Search

Rainforests provide vital ecosystem services that are underpinned by plant-soil interactions. The forests of Borneo are globally important reservoirs of biodiversity and carbon, but a significant proportion of the forest that remains after large-scale agricultural conversion has been extensively modified due to timber harvest. We have limited understanding of how selective logging affects ecosystem functions including biogeochemical cycles driven by soil microbes. In this study, we sampled soil from logging gaps and co-located intact lowland dipterocarp rainforest in Borneo. We characterised soil bacterial and fungal communities and physicochemical properties and determined soil functioning in terms of enzyme activity, nutrient supply rates, and microbial heterotrophic respiration. Soil microbial biomass, alpha diversity, and most soil properties and functions were resistant to logging. However, we found logging significantly shifted soil bacterial and fungal community composition, reduced the abundance of ectomycorrhizal fungi, increased the abundance of arbuscular mycorrhizal fungi, and reduced soil inorganic phosphorous concentration and nitrate supply rate, suggesting some downregulation of nutrient cycling. Within gaps, canopy openness was negatively related to ectomycorrhizal abundance and phosphomonoesterase activity and positively related to ammonium supply rate, suggesting control on soil phosphorus and nitrogen cycles via functional shifts in fungal communities. We found some evidence for reduced soil heterotrophic respiration with greater logging disturbance. Overall, our results demonstrate that while many soil microbial community attributes, soil properties, and functions may be resistant to selective logging, logging can significantly impact the composition and abundance of key soil microbial groups linked to the regulation of vital nutrient and carbon cycles in tropical forests. [ABSTRACT FROM AUTHOR]

Summary Cover crop integration into grain crop rotations is a promising strategy for mitigating nematode‐induced diseases in agriculture. However, the precise mechanisms underlying this phenomenon remain elusive. Here, we first assessed the impact of five commonly used cover crops on the suppression of rice root‐knot nematodes (RKNs). We then chose ryegrass as a model to explore the mechanistic basis of the suppression effect. Contrary to expectations, while ryegrass rotation significantly enhances soil fertility, this increased fertility has minimal impact on RKN suppression. Furthermore, neither integrated ryegrass residues nor root exudates exhibit direct toxicity towards RKNs. We demonstrated that ryegrass rotation primarily suppresses RKNs by enriching beneficial soil microbiota. By complementing with isolated bacteria strains, we further demonstrated that ryegrass‐enriched bacteria not only directly reduce RKN infectivity and preference, but also activate plant immunity via the OsLRR‐RLK‐MAPK‐WRKY‐JA cascade, thereby diminishing RKN infection. Our study highlights the crucial role of soil microbiota in plant–nematode interactions, challenging conventional views on the direct effects of cover crops in nematode suppression. It offers a mechanistic understanding of the regulation potential and action modes of cover crops in mitigating nematode diseases, providing valuable insights for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Objectives: This research aimed to identify and quantify the antibiofilm activity of bioactive compounds from bacteria isolated from rhizosphere and nodule butterfly pea (Clitoria ternatea), rhizosphere clove afo 3 (Syzygium aromaticum), nodule mimosa (Mimosa pudica L.), and soil from gold mining land which were recovered from Ternate, Tidore, Obi Island, and Marotai Island, Eastern part of Indonesia. Results: Eight supernatants from soil and plant-associated bacteria were found to have quorum quenching activity against Chromobacterium violaceum. All supernatants exhibited antibiofilm activity against biofilm formed by Aeromonas hydrophila and Vibrio harveyi. The supernatant of FT5 showed the highest activity in disrupting (66.59%) and inhibiting (85.63%) the biofilm of A. hydrophila. For V. harveyi, the supernatant of PTM3 showed the highest disruption activity (72.61%), whileRCA7 showed the highest inhibition activity(75.68%). The Gas Chromatography-Mass Spectrometry (GC-MS) identified fatty acids, ester, and diketopiperazine as the compounds related to the antibiofilm activity. Molecular identification revealed that the isolates belong to the genera Bacillus, Priestia, and Chryseobacterium. [ABSTRACT FROM AUTHOR]

The persistent and hazardous nature of polycyclic aromatic hydrocarbons (PAHs) released into the soil has become a critical global concern, contributing to environmental pollution. In this study, the removal efficiency of phenanthrene and naphthalene degradation by complex flora or pure bacteria combined with corn and their effects on the growth of corn, pH, and the number of soil bacteria were investigated using a pot experiment. The results indicate that the corn remediation method (P) outperformed degrading bacteria remediation (B) for phenanthrene, yet the combination (PB) exhibited significantly higher removal efficiency. The degradation efficiency of PB methods increased over time, ranging from 58.40% to 75.13% after 30 days. Naphthalene removal showed a similar trend. Soil pH, influenced by remediation methods, experienced slight but non-significant increases. The number of degrading bacteria increased with combined methods, notably with PB-W1 and PB-W2 treatments. Corn accumulated phenanthrene and naphthalene, with higher concentrations in roots. Remediation by the combined corn and degrading bacteria slightly increased PAH accumulation, indicating potential root protection. Biomass yield analysis revealed the inhibitory effects of PAHs on corn growth, decreased by degrading bacteria. PB-W1 and PB-EF3 demonstrated the highest fresh weight and moisture content for stem and leaf biomass, while PB-F2-6 excelled in root biomass. Overall, combined remediation methods proved more effective, which underscores the potential of the corn and degrading bacteria consortium for efficient PAH remediation in contaminated soil. [ABSTRACT FROM AUTHOR]

Mountain regions play a crucial role in maintaining global biodiversity, with altitude exerting a significant influence on soil microbial diversity by altering plant diversity, soil nutrients, and microclimate. However, differences in microbial community composition between topsoil (0–10 cm deep) and subsoil (10–20 cm deep) remain poorly understood. Here, we aimed to assess soil microbial diversity, microbial network complexity, and microbial community assembly in the topsoil and subsoil layers of the dry–hot Jinsha River valley in southwestern China. Using high-throughput sequencing in soil samples collected along an altitudinal gradient, we found that bacterial diversity in topsoil decreased with increasing altitude, while bacterial diversity in subsoil showed no altitude-dependent changes. Fungal diversity in topsoil also varied with altitude, while subsoil fungal diversity showed no change. These findings suggest that microbial diversity in topsoil was more sensitive to changes in altitude than subsoil. Bacterial community assembly tended to be governed by stochastic processes, while fungal assembly was deterministic. Soil bacterial and fungal network complexity was enhanced with increasing altitude but reduced as diversity increased. Interestingly, the presence of woody plant species negatively affected bacterial and fungal community composition in both soil layers. Soil pH and water content also negatively affected microbial community composition, while organic carbon and total nitrogen positively influenced the microbial community composition. Simultaneously, herb and woody plant diversity mainly affected soil bacterial diversity in the topsoil and subsoil, respectively, while woody plant diversity mainly affected soil fungal diversity in subsoil and soil nutrients had more effect on soil fungal diversity. These findings suggest that altitude directly and indirectly affects microbial diversity in topsoil, subsequently influencing microbial diversity in subsoil through nutrient availability. [ABSTRACT FROM AUTHOR]

The improvement of saline-alkali land plays a key role in ensuring food security and promoting agricultural development. Saline soils modifies the response of the soil microbial community, but research is still limited. The effects of applying phosphogypsum with rice cultivation (PRC) on soil physicochemical properties and bacterial community in soda saline-alkali paddy fields in Songnen Plain, China were studied. The results showed that the PRC significantly improved the physicochemical properties of soil, significantly reduced the salinity, increased the utilization efficiency of carbon, nitrogen, and phosphorus, and significantly increased the activities of urease and phosphatase. The activities of urease and phosphatase were significantly correlated with the contents of total organic carbon and total carbon. A redundancy analysis showed that pH, AP, ESP, HCO3−, and Na+ were dominant factors in determining the bacterial community structure. The results showed that PRC could improve soil quality and enhance the ecosystem functionality of soda saline-alkali paddy fields by increasing nutrient content, stimulating soil enzyme activity, and regulating bacterial community improvement. After many years of PRC, the soda-alkali soil paddy field still develops continuously and healthily, which will provide a new idea for sustainable land use management and agricultural development. [ABSTRACT FROM AUTHOR]

