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This document, titled "Recommendations for plant growth-promoting bacteria inoculation studies," discusses common mistakes and flaws in the methodology of studies on plant growth-promoting bacteria (PGPB) inoculation. The authors highlight issues such as inaccurate methods for measuring plant effects, incorrect techniques for determining the ability to solubilize inorganic phosphate, and deficiencies in the design of PGPB consortia. The document also addresses flaws in assessing the production of the phytohormone indoleacetic acid (IAA), conducting experiments in greenhouses and field conditions, monitoring root colonization and persistence of inoculated bacteria, and selecting appropriate controls. Despite these inconsistencies, the authors emphasize the potential of microbial soil inoculation for reducing the use of fertilizers and pesticides and promoting soil sustainability in agriculture. They call for future research to address these issues and provide valuable insights into the preparation of commercial products used in agriculture. [Extracted from the article]

This article discusses the role of soil microorganisms in the dynamics of soil organic matter (SOM) and how it is affected by land use and climate change. The authors highlight recent research that has shifted the understanding of SOM dynamics, emphasizing the importance of microbially derived SOM, microbial necromass, and root biomass and exudates. The article also presents five papers that investigate microbial control of SOM dynamics under different land uses and management practices. The findings suggest that microbial carbon use efficiency (CUE) is a key factor in balancing SOC accumulation and loss. The article concludes by emphasizing the need for a deeper understanding of microbial control of SOM dynamics in order to develop effective strategies for climate change adaptation and mitigation. [Extracted from the article]

Drylands are arid and semi-arid areas whose main feature is their low level of precipitation. They cover nearly half of Earth's land surface and are distributed worldwide, constituting the planet's largest biome. Dryland soils have low fertility, are greatly affected by climate variability, and are vulnerable to wind and water erosion. The phosphorus-rich soil dust traveling by aeolian processes from drylands is the main source of P for the global primary productivity in P-limited areas, a fact that highlights the importance of arid and semiarid areas in the global nutrient budget. This review discusses the development of dryland soils, the sources of P in drylands, the C, N, P, relation in dryland soils, the fractionation and bioavailability of P, and biotic and abiotic factors affecting the P in drylands. Finally, the dynamic of P in biological soil crusts and resource islands is discussed. Combined, they contribute to the surface organic matter pools, alter the soil fertility, and are determinant factors in P's availability in dryland soils. We conclude the review by highlighting the gaps in knowledge that should be addressed in future research regarding biological and abiotic processes that determine the dynamics of P in drylands. [ABSTRACT FROM AUTHOR]

Plant–microbial competition for N in the rhizosphere affects net primary production and N cycling, and depends on plant physiological factors, including photosynthesis and transpiration. Here, we studied the diurnal competition for N between plants and microorganisms and quantified plant C allocation by maize (Zea mays) and wheat (Triticum aestivum) in a nutrient-poor soil. In situ concurrent pulse 15NO3− and 13CO2 labeling was carried out to trace the N uptake from the soil and C allocation to plant–microorganisms–soil system in the first 12 and 24 h after labeling, corresponding to daytime and nighttime. Plants outcompeted microorganisms for NO3− uptake from the rhizosphere during daytime and nighttime. Diurnal dynamics had a low effect on microbial NO3− uptake, which varied between 7 and 15% of added N for maize and between 3 and 6% of added N for wheat after the first 12 and 24 hours. NO3− uptake by maize was not affected by diurnal dynamics, but NO3− uptake by wheat was higher during daytime than that during nighttime. The 13C allocation to plants and microorganisms was similar between daytime and nighttime. N utilization was closely related to photosynthate partitioning in plant shoots and roots, indicating coupling between C allocation and N utilization. These findings indicate that plants grown in nutrient-poor soils (as used in this study) dominate over microorganisms for N uptake and release newly photosynthesized C for rhizosphere microorganisms. The diurnal dynamics of these plant–microbial interactions are plant species–specific: important for wheat but irrelevant for maize. [ABSTRACT FROM AUTHOR]

