP and NADPH from light energy, which is subsequently utilized for CO 2 fixation in the Calvin-Benson-Bassham cycle (i.e., dark reaction). However, light and dark reactions could discord when an alternative electron flow occurs with a rate comparable to the linear electron flow. Here, we quantitatively monitored O 2 and total dissolved inorganic carbon (DIC) during photosynthesis in the pennate diatom Phaeodactylum tricornutum, and found that evolved O 2 was larger than the consumption of DIC, which was consistent with 14 CO 2 measurements in literature. In our measurements, the stoichiometry of O 2 evolution to DIC consumption was always around 1.5 during photosynthesis at different DIC concentrations. The same stoichiometry was observed in the cells grown under different CO 2 concentrations and nitrogen sources except for the nitrogen-starved cells showing O 2 evolution 2.5 times larger than DIC consumption. An inhibitor to nitrogen assimilation did not affect the extra O 2 evolution. Further, the same physiological phenomenon was observed in the centric diatom Thalassiosira pseudonana. Based on the present dataset, we propose that the marine diatoms possess the metabolic pathway(s) functioning as the O 2 -independent electron sink under steady state photosynthesis that reaches nearly half of electron flux of the Calvin-Benson-Bassham cycle., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Biological soil crusts (BSCs) are common in arid and semi-arid ecosystems and enhance soil stability and fertility. Highway slopes severely deplete the soil ecological structure and soil nutrients, hindering plant survival. The construction of highway slope BSCs under human intervention is critical to ensure the long-term stable operation of the slope ecosystem. This study investigated the variation rules and interaction mechanisms between soil nutrients and microbial communities in the subsoil BSCs on highway slopes. Bacterial 16S rRNA high-throughput sequencing was employed to investigate the dynamic compositional changes in the microbial community and perform critical metabolic predictive analyses of functional bacteria. This study revealed that the total soil nitrogen increased significantly from 0.557 to 0.864 g/kg after artificial inoculation with desert Phormidium tenue and Scytonema javanicum. Actinobacteria (44-48%) and Proteobacteria (28-31%) were the dominant phyla in all samples. The abundance of Cyanobacteria, Cytophagaceae, and Chitinophagaceae increased significantly after inoculation. PICRUST analysis showed that the main metabolic pathways of soil microorganisms on highway slopes included cofactor and vitamin, nucleotide, and amino acid metabolisms. These findings suggest that the artificial inoculation with Phormidium tenue and Scytonema javanicum could alter soil microbial distribution to promote soil development on highway slopes toward nutrient accumulation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Globally, the price of soybean meal, the most common proteinaceous ingredient in livestock diets, has become highly expensive prompting a search for alternative ingredients. Hemp seed cake is a promising alternative but could be limited by its high neutral detergent fiber and ether extract contents which impede nutrient intake and digestibility. However, some ruminant species such as goats have superior ability to digest high fiber and ether extract diets. Thus, the current research evaluated nutrient intake and digestibility, rumen fermentation, and microbial protein synthesis of goats fed hempseed cake as a substitute for soybean meal in finisher diets. A total of 25 Kalahari Red castrates (27 ± 3 kg, 4-5 months old) were assigned to five dietary treatments (5 goats/ diet) in a completely randomized design. A maize-lucerne-based finishing diet was formulated with hempseed cake substituting soybean meal as the primary protein ingredient at 0, 25, 50, 75, or 100 g/kg dry matter. Ether extract intake exhibited a positive linear trend (P ≤ 0.05) while crude protein intake and microbial nitrogen supply exhibited a negative linear trend (P ≤ 0.05) with dietary inclusion of hempseed cake. However, feeding hempseed cake did not influence (P > 0.05) apparent nutrient digestibility, rumen fermentation parameters and nitrogen use efficiency. In conclusion, the substitution of soybean meal for hempseed cake decreased crude protein intake and microbial nitrogen supply in goat finisher diets without compromising nutrient digestibility and nitrogen use efficiency. The study recommends partial or full replacement of soybean meal with hempseed cake in goat finisher diets., (© 2023. The Author(s).)