Soil salinization seriously affects soilmicrobial diversity, and crop yield and quality worldwide. Microorganisms play a vital role in the process of crop yield and quality. Traditional Chinese medicine Glycyrrhiza uralensis Fisch. (licorice) can grow tenaciously in the heavily salinized land. However, the relationship between licorice plants and soilmicroorganisms is not clear. A field experiment was carried out to explore the effects of three different degrees of salinized soils on (i) licorice crop performance indicators, (ii) soil physical and chemical properties, and (iii) the changes in soil bacterial community structure and functional diversity in a semi-arid area of northwest China. The results showed that with the aggravation of soil salinization, the licorice yield, soil nutrients, and the bacterial abundance of Gemmatimonadetes and Myxococcota showed a downward trend, while the concentration of glycyrrhizic acid and liquiritin, and the bacterial abundance of Actinobacteria and Firmicutes showed an upward trend. The change of licorice yield mainly depended on the soil physical and chemical properties (e.g., EC and alkaline hydrolysable nitrogen). The change of licorice quality was more closely related to the change of bacterial diversity. The effect of bacterial diversity on liquiritin was greater than that on glycyrrhizic acid. Among them, Gemmatimonadetes were significantly negatively correlated with liquiritin and glycyrrhizic acid. These findings suggest that the increased soil Actinobacteria and Firmicutes or reduced Gemmatimonadetes and Myxococcota may provide a healthy and suitable living condition for the sustainable development of medicinal plant crops in a salinized soil ecosystem. [ABSTRACT FROM AUTHOR]

Background: The expansion of bamboo forests increases environmental heterogeneity in tea plantation ecosystems, affecting soil properties and microbial communities. Understanding these impacts is essential for developing sustainable bamboo management and maintaining ecological balance in tea plantations. Methods: We studied the effect of the continuous expansion of Pleioblastus amarus into tea plantations, by establishing five plot types: pure P. amarus forest area (BF), P. amarus forest interface area (BA), mixed forest interface area (MA), mixed forest center area (TB), and pure tea plantation area (TF). We conducted a comprehensive analysis of soil chemical properties and utilized Illumina sequencing to profile microbial community composition and diversity, emphasizing their responses to bamboo expansion. Results: (1) Bamboo expansion significantly raised soil pH and enhanced levels of organic matter, nitrogen, and phosphorus, particularly noticeable in BA and MA sites. In the TB sites, improvements in soil nutrients were statistically indistinguishable from those in pure tea plantation areas. (2) Continuous bamboo expansion led to significant changes in soil bacterial diversity, especially noticeable between BA and TF sites, while fungal diversity was unaffected. (3) Bamboo expansion substantially altered the composition of less abundant bacterial and fungal communities, which proved more sensitive to changes in soil chemical properties. Conclusion: The expansion of bamboo forests causes significant alterations in soil pH and nutrient characteristics, impacting the diversity and composition of soil bacteria in tea plantations. However, as expansion progresses, its long-term beneficial impact on soil quality in tea plantations appears limited. [ABSTRACT FROM AUTHOR]

Composting is an environmentally friendly process, turning animal waste into fertilizer. Chicken litter compost (CLC) improves soil properties, increasing crop yields. However, the CLC effect on the soil microbiome is understudied. This study aimed to compare bacteriobiome diversity in fallow arable Chernozem with and without CLC addition in a field experiment in the Novosibirsk region, Russia, using 16S rRNA gene metabarcoding. Pseudomonadota, Actinomycetota and Acidobacteriota were the most OTU-rich phyla, together accounting for >50% of the total number of sequence reads. CLC-related shifts in the bacteriobiome structure occurred at all taxonomic levels: the Bacillota abundance was 10-fold increased due to increased Bacilli, both being indicator taxa for the CLC-soil. The main Actinomycetota classes were the indicators for the CLC-soil (Actinobacteria) and no-CLC soil (Thermoleophilia, represented Gaiella). Both Bacillota and Actinomycetota phyla were the ultimate constituents of the CLC added, persisting in the soil for five months of fallowing. The no-CLC soil indicator phyla were Acidobacteriota (represented by Acidobacteria_Group3) and Verrucomicrobiota. Future metabarcoding studies of chicken litter application in agricultural soils, including cropped studies, should address the soil microbiome at the species/strain levels in more detail, as well as how it is affected by specific crops, preferably accompanied by a direct methodology revealing the microbiota functions. [ABSTRACT FROM AUTHOR]

Wildfires have become increasingly common across the United States in recent decades, with significant implications for ecosystem health and sustainability. The viability and metabolic activity of soil bacteria are key for maintaining global nitrogen-cycling processes and are likely to be impacted as burn severity continues to increase. To this end, wildfire-affected soils were studied to examine the impact on nitrogen-cycling bacteria in soils affected by low, moderate, and high wildfire severities. This objective was achieved by characterizing soil bacterial communities in control (i.e., unburned) and burned soils collected one year following the Woolsey wildfire (Los Angeles and Ventura Counties, CA, USA) using Illumina MiSeq 16S sequencing and profiling nitrogen-cycling gene expression using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Six families and 17 genera were significantly (Spearman rs > |0.4|; p < 0.05) negatively associated with wildfire severity, and three families and six genera were significantly positively associated with wildfire severity. Many of these taxa contain species that are known to be critical contributors to maintaining global nitrogen cycles. NosZ and NirS nitrifying genes had significantly lower transcription rates in high-severity samples compared with control and low/moderate-severity samples. Collectively, these results suggest that high-severity wildfires significantly negatively alter the community structures and functions of nitrogen-cycling bacteria, which may have significant ramifications for ecosystem recovery in postwildfire landscapes. [ABSTRACT FROM AUTHOR]

Abstract Objectives This research aimed to identify and quantify the antibiofilm activity of bioactive compounds from bacteria isolated from rhizosphere and nodule butterfly pea (Clitoria ternatea), rhizosphere clove afo 3 (Syzygium aromaticum), nodule mimosa (Mimosa pudica L.), and soil from gold mining land which were recovered from Ternate, Tidore, Obi Island, and Marotai Island, Eastern part of Indonesia. Results Eight supernatants from soil and plant-associated bacteria were found to have quorum quenching activity against Chromobacterium violaceum. All supernatants exhibited antibiofilm activity against biofilm formed by Aeromonas hydrophila and Vibrio harveyi. The supernatant of FT5 showed the highest activity in disrupting (66.59%) and inhibiting (85.63%) the biofilm of A. hydrophila. For V. harveyi, the supernatant of PTM3 showed the highest disruption activity (72.61%), whileRCA7 showed the highest inhibition activity(75.68%). The Gas Chromatography-Mass Spectrometry (GC-MS) identified fatty acids, ester, and diketopiperazine as the compounds related to the antibiofilm activity. Molecular identification revealed that the isolates belong to the genera Bacillus, Priestia, and Chryseobacterium.