Springer, Singapore, pp 457-495 10 Lan T, Li M, He X, Deng O, Zhou W, Luo L, Chen G, Yuan S, Ling J, Zeng M, Gao X. Effects of synthetic nitrification inhibitor (3,4-dimethylpyrazole phosphate; DMPP) and biological nitrification inhibitor (methyl 3- (4-hydroxyphenyl) propionate; MHPP) on the gross N nitrification rate and ammonia oxidizers in two contrasting soils. As mentioned above, DNA-based approaches are coupled with measurements of potential nitrification activity (PNA) or net nitrification, also known as potential nitrification rate (PNR), and net nitrification rate. These aspects cannot be ignored by BNI researchers, as BNI implies the reduction of gross nitrification rate. However, neither PNA nor net nitrification rates provide information about the I in situ i nitrifying activity, which can be reflected by the gross nitrification rate (i.e. production of NO SB 3 sb SP - sp ) using SP 15 sp N isotope techniques (see below). [Extracted from the article]

We studied the viable but nonculturable (VBNC) state of the human pathogen Escherichia coli O157:H7 during desiccation using genomic, proteomic, and direct methods in a model soil under controlled conditions. During desiccation, the bacterial cells reduced their culturability, protein synthesis, and DNA replication, and changed their morphology. Four days after rewetting of dry soil, the culturability of E. coli recovered, and protein synthesis was restored. A total of 2,324 proteins were differently expressed in the VBNC state compared to the culturable state and identified. Morphological changes during the VBNC state paralleled the downregulation of cytoskeletal proteins and enzymes of the tricarboxylic acid cycle. On the contrary, proteins involved in nutrient transport, membrane, chemotactic, flagellar, virulence, and adhesion were upregulated. Overall, our results indicated that low soil moisture can induce the VBNC state in E. coli O157:H7 but this state can revert to culturability and full metabolic activity upon soil rewetting. These findings can be important aspects in assessing the environmental risks posed by microbial pathogens in soil. [ABSTRACT FROM AUTHOR]

In contrast to what is observed in aerobic uplands, microbial biomass and the presence of electron acceptors, such as iron oxides, play a crucial role in regulating soil organic C (SOC) mineralisation in paddy soils. However, the related underlying mechanisms are still poorly explored. We conducted an anaerobic incubation study to investigate changes in CO2 emissions from SOC and acetate (13C-labeleld) in response to iron oxide (ferrihydrite and goethite) addition in chloroform-fumigated and unfumigated paddy soils. The iron oxides, as electron acceptors, increased CO2 emissions from SOC with stronger impact under ferrihydrite than goethite addition. However, the acetate addition, as a preferable C source for reducing microbes, decreased SOC mineralisation and caused a negative priming effect. CO2 emission from both acetate and SOC was affected by microbial biomass change. In the acetate-treated soil, goethite in the fumigated soil (i.e. high microbial biomass) increased CO2 emissions from acetate, providing electron acceptors, and decreased CO2 emissions from SOC. Ferrihydrite accepted electrons and adsorbed acetate, resulting in a slight decline in CO2 emission from acetate. However, in the fumigated soil (i.e. low microbial biomass), both iron oxide additions reduced CO2 emissions from acetate and SOC and likely the dominant role of both iron oxides shifted from being electron acceptors to being adsorbents, thus limiting acetate accessibility to microorganisms. The results suggest that microbial biomass is a key driver in shifting the effects of iron oxides on organic C mineralisation in anaerobic paddy soils. [ABSTRACT FROM AUTHOR]

However, in 1998, Professor Bashan proposed two new terms for general scientific use that would seem to encompass all the plant beneficial bacteria: "biocontrol plant growth-promoting bacteria" (Biocontrol-PGPB) and "plant growth-promoting bacteria" (PGPB) (Bashan and Holguin [4]). In 1986, Professor Bashan developed an alginate-based encapsulated inoculants of I Azospirillum brasilense i (Bashan [2]); that was the start point of the use of synthetic inoculants as an alternative to the delivery of PGPB in the field. Work on plant-microorganisms interaction of arid ecosystems Prof. Bashan contributed significatively to the knowledge of the interactions between microorganisms and plants in the desert. 10.1007/s00203-011-0695-8 21 Lopez BR, Tinoco-Ojanguren C, Bacilio M, Mendoza A, Bashan Y. Endophytic bacteria of the rock-dwelling cactus Mammillaria fraileana affect plant growth and mobilization of elements from rocks. [Extracted from the article]