Due to the adverse ecological impacts of prolonged and excessive use of agrochemicals, many researchers have called for the adoption of eco-friendly materials in farming. Consequently, the aim of this study is to profile the biocontrol agents, nitrogen-fixing, and indole-acetic-acid-producing bacteria present in anthill soil. Anthill soils and adjacent soils were collected, and their physicochemical properties were analysed using standard analytical methods. Viable bacteria were isolated and screened for plant growth-promoting (PGP) activity using standard biochemical, morphological, and bacteriological methods. The PGP capacity of the isolates was evaluated using standard protocol for nitrogen fixation and indole-acetic-acid production, while antagonistic effect against plant pathogens was evaluated using the disk diffusion assay. Results revealed that Pseudomonas aeruginosa, Klebsiella pneumoniae, and Bacillus sp. isolated from the anthill soil demonstrated PGP characteristics including IAA production and nitrogen fixation. Bacillus sp. exhibited zones of clearance with values of 20.00 ± 1.50 mm, 20.00 ± 1.75 mm, 17.00 ± 1.33 mm, and 17.00 ± 1.33 mm against Aspergillus niger, Trichoderma sp., Penicillium sp., and Fusarium sp., respectively. This study demonstrated that anthill soils contain beneficial microbes with the potential to stimulate plant growth and suppress soil-borne plant pathogens

Composting is an environmentally friendly process, turning animal waste into fertilizer. Chicken litter compost (CLC) improves soil properties, increasing crop yields. However, the CLC effect on the soil microbiome is understudied. This study aimed to compare bacteriobiome diversity in fallow arable Chernozem with and without CLC addition in a field experiment in the Novosibirsk region, Russia, using 16S rRNA gene metabarcoding. Pseudomonadota, Actinomycetota and Acidobacteriota were the most OTU-rich phyla, together accounting for >50% of the total number of sequence reads. CLC-related shifts in the bacteriobiome structure occurred at all taxonomic levels: the Bacillota abundance was 10-fold increased due to increased Bacilli, both being indicator taxa for the CLC-soil. The main Actinomycetota classes were the indicators for the CLC-soil (Actinobacteria) and no-CLC soil (Thermoleophilia, represented Gaiella). Both Bacillota and Actinomycetota phyla were the ultimate constituents of the CLC added, persisting in the soil for five months of fallowing. The no-CLC soil indicator phyla were Acidobacteriota (represented by Acidobacteria_Group3) and Verrucomicrobiota. Future metabarcoding studies of chicken litter application in agricultural soils, including cropped studies, should address the soil microbiome at the species/strain levels in more detail, as well as how it is affected by specific crops, preferably accompanied by a direct methodology revealing the microbiota functions.

Abstract Background The expansion of bamboo forests increases environmental heterogeneity in tea plantation ecosystems, affecting soil properties and microbial communities. Understanding these impacts is essential for developing sustainable bamboo management and maintaining ecological balance in tea plantations. Methods We studied the effect of the continuous expansion of Pleioblastus amarus into tea plantations, by establishing five plot types: pure P. amarus forest area (BF), P. amarus forest interface area (BA), mixed forest interface area (MA), mixed forest center area (TB), and pure tea plantation area (TF). We conducted a comprehensive analysis of soil chemical properties and utilized Illumina sequencing to profile microbial community composition and diversity, emphasizing their responses to bamboo expansion. Results (1) Bamboo expansion significantly raised soil pH and enhanced levels of organic matter, nitrogen, and phosphorus, particularly noticeable in BA and MA sites. In the TB sites, improvements in soil nutrients were statistically indistinguishable from those in pure tea plantation areas. (2) Continuous bamboo expansion led to significant changes in soil bacterial diversity, especially noticeable between BA and TF sites, while fungal diversity was unaffected. (3) Bamboo expansion substantially altered the composition of less abundant bacterial and fungal communities, which proved more sensitive to changes in soil chemical properties. Conclusion The expansion of bamboo forests causes significant alterations in soil pH and nutrient characteristics, impacting the diversity and composition of soil bacteria in tea plantations. However, as expansion progresses, its long-term beneficial impact on soil quality in tea plantations appears limited.

Changes in land use strongly affect soil biological and physico-chemical structure and characteristics, which are strongly related to agricultural conversion of natural habitats to man-made usage. These are among the most important and not always beneficial changes, affecting loss of habitats. In Golan Heights basaltic soils, vineyards are currently a driving force in land-use change. Such changes could have an important effect on soil microbial community that play an important role in maintaining stable functioning of soil ecosystems. This study investigated the microbial communities in five different agro-managements using molecular tools that can clarify the differences in microbial community structure and function. Significant differences in soil microbial community composition were found. However, no differences in alpha diversity or functionality were found between the treatments. To the best of our knowledge, this is the first report indicating that the bacterial community in different agro-managements provide an insight into the potential function of a vineyard system. [ABSTRACT FROM AUTHOR]

Here, phytoremediation studies of toxic metal and organic compounds using plants augmented with plant growth-promoting bacteria, published in the past few years, were summarized and reviewed. These studies complemented and extended the many earlier studies in this area of research. The studies summarized here employed a wide range of non-agricultural plants including various grasses indigenous to regions of the world. The plant growth-promoting bacteria used a range of different known mechanisms to promote plant growth in the presence of metallic and/or organic toxicants and thereby improve the phytoremediation ability of most plants. Both rhizosphere and endophyte PGPB strains have been found to be effective within various phytoremediation schemes. Consortia consisting of several PGPB were often more effective than individual PGPB in assisting phytoremediation in the presence of metallic and/or organic environmental contaminants.

The lipid-producing gram-positive bacteria were isolated from soil and it was identified as Streptomyces fradiae JJ1 MK733985.1. Bacterial lipid synthesis was explored using rice washed water through the fermentation research. The exponential growth phase was reached on the fifth day of fermentation, according to the results. The ability of Streptomyces fradiae to produce microbial oil was compared to that of International Streptomyces Project-2 Medium (ISP2) medium. The results showed that RWW culture medium yielded 85.4% fatty acids and 60.3 g/L biomass, while ISP2 medium yielded 83.2% wt fatty acids and 59.5 g/L biomass. The microbial oil was transesterified into Fatty acid methyl esters (FAME), and its characteristics were studied using American Society for Testing Materials (ASTM) standards. The specific gravity was 0.864, the density was 0.863, the gross heating value was 42498 kj/kg, the cetane number was 37, and the acid value was 0.46. Streptomyces fradiae grew with an ISP2 density of 0.835, specific gravity of 0.845, gross heating value of 42326 kj/kg, and acid value of 0.43. According to the findings, Streptomyces fradiae isolated from soil can grow in RWW medium for the first time and provide the same yield as commercial media while being significantly less expensive.

Cadmium (Cd) is a harmful metal in soil, and reducing Cd accumulation in plants has become a vital prerequisite for maintaining food safety. Phosphate-solubilizing bacteria (PSB) can not only improve plant growth but also inhibit the transportation of metals to roots. However, data on gene expression in PSB Burkholderia sp. strain 'N3' and grafted watermelon plants dealing with Cd remain to be elucidated. In this study, core genes and metabolic pathways of strain 'N3' and grafted plants were analyzed by Illumina sequencing. Results showed that 356 and 2527 genes were upregulated in 'N3' and grafted watermelon plants, respectively, whereas 514 and 1540 genes were downregulated in 'N3' and grafted watermelon plants, respectively. Gene ontology enrichment analysis showed that signal transduction, inorganic ion transport, cell motility, amino acid transport, and metabolism pathways were marked in 'N3'. However, pathways such as secondary metabolite biosynthesis, oxidation–reduction process, electron transfer activity, and channel regulator activity were marked in the grafted plants. Six genes related to pentose phosphate, glycolysis, and gluconeogenesis metabolism were upregulated in the grafted plants. This study paves the way for developing potential strategies to improve plant growth under Cd toxicity. [ABSTRACT FROM AUTHOR]