Using the stable N isotope technique, it is possible to trace N derived from many sources and pools and thus quantify the gross N transformation rates and plant N uptake, and the processes of gaseous N emissions (Choi et al. [2]). Carbon (C) and nitrogen (N) are key elements governing soil productivity and sustainability in terrestrial ecosystems including croplands, forests, and wetlands. The synthesized and experimental data published in the articles of this issue provides novel insights into the use of stable C and N isotopes in the study of C and N dynamics in different land uses under global change. [Extracted from the article]

In this study, we show that composition shifts of ammonia oxidizer communities imposed by a 22-year field fertilization regime could be well retained in both fresh and air-dried soils. The abundance and composition of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were measured in fresh soils, which received no fertilization (CK), chemical fertilization (NPK), and chemical plus organic matter fertilization (NPK/OM) for 22 years. The air-drying treatment of fresh soil was also conducted for pairwise analysis. We found that in fresh soils DGGE fingerprints of AOB showed significant changes under both NPK and NPK/OM treatments when compared with control (CK) and that microbial shift was almost identical in air-dried soils. Long-term nutrient fertilization did not affect AOA communities in either air-dried or fresh soils. Compared to CK treatment, real-time PCR indicated that AOB amoA genes increased significantly in fresh soils of NPK (59-fold) and NPK/OM (48-fold) plots and in air-dried NPK and NPK/OM soils by 22-fold and 19-fold respectively. Our results demonstrate that community shifts of AOB in fresh soils under chronic N fertilization could be well preserved in air-dried soils, despite the apparent decline in absolute abundance of ammonia oxidizers. These results suggest that air-dried soil could be a useful resource for deciphering the adaptive strategy of ammonia oxidizers under N enrichment when the significant changes of community composition occurred in fresh soils. [ABSTRACT FROM AUTHOR]

Aims: Study of the microbial expression profile in the rhizosphere of two contrasting maize lines, differing in the Nitrogen Use efficiency (NUE).Methods: The Lo5 and T250 inbred maize characterized by high and low NUE, respectively, were grown in rhizoboxes allowing precise sampling of rhizosphere and bulk soils. We conducted metatranscriptomic of rhizosphere and bulk soil by m-RNA sequencing.Results: High activity of bacteria was observed compared to archaea and fungi in both rhizosphere and bulk soils of both maize lines. Proteobacteria and Actinobacteria were involved in all processes, while significant shifts occurred in the expression of Bacteroidetes, Chloroflexi, Firmicutes, Acidobacteria, Cyanobacteria, archaea and fungi, indicating their possible role in specific processes occurring in rhizosphere of two maize lines. Maize plants with different NUE induced changes in microbial processes, especially in N cycling, with high NUE maize favouring ammonification and nitrification processes and low NUE maize inducing expression of genes encoding for denitrifying process, likely favoured by longer N residence time in the rhizosphere.Conclusions: Overall our results showed that maize lines with different NUE shaped not only microbial communities but also conditioned the microbial functions and the N cycle in their rhizosphere. While the plant NUE is genetically determined and an inherent plant physiological trait, it also stimulates changes in the microbial community composition and gene expression in the rhizosphere, favouring microbial processes that mineralize and oxidize N in the high NUE maize. These results can improve our understanding on plant-microbe interaction in the rhizosphere of crop plants with potential applications for improving the management practices of the agro-ecosystems. [ABSTRACT FROM AUTHOR]

While root exudation follows diurnal rhythms, little is known about the consequences for the microbiome of the rhizosphere. In this study, we used a metatranscriptomic approach to analyze the active microbial communities, before and after sunrise, in the rhizosphere of barley. We detected increased activities of many prokaryotic microbial taxa and functions at the pre-dawn stage, compared to post-dawn. Actinomycetales, Planctomycetales, Rhizobiales, and Burkholderiales were the most abundant and therefore the most active orders in the barley rhizosphere. The latter two, as well as Xanthomonadales, Sphingomonadales, and Caulobacterales showed a significantly higher abundance in pre-dawn samples compared to post-dawn samples. These changes in taxonomy coincide with functional changes as genes involved in both carbohydrate and amino acid metabolism were more abundant in pre-dawn samples compared to post-dawn samples. This study significantly enhances our present knowledge on how rhizospheric microbiota perceives and responds to changes in the soil during dark and light periods. [ABSTRACT FROM AUTHOR]