[Objective] The paper aimed to reveal the community structure and species diversity of soil bacteria in different habitats of the Sichuan section of Zoige National Natural Park. [Method] The study employed high-throughput sequencing technology to study the diversity and community structure of soil bacteria in the soils from five different habitats (subalpine meadow soil, cinnamon soils, bog soils, aeolian soils and meadow soils) in the Sichuan section of Zoige National Park and discussed the relationship between soil physicochemical properties and microbial community structure. [Result] (i) The taxonomic analysis of soil bacteria revealed the identification of 36 phyla, with the dominant bacteria encompassing Actinobacteriota, Proteobacteria, Firmicutes, Acidobacteriota and Chloroflexi. (ii) In a-diversity analysis, subalpine meadow soils (YGS) showed the highest Chaol, Observed Species, Shannon and Simpson index, indicating the highest bacterial community richness and diversity in soil. (iii) In ẞ-diversity analysis, the high overlap among cinnamon soils (HT), bog soils (ZZT), YGS and aeolian soils (ST) suggested a similar composition of bacterial communities among these four soil types in the region, while meadow soils (CD) bacteria community showed significant differences (P<0.05). (iv) In RDA redundancy analysis of different habitats, Actinobacteriota showed a positive correlation with soil pH; Proteobacteria showed a positive correlation with soil pH and total potassium (TK); Firmicutes showed significant positive correlations with soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP) and moisture content (MC). [Conclusion] The research results reveal that the differences in the composition and diversity of soil bacterial communities in different habitats of the Sichuan section of Zoige National Natural Park, as well as the strong correlation of these differences with environmental factors. The finding not only contributes to a deeper understanding of soil microbial ecology but also provides a scientific basis for the management of soil ecosystems. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi have huge potential value, both nutritionally and economically, but most of them cannot be cultivated artificially. To better understand the influence of abiotic and biotic factors upon the growth of ectomycorrhizal fungi, mycosphere soil and bulk soil of five ectomycorrhizal fungi (Calvatia candida, Russula brevipes, Leucopaxillus laterarius, Leucopaxillus giganteus, and Lepista panaeola) were used as research objects for this study. Illumina MiSeq sequencing technology was used to analyze the community structure of the mycosphere and bulk soil bacteria of the five ectomycorrhizal fungi, and a comprehensive analysis was conducted based on soil physicochemical properties. Our results show that the mycosphere soil bacteria of the five ectomycorrhizal fungi are slightly different. Escherichia, Usitatibacter, and Bradyrhizobium are potential mycorrhizal-helper bacteria of distinct ectomycorrhizal fungi. Soil water content, soil pH, and available potassium are the main factors shaping the soil bacterial community of the studied ectomycorrhizal fungi. Moreover, from the KEGG functional prediction and LEfSe analysis, there are significant functional differences not only between the mycosphere soil and bulk soil. 'Biosynthesis of terpenoidsand steroids', 'alpha-Linolenic acid metabolism', 'Longevity regulating pathway-multiple species', 'D-Arginine and D-ornithine metabolism', 'Nitrotoluene degradation' and other functions were significantly different in mycosphere soil. These findings have pivotal implications for the sustainable utilization of ectomycorrhizal fungi, the expansion of edible fungus cultivation in forest environments, and the enhancement of derived economic benefits. [ABSTRACT FROM AUTHOR]

Nature reserves are crucial for protecting biological habitats and maintaining biodiversity. Soil bacterial community plays an irreplaceable role in the structure and function of ecosystem. However, the impact of nature reserves on soil bacterial communities is still unclear. To explore the effects of desert grassland nature reserve management on soil microbial communities, we compared the differences in soil bacterial community composition, α-diversity and community structure inside and outside a desert grassland nature reserve, and explored the correlation between soil bacterial communities and plant biomass and soil chemical index. We found that (1) the relative abundance of Acidobacteriota is highest in the soil both inside and outside the nature reserve in shrub grassland; (2) the Chao1 index of soil bacterial communities in the core protected zone and general control zone of the reserve was significantly higher than that outside the reserve (p  <  0.05) in the shrub grassland. Similarly, in the herbaceous grassland, the Shannon index of soil bacterial communities was significantly higher in the core protected zone of the reserve than that outside the reserve (p  <  0.05). (3) While we found no significant difference in soil bacterial community structure between inside and outside the reserve in the shrub grassland, we found that the soil bacterial community structure in the core protected zone was significantly different from that outside the reserve in the herbaceous grassland (p  <  0.05); (4) we also found that higher plant productivity and soil nutrients promoted most soil dominant bacterial phyla, while higher soil pH and salinity inhibited most soil dominant bacterial phyla. Our findings thus help better understand the influencing factors of and the mechanisms behind variation in soil bacterial communities inside and outside desert grassland nature reserves. [ABSTRACT FROM AUTHOR]

Plants and insect herbivores are two of the most diverse multicellular groups in the world, and both are strongly influenced by interactions with the belowground soil microbiome. Effects of reciprocal rapid evolution on ecological interactions between herbivores and plants have been repeatedly demonstrated, but it is unknown if (and how) the soil microbiome could mediate these eco‐evolutionary processes on a shared host plant. We tested the role of a plant‐beneficial soil bacterium Acidovorax radicis in altering eco‐evolutionary interactions between different aphid genotypes (Sitobion avenae, genotypes Sickte and Fescue) feeding on barley Hordeum vulgare. We measured fecundity, longevity and population growth of two aphid genotypes reared separately or together (population mixture) on three different barley varieties that were inoculated with or without A. radicis. Results showed that across all plant varieties A. radicis increased plant growth and suppressed aphid populations via reduced longevity and fecundity. The strength of effect was dependent on aphid genotype and barley variety, while the direction of effect was altered by aphid population mixture. Using Lotka–Volterra modelling, we demonstrated that while A. radicis inoculation decreased growth rates for both aphid genotypes it increased the competitiveness of one genotype against the other. In general, in the presence of A. radicis, the Fescue aphid genotype became more inhibitory of Sickte aphids, while Sickte aphids facilitated the growth of Fescue aphids. Our work demonstrates that plant rhizosphere microbiomes exert community‐level influences by mediating eco‐evolutionary interactions between herbivores and host plants. By altering competitive interaction outcomes among aphids and thus impacting processes such as rapid evolution, soil microbes contribute to the short‐ and long‐term structure and functioning of terrestrial habitats. [ABSTRACT FROM AUTHOR]

The lipid-producing gram-positive bacteria were isolated from soil and it was identified as Streptomyces fradiae JJ1 MK733985.1. Bacterial lipid synthesis was explored using rice washed water through the fermentation research. The exponential growth phase was reached on the fifth day of fermentation, according to the results. The ability of Streptomyces fradiae to produce microbial oil was compared to that of International Streptomyces Project-2 Medium (ISP2) medium. The results showed that RWW culture medium yielded 85.4% fatty acids and 60.3 g/L biomass, while ISP2 medium yielded 83.2% wt fatty acids and 59.5 g/L biomass. The microbial oil was transesterified into Fatty acid methyl esters (FAME), and its characteristics were studied using American Society for Testing Materials (ASTM) standards. The specific gravity was 0.864, the density was 0.863, the gross heating value was 42498 kj/kg, the cetane number was 37, and the acid value was 0.46. Streptomyces fradiae grew with an ISP2 density of 0.835, specific gravity of 0.845, gross heating value of 42326 kj/kg, and acid value of 0.43. According to the findings, Streptomyces fradiae isolated from soil can grow in RWW medium for the first time and provide the same yield as commercial media while being significantly less expensive. [ABSTRACT FROM AUTHOR]

Paulownia fortunei, one of the world's fastest growing timber tree species, is universally applied with fertilizer as a management approach to meet the nutrient requirements for efficient cultivation. The substantial effects of fertilizer on soil microorganisms in Paulownia plantations have been empirically tested; however, the successive chronosequence of soil microbial carbon and nitrogen functional genes under different fertilizer application durations remains limited. The objective of this study was to explore the characteristics of soil microorganisms involved in carbon and nitrogen cycling and greenhouse gas (GHG) production under different fertilizer application durations. Different fertilizer treatments, i.e., the short-term group (SG) versus the long-term group (LG), and durations were applied to subtropical plantations in southern China and compared with zonal evergreen broad-leaved forests. Results showed that fertilizer treatment significantly increased the relative abundance of Acidobacteriota and the expression of nirK and nosZ. The functional groups that dominated metabolism in SG and LG treatments belonged to Actinobacteria and Acidobacteriota, respectively, suggesting that the nutrient preference of microorganisms in forest soil may change from copiotrophs to oligotrophs with increasing fertilizer application duration. Correlation network analysis showed that the communities that dominated the carbon and nitrogen cycles belonged to Actinobacteria and Acidobacteriota, respectively, and were closely related to ammonium nitrogen and available iron. Actinobacteria and Acidobacteriota were likely the major taxa that affected soil GHG production under different fertilizer application durations. We concluded that long-term fertilizer use changed the preference of microbial nutrient uptake into recalcitrant nutrients, and the sensitivity of the microbial community to nutrients gradually decreased with increasing fertilizer application time. The dominant Actinobacteria affected soil carbon and nitrogen cycles largely by stimulating denitrification to increase the release of nitrous oxide, which might lead to the loss of nitrogen components and the intensification of the GHG effect with increasing fertilizer application time. [ABSTRACT FROM AUTHOR]

Agroforestry systems such as Taungya are sustainable alternatives for the recovery of degraded areas and profitability with commercial plantations, providing improvements in soil physical, chemical, and biological properties. In this context, African mahogany (Khaya ivorensis A. Chev) emerges as an important forest species in Brazil, with the potential for intercropping. The objective of this study was to evaluate the growth and economic return from the Taungya system compared to K. ivorensis monoculture in a degraded area in the humid tropics. Three planting systems were studied: T1, monoculture (K. ivorensis); T2, K. ivorensis + 1st cycle with Zea mays + 2nd cycle with Manihot esculenta; T3, K. ivorensis + 1st cycle with Vigna unguiculata + 2nd cycle with Zea mays. The survival, growth, and relative increments in plant height and stem diameter were determined for the three management systems. Productivity of the agricultural crops was quantified, and bacteriological analyses of the soil and economic systems were performed. The Taungya system with bean and corn crops provided greater growth of K. ivorensis, in addition to a greater density of total bacteria in the soil and provided a higher level of soil conditioning. In these systems, the cultivation and sale of agricultural crops can amortize the total cost of planting and maintenance of plantations with forest species, especially if family labor is considered. However, the completion of additional agricultural cycles may further amortize these investments. [ABSTRACT FROM AUTHOR]

Soil bacteria are an important part of the forest ecosystem, and they play a crucial role in driving energy flow and material circulation. Currently, many uncertainties remain about how the composition and distribution patterns of bacterial communities change along altitude gradients, especially in forest ecosystems with strong altitude gradients in climate, vegetation, and soil properties. Based on dynamic site monitoring of the Baiyun Mountain Forest National Park (33°38′–33°42′ N, 111°47′–111°51′ E), this study used Illumina technology to sequence 120 soil samples at the site and explored the spatial distribution mechanisms and ecological processes of soil bacteria under different altitude gradients. Our results showed that the composition of soil bacterial communities varied significantly between different altitude gradients, affecting soil bacterial community building by influencing the balance between deterministic and stochastic processes; in addition, bacterial communities exhibited broader ecological niche widths and a greater degree of stochasticity under low-altitude conditions, implying that, at lower altitudes, community assembly is predominantly influenced by stochastic processes. Light was the dominant environmental factor that influenced variation in the entire bacterial community as well as other taxa across different altitude gradients. Moreover, changes in the altitude gradient could cause significant differences in the diversity and community composition of bacterial taxa. Our study revealed significant differences in bacterial community composition in the soil under different altitude gradients. The bacterial communities at low elevation gradients were mainly controlled by stochasticity processes, and bacterial community assembly was strongly influenced by deterministic processes at middle altitudes. Furthermore, light was an important environmental factor that affects differences. This study revealed that the change of altitude gradient had an important effect on the development of the soil bacterial community and provided a theoretical basis for the sustainable development and management of soil bacteria. [ABSTRACT FROM AUTHOR]

The Songnen grassland is an important resource for livestock production in China. Due to the intensification of anthropogenic activities in recent years, vegetation degradation has worsened, and the salinization of grassland has become increasingly serious, which severely affects the sustainable development of grassland animal husbandry. In this study, organic fertilizer addition was carried out at saline-and-alkaline-degraded Songnen grassland sites with photovoltaic panels, and we investigated the effects of organic fertilizer treatments on the vegetation and soil bacteria in these areas. The results showed that both organic fertilizer treatments increased the community composition and diversity indices of plants (p < 0.05); they also had significant effects on soil electrical conductivity and rapidly available potassium (p < 0.05). In the dominant phylum of bacteria, the relative abundance of Firmicutes increased without adding organic fertilizer under the photovoltaic panel; the addition of organic fertilizer had a significant effect on the relative abundance of Firmicutes and Desulfobacterota (p < 0.05), reducing their relative abundance, respectively. There were differences in the number of bacteria at the genus level under different treatments compared to the control, with the highest enrichment of bacteria occurring at the OFE position, and a significant difference (p < 0.05) being found between the control and the other four groups at the genus level of g_norank_f_norank_o_Actinomarinales. Organic fertilizer had a significant effect on the bacterial Simpson diversity index, with the most significant increasing trend found in OFE (the front eaves of the photovoltaic panel in fertilization area). The results of a correlation analysis showed that pH, electrical conductivity, and total nitrogen were the main factors affecting the soil bacterial community. [ABSTRACT FROM AUTHOR]

Salinity negatively impacts soil fertility by impairing the development and physiological functions of foxtail millet plants. Organic amendments have emerged as a viable solution in the reclamation and management of salinity inflicted soils and improve the performance of crop. In this regard, a pot experiment was carried out to examine the effect of organic amendments (OAs) on soil quality and its influence on the growth and physiology of foxtail millet under saline and non-saline condition. The findings indicated that under salt stress conditions, the levels of proline, hydrogen peroxide (H2O2), and electrolyte leakage (EL) risen, whilst other physiological parameters decrease in foxtail millet. However, the addition of OAs, particularly dhaincha and biochar (BC), has shown a promising salt tolerant amendment among others. Its addition improved the growth performance of salinity-stressed plants, including plant height, fresh and dry biomass, simultaneously decreased sodium ion (Na+) and improved calcium (Ca2+), potassium (K+), and nitrate ion (NO3−). They also increased proline build up by 6–17 %, reduced H2O2 (19–38 %) and malondialdehyde (16–18 %). Furthermore, they elevated the relative water content (RWC) (25 %), chlorophyll content, and reduced EL (29–50 %). Once more, dhaincha and BC enhanced the number of rhizobia, phosphorus-solubilizing bacteria (PSB) and overall bacterial population in the soil. In saline soil, daincha and BC could enhance soil organic matter (628 %), total nitrogen (1630 %), available phosphorus (32–38 %), and exchangeable potassium (54–73 %). A potential strategy for improving setaria italica performance under salt is suggested to be the following order, dhaincha > biochar > vermicompost > duckweed. The study would assist stakeholders in these salinity-prone areas in strategizing the use of OAs to their fallow land for cultivation and agricultural activities.

Rainforests provide vital ecosystem services that are underpinned by plant–soil interactions. The forests of Borneo are globally important reservoirs of biodiversity and carbon, but a significant proportion of the forest that remains after large-scale agricultural conversion has been extensively modified due to timber harvest. We have limited understanding of how selective logging affects ecosystem functions including biogeochemical cycles driven by soil microbes. In this study, we sampled soil from logging gaps and co-located intact lowland dipterocarp rainforest in Borneo. We characterised soil bacterial and fungal communities and physicochemical properties and determined soil functioning in terms of enzyme activity, nutrient supply rates, and microbial heterotrophic respiration. Soil microbial biomass, alpha diversity, and most soil properties and functions were resistant to logging. However, we found logging significantly shifted soil bacterial and fungal community composition, reduced the abundance of ectomycorrhizal fungi, increased the abundance of arbuscular mycorrhizal fungi, and reduced soil inorganic phosphorous concentration and nitrate supply rate, suggesting some downregulation of nutrient cycling. Within gaps, canopy openness was negatively related to ectomycorrhizal abundance and phosphomonoesterase activity and positively related to ammonium supply rate, suggesting control on soil phosphorus and nitrogen cycles via functional shifts in fungal communities. We found some evidence for reduced soil heterotrophic respiration with greater logging disturbance. Overall, our results demonstrate that while many soil microbial community attributes, soil properties, and functions may be resistant to selective logging, logging can significantly impact the composition and abundance of key soil microbial groups linked to the regulation of vital nutrient and carbon cycles in tropical forests.