Enzyme activity as a method for soil biochemistry and microbiology research has a long history of more than 100 years that is not widely acknowledged in terms of adherence to strict assay protocols and the interpretation of results. However, in the recent past, there is a growing lack of recognition of the historic advancements among researchers that use soil enzymology. Today, many papers are being published that use methods that either do not follow exact protocols as originally vetted in the research literature or individual labs use their own method that has not been optimized for pH, co-factors, substrate concentrations, or other conditions. This is of particular concern for fluorogenic substrates and microplate methods. Furthermore, there is a lack of understanding of the origin and location of a given enzyme being studied. Notably, regardless of the enzyme, it is too often assumed that enzyme activity equals microbial activity-which is not the case for most hydrolytic enzyme assays. Because as established by Douglas McLaren in the 1950s, a considerable amount of activity can come from catalytic enzymes stabilized in the soil matrix but that are no longer associated with viable cells (known as abiontic enzymes). In summary, today, many papers are using imperfect methods and/or misinterpret enzyme activity data that at a minimum confounds cross paper studies and meta-analysis. However, most importantly, lack of historical perspectives and ignoring strict protocols cause redundancy and fundamentally undermine the discipline and understanding of soil microbiology/biochemistry when enzymology methods are used. [ABSTRACT FROM AUTHOR]

The living soil is instrumental to key life support functions (LSF) that safeguard life on Earth. The soil microbiome has a main role as a driver of these LSF. Current global developments, like anthropogenic threats to soil (e.g., via intensive agriculture) and climate change, pose a burden on soil functioning. Therefore, it is important to dispose of robust indicators that report on the nature of deleterious changes and thus soil quality. There has been a long debate on the best selection of biological indicators (bioindicators) that report on soil quality. Such indicators should ideally describe organisms with key functions in the system, or with key regulatory/connecting roles (so-called keystone species). However, in the light of the huge functional redundancy in most soil microbiomes, finding specific keystone markers is not a trivial task. The current rapid development of molecular (DNA-based) methods that facilitate deciphering microbiomes with respect to key functions will enable the development of improved criteria by which molecular information can be tuned to yield molecular markers of soil LSF. This review critically examines the current state-of-the-art in molecular marker development and recommends avenues to come to improved future marker systems. [ABSTRACT FROM AUTHOR]

Aim: The rate of nitrate (NO3−) uptake and changes in rhizosphere properties were studied growing seedlings of two maize inbred lines differing in nitrogen use efficiency (NUE) in rhizoboxes.Results: Changes in NO3− uptake rates occurred in response to anion addition (induction) in seedlings grown both in hydroponic culture and in soil in rhizoboxes. The characterization of root exudate composition showed a line-specific metabolite profile, which was also affected by NO3− availability. The induction affected respiration, nitrification, ammonification and enzyme activities of the rhizosphere. Furthermore, the composition of rhizosphere bacterial communities of the two maize lines differed suggesting the selective capacity of plants.Conclusions: Overall, results showed a strong and fast modification of rhizospheric soil properties in response to physiological changes in plants caused by fluctuating NO3− availability. [ABSTRACT FROM AUTHOR]

Alkaline phosphomonoesterase (ALP) mainly originates from soil microbial secretion and plays a crucial role in the turnover of soil phosphorus (P). To examine the response of ALP-encoding microbial communities (analysed for the biomarker of the ALP gene, phoD) of soils and derivative soil fractions to different fertilisation regimes, soil samples were collected from a long-term experimental field (over 35 years). The different organic P (Po) pools of soil fractions and the ALP activity of soil were also determined. Compared with chemical-only fertilised soils, the ALP activity was 232-815% higher in organic-amended soils, and the highest enzyme activity was observed in the organic-only fertilised treatment. The abundance of the phoD gene harbouring in soil fractions, determined by quantitative PCR (qPCR), was affected by different fertilisations. The highest abundance of the phoD gene was generally detected in the 2-63-μm-sized fraction (silt), but most phoD-encoding microbial species were associated to the 0.1-2-μm-sized fraction (clay) in the chemical-only fertilised soil. The contents of labile Po (LPo), moderately labile Po (MLPo) and fulvic acid-associated Po (FAPo) were significantly correlated with the phoD gene abundance, whereas only LPo content was significantly correlated with the ALP activity. The dominant phoD-encoding phylas were Actinobacteria and Proteobacteria, according to a high-throughput sequencing. Bradyrhizobium, a N-fixer identified as a phoD-encoding genus, showed the highest abundance in fertilised soils. The abundance of Bradyrhizobium, Streptomyces, Modestobacter, Lysobacter, Frankia and Burkholderia increased with the organic-only amendment and was significantly correlated with the ALP activity. According to structure equation models (SEM), pH and LPo content significantly and directly affected the ALP activity; the soil organic C (C) content was related to composition and abundances of phoD-harbouring microbial communities; since both microbial properties were correlated to the ALP activity, the C content was indirectly related to the ALP activity. In conclusion, soil management practices can be used to optimise the contents of soil available P and the organic P with regulation of soil ALP activity and the community composition of corresponding microbes. [ABSTRACT FROM AUTHOR]

Industrial production of synthetic nitrogen fertilizers (starting in the 1930s) and their large-scale infusion into agriculture (during the 1960s) have transformed global food production but brought major ecological and environmental problems. Nitrogen fertilizer use has grown 20-fold since the 60 s to reach present levels of 150 Tg y SP -1 sp and is expected to reach 300 Tg y SP -1 sp by 2050 (to double food production from present levels), clearly in an unsustainable path. The Green Revolution, starting from the early 1960s, intensified the application of industrially produced N fertilizers in farming, led to food security for billions of people and transformed human society in the twenty-first century. [Extracted from the article]

We studied the molecular diversity of β-glucosidase-encoding genes, microbial biomass, cellulase, N-acetyl-glucosaminidase, β-glucosidase, and β-galactosidase activities in the rhizosphere and bulk soil of two maize lines differing in nitrogen use efficiency (NUE). The maize lines had significant differences in diversity of β-glucosidase-encoding genes in their rhizosphere, and Actinobacteria and Proteobacteria were the dominating phyla in all samples, but representatives of Bacteroidetes, Chloroflexi, Deinococcus- Thermus, Firmicutes, and Cyanobacteria were also detected. Among the Proteobacteria, β-glucosidase genes from α-, β-, and γ-Proteobacteria were dominant in the rhizosphere of the high NUE maize line, whereas δ- Proteobacteria β-glucosidase genes were dominant in the rhizosphere of the low NUE maize line. The high NUE maize line also showed higher glucosidase activities in the rhizosphere than the low NUE maize line. We concluded that plants with high NUE select bacterial communities in the rhizosphere differing in the diversity of β-glucosidase-encoding genes which likely result in higher C-hydrolyzing enzyme activities. These effects on the diversity of β-glucosidase-encoding genes may influence the C dynamics in the agro-ecosystems. [ABSTRACT FROM AUTHOR]

Purpose: Many decades of research have shown that humic compounds as part of the soil organic matter (SOM) are essential for the stability and ecosystem services of soils. James P. Martin and Konrad Haider based on several pioneers in humus research improved the basis for the current knowledge of key processes in the soil environment, in particular structure and formation of humus triggered mainly by soil fungi. Other major contributions are briefly described but not in the focus of this article, such as their innovative tracer experiments with isotope-labelled xenobiotic chemicals and natural litter to study their fate. Both scientists inspired generations of younger researchers to advance their approaches and laid the cornerstone of the current understanding of soil organic matter formation. Results and discussion: This article values the key experiments of Martin and Haider in this field and the related follow-up research finally resulting in the current view on formation mechanisms of SOM and non-extractable residues (NER) of xenobiotics. The improved understanding of these processes considering necromass with tissue residues of plants, microbes and animals challenges the traditional views of humic matter as macromolecular organic matrix, which according to the research of the last years represents only a variable part of the total organic matter besides associates of low molecular weight molecules. We discuss views on soil organic matter and humic substances that are nowadays considered not to differ in molecular diversity. We will start by demonstrating the understanding of humus characteristics and humus formation three decades ago closely related to the findings of Martin and Haider. Methodological approaches to characterize relevant structural and mechanistic pictures of SOM such as the priming effect, clay mineral catalysed reactions and the various mechanisms by which natural and xenobiotic chemicals are protected in soil are briefly illustrated by examples. Fungal activities in producing secondary metabolites like polyketides and their probably minor contributions to SOM formation are presented. Conclusions and perspectives: Open research questions stimulated by these two soil scientists are sketched which are nowadays possible to address by new sophisticated high-resolution techniques. [ABSTRACT FROM AUTHOR]