In p-MFCs living plants photosynthesize within a bio-electrochemical circuit. The plant exudes organic waste material from the roots. In the rhizosphere, bacteria consume these wastes by oxidizing them in contrast to the atmosphere that reduces it. This redox reaction along with photosynthesis can be harnessed as bioelectricity. In this work, the plant Withania somnifera (L.) Dunal was used for generating bioelectricity from the root exudates and organic matter available in the soil. An open circuit voltage of 930±21 mV was achieved between multiple cycles of operation. The cell voltage further increased to 1260±140 mV with enrichment in the form of discards from vegetable matter. The peak recorded voltage was 1400 mV. Graphite fibre felt electrodes ensured uniform microbial growth with power densities that were achieved at 57 mW/m2 and 84 mW/m2 with and without enrichment respectively. ATR-FTIR demonstrated complete degradation of specific compounds attached to the carbon matrix in the soil along with the polysaccharide content from the enrichments. Additionally, this work also monitored the changes in soil pH and its homogeneity, the impact of photosynthetically active radiation, humidity, and the presence of CO2 in the air, and how it affects plant growth and ultimately the microbes at the rhizosphere which accounted for the bioremediation and the resultant bioelectricity production. SEM imaging provided additional evidence that the presence of electrochemically active soil bacteria, an anaerobic environment, and electrode characteristics are crucial for the development of conductive biofilms.

Abstract Background The rhizosphere environment regulated by root secretory activity and rhizosphere microbial interactions plays an essential role in resisting soil-borne diseases, while the host species is an important factor that affects the composition of root exudates and rhizosphere microbiomes. However, few studies have been done on the characteristics of root exudates and bacterial communities in terms of composition, diversity, and functional potential when host plants of different species are subjected to the same disease. Results In this study, we examined the rhizosphere soil bacteria and root exudates of both healthy and diseased tomatoes and peppers employing metabolomics and amplicon techniques. Our findings indicated that variations existed in both root exudates and the bacterial community among different host species and health states. The diversities of both rhizosphere metabolites and bacterial communities were significantly reduced in different diseased plants. Although pepper and tomato resisted the invasion of Ralstonia by recruiting different potentially beneficial bacteria, their rhizosphere bacterial communities had the same functional potential. In comparison to diseased rhizosphere soil, healthy rhizosphere soil had many more functional pathways associated with disease suppression and plant growth. Conclusions This study highlighted the crucial role of host plants in shaping the rhizosphere environment and revealed the variation characteristics of root exudates and rhizosphere bacteria of different host plants induced by the same disease. Graphical Abstract

A rapidly increasing human population coupled with climate change and several decades of over-reliance on synthetic fertilizers has led to two pressing global challenges: food insecurity and land degradation. Therefore, it is crucial that practices enabling both soil and plant health as well as sustainability be even more actively pursued. Sustainability and soil fertility encompass practices such as improving plant productivity in poor and arid soils, maintaining soil health, and minimizing harmful impacts on ecosystems brought about by poor soil management, including run-off of agricultural chemicals and other contaminants into waterways. Plant growth promoting bacteria (PGPB) can improve food production in numerous ways: by facilitating resource acquisition of macro- and micronutrients (especially N and P), modulating phytohormone levels, antagonizing pathogenic agents and maintaining soil fertility. The PGPB comprise different functional and taxonomic groups of bacteria belonging to multiple phyla, including Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, among others. This review summarizes many of the mechanisms and methods these beneficial soil bacteria use to promote plant health and asks whether they can be further developed into effective, potentially commercially available plant stimulants that substantially reduce or replace various harmful practices involved in food production and ecosystem stability. Our goal is to describe the various mechanisms involved in beneficial plant-microbe interactions and how they can help us attain sustainability.

Aim: Species–area relationships (SAR) are widely utilized for estimating the species richness and its spatial turnover across various scales. Despite the prevalent characterization of SAR using the power law in many microbial community studies, its efficacy remains unvalidated. This study aims to characterize the microbial SAR and its mechanisms in alpine grassland soils on the Qinghai‐Tibet Plateau (QTP). Location: Qinghai‐Tibet Plateau, China. Time Period: August 2014. Major Taxa Studied: Soil bacteria. Methods: Soil samples were collected from five alpine grassland sites on the QTP. Employing a nested sampling strategy at each site, soil samples were collected in plot sizes ranging from 0.5 × 0.5 m2 to 2048 × 2048 m2. Soil bacterial communities were analysed by sequencing 16S ribosomal RNA gene amplicons using an Illumina MiSeq. Results: The bacterial SAR exhibited a logarithmic power law (R2: 0.952–0.999), outperforming the power law (R2: 0.701–0.852). Consequently, the most widely adopted power law led to an overestimation of species richness by up to 15.07% in areas >256 × 256 m2, and the regional maximum theoretical richness based on Chao1 by up to 9.88%. Mechanistically, the passive sampling hypothesis was refuted through the rarefied species richness analysis, and the disproportionate effect hypothesis was rejected based on analyses of the effective numbers of species number conversions for the probability of interspecific encounters (SPIE). Notably, Pearson and multiple linear regression analyses indicated that the spatial turnover of bacterial richness was determined by the environmental heterogeneity (R2: 0.855–0.999), rather or better than environmental variables themselves, supporting the 'environment heterogeneity hypothesis'. Main Conclusions: Soil bacterial SAR in alpine grasslands exhibited a logarithmic power relationship. Spatial turnover was primarily governed by the environmental heterogeneity. In contrast, the traditional power law leads to an overestimation of soil bacterial diversity at the regional scale. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mineral mining often results in changes to the soil environment, reducing the sustainability of the surrounding environment. Restoring the physical and chemical properties of soil in post‐tin‐mining areas on the tropical island of Belitung, Indonesia, has been a laborious process after more than 10 decades of land reclamation. We aimed to determine which parameter of the soil properties was responsible for the slow recovery process and if there were other properties that indicated more rapid changes. We measured the physical, chemical, and biological properties of soils of different periods in the post‐tin‐mining areas. We sampled soil from three areas: 0, 1, and 6 years after mining and an adjacent natural forest as a reference site. The soil water content, hydraulic conductivity, bulk density, particle distribution, mineral content, and soil microbial composition were measured in the field and analyzed in the laboratory. The soil showed a fine particle loss and despite the absence of clay, water‐holding capacity was significantly increased in the 6‐year‐old soil. Organic carbon increased by 0.2% after 6 years of reclamation. Copper, iron, manganese, and zinc in the soils fluctuated less. Minimal amounts of Pb and Cd were found. Soil bacterial communities shift with land age. Actinobacteria were dominant a few years after mining, while Proteobacteria colonized the mined area after 6 years. This study examined the more profound changes in the soil properties of tropical post‐tin‐mined land. Soil and bacterial characteristics can be used as markers to monitor the progress of land rehabilitation. [ABSTRACT FROM AUTHOR]

Industrial activities destroying natural resources for decades have been one of the most significant factors in environmental destruction. As a result of industrialization, environmental pollutants became one of the biggest threats for the biosphere. Heavy metals, one of these environmental pollutants, have become a significant health threat for organisms by forming metal accumulations in water and soil. In addition to the existing ones, most researchers believe that there is a great need for alternative biological processes to be used in the control of heavy metal pollution. Bioremediation is the process of removing various toxic pollutants, such as heavy metals from the environment, especially with the help of fungal and bacterial microorganisms, sometimes plants and earthworms. The use of bacteria in the bioremediation process is prevalent. In this study, the metal tolerance and plant growth-promoting properties of Bacillus mycoides and Bacillus thuringiensis isolated from the root soil of and orchid plant were investigated. The abilities of both bacteria to tolerate copper, lead, iron, silver, and zinc were tested in addition to and their indole acetic acid production (IAA), siderophore production, phosphate solubility and Aminocyclopropane-1-Carboxylate-deaminase (ACC-deaminase) activity were determined. The two isolates exhibited a high level of tolerance towards different pH levels, temperature ranges and metal concentrations. The results showed that B. mycoides and B. thuringiensis isolates can be used as bioremidant agents in metal-contaminated soils and also as biological fertilizers due to their plant growth-promoting properties. [ABSTRACT FROM AUTHOR]

One of the main problems in current agriculture is the reduction of chemical fertilizers by replacing them with biofertilizers composed of beneficial microorganisms for soils and plants. Therefore, the present work aims to evaluate the effect of Pseudoxanthomonas indica named H32, previously isolated from healthy tomato plants rhizosphere, on the growth, development and yield of chard, carrot and radish crops. To this end, its ability to produce indoleacetic acid (IAA) was determined. In addition, its property to solubilizing insoluble phosphate in Pikovskaya-agar medium. The seeds were inoculated by soaking in a H32 cells suspension with 105 UFC/mL in 0.1 % carboxymetyl cellulose solution, for 3 h. A similar procedure using only carboxymetyl cellulose solution was done for non-inoculated seeds. All Seeds were then sown in 1 x 10 m plots. H32 was inoculated around the root of the seedlings of inoculated seeds, seven days after germination. The results showed that plants from inoculated seeds had greater humid weight, greater height, and roots with greater length and weight than plants from non-inoculated seeds (P < 0.01). The inoculation of the seeds and soil with H32 increased the yield by 19 % for radish, 88.7 % and 68.5 % for chard and carrot, respectively. These results show that Pseudoxanthomonas indica H32 has potential for use as a growth promoter in the crops studied. [ABSTRACT FROM AUTHOR]

Permafrost is widely degraded in the context of global warming. The spatial distribution of soil microbes in these cold habitats has received a lot of attention. However, knowledge on the changes in permafrost microbial communities following permafrost thaw is still limited. We used permafrost soil from a taiga forest for indoor experiments using pristine soil as a control (CK, −2 °C), simulating warming for 15 days at temperatures of 0 °C (T1), 2 °C (T2), and 4 °C (T3). Amplicons of the hypervariable V4 region of the bacterial 16S rRNA gene were sequenced to identify bacterial communities present in the soils of pristine and warming treatments. Warming increased the average relative abundance of Proteobacteria (5.71%) and decreased that of Actinobacteriota (7.82%). The Beta diversity changed (p = 0.001) and significantly correlated with the pH, microbial biomass carbon (MBC), and available potassium (AK) of the soil (p < 0.05). Warming further increased the Alpha diversity (Simpson index), changing the functional pathways of the bacterial communities, whereby secondary functional pathways produced significant correlations with bacterial phyla (p < 0.05). Combined, the results indicated that short-term warming altered the Beta diversity of soil bacteria in a taiga forest's permafrost soil by decreasing the abundance of Actinobacteria and increasing that of Ascomycetes, while pH, MBC, and AK were identified as the soil factors influencing the structure and diversity of the bacterial communities. [ABSTRACT FROM AUTHOR]

Forest fires are among the most influential drivers of changes in forest soil bacterial diversity. Nevertheless, little is known regarding the effects of forest fires on maintaining the complex interactions that preserve forest ecosystem stability. Therefore, this study characterized alterations in soil bacterial community composition and diversity within taiga forests subjected to varying disturbance intensities. Particularly, this study examined the bacterial community within a Larix gmelinii fire-burnt site in Daxinganling, analyzing the changes in bacterial community structure and function across light, moderate, and heavy fire-burnt sites, as well as a control sample site, utilizing Illumina MiSeq technology. Through an assessment of bacterial community diversity and soil physicochemical properties (moisture content (MC), pH, microbial biomass carbon (MBC), organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), and available potassium (AP)), we explored the influence of the soil microenvironment on the soil bacterial community structure at the burnt site under different disturbance intensities. Our findings demonstrated that (1) there was no significant change in the Chao index of soil bacteria in the burnt site under different disturbance intensities, whereas the Shannon index decreased significantly (p < 0.05) and the Simpson index increased significantly (p < 0.05) in the burnt site under light and moderate disturbance. (2) The relative abundance of dominant phyla, such as Proteobacteria, Proteobacteria, and Actinobacteriota, did not change significantly in the fire-burnt site under different disturbance intensities, whereas rare species, such as Acidipila, Occallatibacter, and Acidibacter, experienced a significant increase in relative abundance at the genus level. (3) The results of principal coordinates analysis (PCoA) and canonical correlation analysis (CCA) revealed significant differences in the Beta diversity of soil bacteria in the fire-burnt site under varying interference intensities. The Beta diversity of soil bacteria exhibited significant differences (p = 0.001), with MC, pH, TN, AN, and AK identified as significant influencing factors. (4) FAPROTAX functional prediction analyses were conducted to assess the changes in soil bacteria involved in Cellulolysis, Chemoheterotrophy, and Aerobic_Chemoheterotrophy in the fire-burnt site, with the relative abundance of bacteria involved in Chemoheterotrophy being significantly increased (p < 0.05) under different disturbance intensities. Collectively, our findings demonstrated that different disturbance intensities caused by fires significantly affected the Alpha diversity, Beta diversity, and functional abundance of soil bacterial communities in taiga forests, with MC, pH, TN, AN, and AK being identified as key influencing factors. Additionally, the presence of numerous rare species suggests their role as pioneer communities in the succession of soil bacterial communities. [ABSTRACT FROM AUTHOR]

Soil microorganisms are vital components of the karst terrestrial ecosystem. However, their responses to the vegetation succession on karst mountain peaks remain unclear as to whether soil microbial diversity and community compositions change with vegetation succession. We investigated the diversity and community compositions of soil bacteria and fungi and associated environmental factors along a vegetation succession from moss crusts (MC) to moss crusts with sparse grasses (MCG) to sparse grasses (G) on karst mountain peaks. The results indicated that soil organic carbon and total nitrogen generally increased, and soil pH changed in the range of 8.19–8.44 and slightly declined with vegetation succession. Overall, there was an increase in microbial biomass along the vegetation succession, with the dominant phyla of bacteria, including Proteobacteria, Acidobacteria, Actinobacteria, Choroflexi, Gemmatiomnadates, Bacteroidetes, and Planctomycetes, and the dominated phyla of fungi, including Basidiomycota and Ascomycota. Notably, both the bacterial and fungal community compositions were different among the three successional stages. Spearman's correction analysis showed that soil organic carbon and total nitrogen had stronger and more significant influences on the soil microbial community compositions compared to soil water content, pH, and C:N ratio. Overall, our results provide evidence for the changes and influencing factors of the microbial community with the succession vegetation on karst mountain peaks. [ABSTRACT FROM AUTHOR]

Here, phytoremediation studies of toxic metal and organic compounds using plants augmented with plant growth-promoting bacteria, published in the past few years, were summarized and reviewed. These studies complemented and extended the many earlier studies in this area of research. The studies summarized here employed a wide range of non-agricultural plants including various grasses indigenous to regions of the world. The plant growth-promoting bacteria used a range of different known mechanisms to promote plant growth in the presence of metallic and/or organic toxicants and thereby improve the phytoremediation ability of most plants. Both rhizosphere and endophyte PGPB strains have been found to be effective within various phytoremediation schemes. Consortia consisting of several PGPB were often more effective than individual PGPB in assisting phytoremediation in the presence of metallic and/or organic environmental contaminants. [ABSTRACT FROM AUTHOR]

Soil is a vital ecosystem for various life forms, including bacteria. Bacteria are the main group of soil microbes, mostly because of their ability to produce various extracellular enzymes. Amylases are the enzymes that break down starch, which are essential in biotechnology industries such as food, fermentation, textiles, and paper manufacturing. The demand for amylase is often high since many enterprises do not have access to local supplies of the enzyme. The objective of the current investigation is to isolate and identify bacterial isolates that can produce the enzyme amylase from soil samples. Soil samples were collected from the unexplored Biligiriranga hills (11.9988° N, 77.1398° E) in south-western Karnataka Bacterial isolates were isolated from soil samples and were primarily screened on starch agar medium to determine the amylase production. Three out of fifteen bacterial isolates that produced amylase were selected based on the highest clear zone around the bacterial colony. These three bacterial isolates were identified both microscopically and biochemically. Gram staining demonstrated that the isolates are rod-shaped and gram-positive organisms. Biochemical studies indicated that the isolates were positive for the catalase and starch hydrolysis tests, whereas negative for the potassium hydroxide and methyl red tests. Besides, 16S rRNA gene amplification and sequencing confirmed the isolate as Bacillus subtilis. The 16S rRNA sequence of B. subtilis strain B has been deposited in the NCBI GenBank. The optimal growth conditions observed in B. Subtilis. The optimal growth conditions observed in B. Subtilis were 37° C temperature at pH 7 and incubation period for 37h. Thus, the isolation and identification of soil-derived amylase-producing bacteria are crucial for understanding their potential applications in various industrial processes, such as bioremediation, waste management, and the production of enzymes for food, pharmaceuticals, and biofuel industries. [ABSTRACT FROM AUTHOR]