We performed a longitudinal study (repeated observations of the same sample over time) to investigate both the composition and structure of temporal changes of bacterial community composition in soil mesocosms, subjected to three different treatments (water and 5 or 25 mg kg of dried soil Cd). By analogy with the pan genome concept, we identified a core bacteriome and an accessory bacteriome. Resident taxa were assigned to the core bacteriome, while occasional taxa were assigned to the accessory bacteriome. Core and accessory bacteriome represented roughly 35 and 50 % of the taxa detected, respectively, and were characterized by different taxonomic signatures from phylum to genus level while 15 % of the taxa were found to be unique to a particular sample. In particular, the core bacteriome was characterized by higher abundance of members of Planctomycetes, Actinobacteria, Verrucomicrobia and Acidobacteria, while the accessory bacteriome included more members of Firmicutes, Clamydiae and Proteobacteria, suggesting potentially different responses to environmental changes of members from these phyla. We conclude that the pan-bacteriome model may be a useful approach to gain insight for modeling bacterial community structure and inferring different abilities of bacteria taxa. [ABSTRACT FROM AUTHOR]

The influence of exposure to engineered nanoparticles (NPs) was studied in tomato plants, grown in a soil and peat mixture and irrigated with metal oxides (CeO, FeO, SnO, TiO) and metallic (Ag, Co, Ni) NPs. The morphological parameters of the tomato organs, the amount of component metals taken up by the tomato plants from NPs added to the soil and the nutrient content in different tomato organs were also investigated. The fate, transport and possible toxicity of different NPs and nutrients in tomato tissues from soils were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The tomato yield depended on the NPs: FeO-NPs promoted the root growth, while SnO-NP exposure reduced it (i.e. +152.6 and −63.1 % of dry matter, respectively). The NP component metal mainly accumulated in the tomato roots; however, plants treated with Ag-, Co- and Ni-NPs showed higher concentration of these elements in both above-ground and below-ground organs with respect to the untreated plants, in addition Ag-NPs also contaminated the fruits. Moreover, an imbalance of K translocation was detected in some plants exposed to Ag-, Co- and FeO-NPs. The component metal concentration of soil rhizosphere polluted with NPs significantly increased compared to controls, and NPs were detected in the tissues of the tomato roots using electron microscopy (ESEM-EDS). [ABSTRACT FROM AUTHOR]

Soil is considered as one of the most biodiverse environments on Earth; yet, the taxonomy, occurrence, and role of its different microbial populations are largely unknown. Here, two sterilized soils (from England and Italy) were inoculated with a subsample of their initial microbial communities and/or those from the other soil to study their microbial community evolution. This approach compared two driving factors (original community and soil physico-chemical characteristics) for microbial community definition. After 2 months of incubation and based on metagenomic datasets, the two inoculated communities (from an English grassland and an Italian forest) possessed similar functional and taxonomical structures when inoculated in the same sterile soil. For example, the newly colonized Italian soil was dominated by Actinobacteria related organisms (>66 % of the detected community) with a functional distribution independent of the inoculated soil origin. In addition, some of the organisms that dominated the different inoculated communities after 2 months were similar for a given sterile soil whether they came from the English grassland or the Italian forest, and they had not been detected in the original microbial community from either soil. Thus, similar microorganisms with low representation from the two distinct communities emerged in each sterilized soil, thus increasing the microbial diversity recovered from the microbial community of the donor soil. So far, these observations support the idea that different temperate soil microbial communities have different evenness due to environmental physico-chemical variations, yet have similar community composition (richness), and thus develop similarly when colonizing the same habitat. [ABSTRACT FROM AUTHOR]

Soil proteomics is facing problems such as low yields of protein extraction from soil and low protein identification rates as compared to theoretical estimates of soil proteome. This work aimed to evaluate the effect of soil-borne humic substances (HS) on the identification of model proteins with different properties, such as myoglobin (Mb), α-glucosidase (αG), and β-glucosidase (βG), by using electrophoretic and ESI- and MALDI-mass spectrometry (MS) methodologies. Results showed that the contact between proteins and HS did not alter protein electrophoretic mobility but led to protein modifications that affected protein identification by MS. The decrease in protein identification parameters was more evident for Mb than for αG and βG, probably due to its lower molecular weight and less complex molecular structure. Analysis of MS data indicated that hydrophobic interactions could be responsible for the observed effects of contact between proteins and HS. [ABSTRACT FROM AUTHOR]

Cupriavidus metallidurans CH34 is a completely sequenced soil-borne beta-proteobacterium with known genome and proteome. Comparative 2-D electrophoresis and protein mass spectrometry were used to compare the proteome of C. metallidurans CH34 from liquid culture and after incubation for 1, 3, and 12 days in microcosms containing quartz sand, kaolinite, montmorillonite, or an artificial soil. Results showed that proteome from liquid culture was similar to CH34 proteins extracted from sand and kaolinite, whereas the proteins extracted from artificial soil differed significantly and no proteins were detected from C. metallidurans CH34 incubated in the montmorillonite microcosms. Protein recovery decreased on prolonging incubation time in all microcosms. Mass spectrometry identification showed that the trend of lower recovery upon incubation time was independent on the putative function of protein. These results suggest that the soil solid phase influences the protein recovery and soil proteomic analysis and that distinction between protein recovery and protein expression in soil will be a challenging for soil proteomic researchers. [ABSTRACT FROM AUTHOR]

Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily-and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming. [ABSTRACT FROM AUTHOR]

Glucose (C), glucose plus NO3 – (C+N) or glucose plus NO3 – plus PO4 3– (C+N+P) were added to an arable and a forest soil at a single dose, or split into four equal doses over 4 consecutive days, and the response of several enzyme activities, ATP content and respiration rate were monitored for 11 days. ß-Glucosidase activity was reduced in the two soils during the first day by substrate addition. Thereafter, this enzyme activity varied only slightly in the arable soil with reference to the non-amended control, while it increased substantially in the beech forest when C+N and C+N+P were added. Casein-hydrolysing activity increased in the C treatment and decreased after C+N+P addition during the first 4 days in the two soils. After 11 days, protease activity was enhanced in the arable soil when C+N was applied in a split dose. Urease activity decreased during the first 4 h, particularly in the arable soil with the addition of C+N or C+N+P, applied in a single dose, and then continuously increased. Thus, urease responded to high nutrient availability, being firstly repressed or inhibited, and stimulated afterwards. Phosphatase activity was only slightly modified in the arable soil but substantially increased in the beech forest by C+N addition. The presence of P usually decreased phosphatase activity. Arylsulphatase activity was repressed after substrate addition, which was particularly evident in the arable soil. In the beech forest topsoil, C added alone increased this enzyme activity. Significant correlations between ATP content and enzyme activity were only observed for urease in the arable system treated with C+N and in the forest when C was applied in a split dose. The effect of C, C+N and C+N+P addition varied between the arable and the forest soil according to environmental conditions and microbial ecophysiology. [ABSTRACT FROM AUTHOR]

In the 25-year-old vineyard of a farm near the Maremma National Park (Central Italy), replicate plots were established with a mulch of Trifolium subterraneum L. or cultivation and two levels of fertilizer. The mai objective of this research was to analyse responses by soil invertebrates and nutrients after introducing a herbaceous component into the system; the yield was also considered. The greater availability of organic substrate and the reduced cultivation as a result of green mulching increased the soil mesofauna biomass, especially detritivores. With time, a significant difference became evident between the populations of invertebrates present in the mulched plots and those in the cultivated plots. Over 2 years, most nutrients (Ca, K, P, and N) were significantly increased in the mulched plots compared to the cultivated plots. Grape yields were consistently higher in the bare plots. No significant differences were found in fertilizer effects. [ABSTRACT FROM AUTHOR]

The article focuses on a study regarding the need of identifying microorganisms, constituents, and application methods for microbe-based or pesticide-based products. It mentions the use of biological control agents, pesticides and plant growth-promoting microorganisms to enhance plant productivity. It also mentions that pesticides have toxicological properties to control pest organism.

An obituary for soil chemist Jean-Claude Fardeau is presented.