A study was conducted to determine the changes in bacterial micro flora of soil in relation to fallowing (abandonment) in rice fields. Soil samples from two paddy fields at Kumarakom region, southwest part of Kuttanad, Kerala, one field with paddy cultivation and the other fallowed, was subjected to the study. A total of 15 bacterial species, 8 from the cultivated field only, 6 from the fallowed field only and 1 common to both fields were isolated and identified in the study. The bacterial community in the soil of uncultivated field are entirely shifted from field where rice has been cultivated continuously. The persistent occurrence encountered in the cultivated field isolates were Bacillus megaterium, Pseudomonas aeroginosa and Klebsiella oxytoca while that in the abandoned field were of E coli followed by higher incidence of (80%) Enterobacter aerogenes and Citrobacter freundii. Under rice cultivation, soil pH, EC and bacterial density were generally higher than that in uncultivated soils while organic carbon in the soil was consistently lower than that in uncultivated soils. The study reveals the importance of bacteria in maintaining the health of a habitat and confirm that soil quality deteriorates over long-term fallowing. [ABSTRACT FROM AUTHOR]

This study aimed to isolate biosurfactant‐producing and hydrocarbon‐degrading actinomycetes from different soils using glycerol–asparagine and starch–casein media with an antifungal agent. The glycerol–asparagine agar exhibited the highest number of actinomycetes, with a white, low‐opacity medium supporting pigment production and high growth. Biosurfactant analyses, such as drop collapse, oil displacement, emulsification, tributyrin agar test, and surface tension measurement, were conducted. Out of 25 positive isolates, seven could utilize both olive oil and black oil for biosurfactant production, and only isolate RP1 could produce biosurfactant when grown in constrained conditions with black oil as the sole carbon source and inducer, demonstrating in situ bioremediation potential. Isolate RP1 from oil‐spilled garden soil is Gram‐staining‐positive with a distinct earthy odor, melanin formation, and white filamentous colonies. It has a molecular size of ~621 bp and 100% sequence similarity to many Streptomyces spp. Morphological, biochemical, and 16 S rRNA analysis confirmed it as Streptomyces sp. RP1, showing positive results in all screenings, including high emulsification activity against kerosene (27.2%) and engine oil (95.8%), oil displacement efficiency against crude oil (7.45 cm), and a significant reduction in surface tension (56.7 dynes/cm). Streptomyces sp. RP1 can utilize citrate as a carbon source, tolerate sodium chloride, resist lysozyme, degrade petroleum hydrocarbons, and produce biosurfactant at 37°C in a 15 mL medium culture, indicating great potential for bioremediation and various downstream industrial applications with optimization. [ABSTRACT FROM AUTHOR]

Background: The rhizosphere environment regulated by root secretory activity and rhizosphere microbial interactions plays an essential role in resisting soil-borne diseases, while the host species is an important factor that affects the composition of root exudates and rhizosphere microbiomes. However, few studies have been done on the characteristics of root exudates and bacterial communities in terms of composition, diversity, and functional potential when host plants of different species are subjected to the same disease. Results: In this study, we examined the rhizosphere soil bacteria and root exudates of both healthy and diseased tomatoes and peppers employing metabolomics and amplicon techniques. Our findings indicated that variations existed in both root exudates and the bacterial community among different host species and health states. The diversities of both rhizosphere metabolites and bacterial communities were significantly reduced in different diseased plants. Although pepper and tomato resisted the invasion of Ralstonia by recruiting different potentially beneficial bacteria, their rhizosphere bacterial communities had the same functional potential. In comparison to diseased rhizosphere soil, healthy rhizosphere soil had many more functional pathways associated with disease suppression and plant growth. Conclusions: This study highlighted the crucial role of host plants in shaping the rhizosphere environment and revealed the variation characteristics of root exudates and rhizosphere bacteria of different host plants induced by the same disease. [ABSTRACT FROM AUTHOR]

To explore the changes of soil bacterial diversity and community composition in tobacco–rice rotation soil under different straw return methods, control (CK), amendment (BP), undisturbed straw return (S0), straw–cow manure compost return (S1), straw–rapeseed cake compost return (S2), and these combined with amendment (S0BP, S1BP, S2BP) conditions were set up in a tobacco–rice rotation pot experiment. The composition of the soil bacterial community was analyzed using 16S rRNA high-throughput sequencing technology. The results of the experiment showed that direct straw return and straw return with amendment can effectively improve soil physical and chemical properties. Straw return combined with amendments significantly increased bacterial community abundance. The S1BP treatment resulted in the highest bacterial community abundance. Each treatment had no significant effect on the soil bacterial community diversity index. Proteobacteria (16.42%-26.01%), Chloroflexi (15.62%-20.46%), Acidobacteriota (8.71%-15.86%), Actinobacteriota (7.08%- 11.47%) and Firmicutes (7.29%-11.74%) were the predominant phyla of soil bacterial communities. However, straw return significantly increased the relative abundances of Proteobacteria and Bacteroidota. Compared with straw return, the straw return with amendment treatments significantly increased the relative abundances of Bacteroidota and Desulfobacterota but markedly decreased the abundances of Acidobacteriota and Actinobacteriota. Furthermore, soil pH, minimum water holding capacity, soil porosity, available potassium, dissolved organic carbon, and microbial biomass carbon content were the main factors affecting bacterial community structure, which had a positive correlation with Desulfobacterota, Proteobacteria, and Bacteroidota but a negative correlation with Nitrospirota, Actinobacteriota, Acidobacteriota, and Armatimonadota. In summary, returning tobacco and rice straw directly or in combination with amendments can improve soil physicochemical properties and increase the abundance of soil bacterial communities. [ABSTRACT FROM AUTHOR]

[Objective) The study aims to further elucidate the effects of plant topping measures on rhizosphere microbial community structure and potential functions, and to provide necessary theoretical basis for the optimization of topping technology. (Method) The impact of tobacco plant topping on rhizosphere bacterial community structure and potential function was investigated using 16S rRNA high-throughput sequencing technology. [Result] Topping induced changes in the content of nitrogen, phosphorus, and potassium in leaves of flue-cured tobacco. Compared to the control, topping significantly increased the potassium content in tobacco leaves, while decreasing the nitrogen and phosphorus contents. The contents of organic matter, total nitrogen, hydrolyzed nitrogen and available potassium in soil increased significantly after topping, while the soil pH value decreased significantly. The contents of total phosphorus, total potassium and available phosphorus in soil did not change significantly before and after topping. Topping increased the relative abundance of Gemmatimonadetes and Acidobacteria, while decreasing the relative abundance of Proteobacteria, Actinobacteria, Sphingomonas, Gemmatimonas, and Lysobacter. α-diversity and NMDS analysis revealed that topping altered the uniformity and richness of the soil bacterial community, changing its structure significantly. Topping notably increased the Sob index and Chaol index, causing significant separation of the community structure. Redundancy analysis (RDA) and variance decomposition analysis (VPA) indicated that soil nutrient change was a crucial factor in rhizosphere microbial community alteration. Soil physical and chemical properties were closely correlated with microbial community changes, with soil total nitrogen and hydrolyzed nitrogen exerting the greatest influence on microbial communities. LEfSe analysis demonstrated that topping resulted in a significant increase in bacterial diversity. Functional prediction indicated that topping led to a decrease in the relative abundance of soil chemoheterotrophic and oxidoheterotrophic bacteria. [Conclusion] Topping induces significant alterations in the structure and potential functions of the rhizosphere microbial community. The changes in rhizosphere soil nutrients caused by topping may constitute a key factor influencing the variations observed in the rhizosphere bacterial community. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)