Soil Microbiota Research Articles

Agronomic Efficiency of Compost Extracts and Nitrogen-Fixing Bacteria in Soybean Crops

Regenerative agriculture and the use of bioinputs have been gaining prominence in the global agribusiness sector, driven by the growing demand for healthier foods produced with minimal impact on ecosystems. In this context, compost and its derivatives (compost extracts and teas) are used to provide effective microorganisms to crops, although production processes affect the efficiency of compost extracts, as well as the soil microbiota. Thus, the hypothesis raised was that the organic matter source used for compost formation affects the agronomic efficiency of compost extracts. The objective of this study was to evaluate the effect of compost extracts based on litterfall of angiosperm (AC) and gymnosperm (GC) species, and the use of inoculation with the nitrogen-fixing bacteria Bradyrhizobium japonicum and Azospirillum brasilense (Bra+Azo), on soil quality, crop growth, grain yield, and disease control in soybean (Glycine max L.) crops. Using AC and GC resulted in varying effects on soybean growth and soil microbial biomass carbon (SMBC), confirming the hypothesis that the organic matter source affects the agronomic efficiency of compost extracts. Plants inoculated with Bra+Azo exhibited higher chlorophyll contents, resulting in a higher photochemical yield than for those treated with compost extracts (AC and GC). However, plants inoculated with AC and GC exhibited high plasticity in mitigating photochemical stress, reaching similar photosynthetic and transpiration rates to those observed in plants inoculated with Bra+Azo. Additionally, inoculation with Bra+Azo, overall, improved the photosynthetic efficiency of soybean plants, and the compost extracts (AC and GC) were more effective than the inoculation with Bra+Azo in increasing soybean 1000-grain weight, probably due to improvements in root development. The growth promotion observed with AC and GC is likely attributed to increases in SMBC by these compounds, denoting improvements in soil quality and biocontrol of damage caused by insect attacks.

Impact of gaseous smoke pollutants from modelled fires on air and soil quality

Forest fires produce large volumes of pollutants in the atmospheric air. Fires contribute significantly to greenhouse gas emissions worldwide apart from industrial and traffic pollutants. The study reports the results of research on the effect of gaseous substances from burning forest combustibles on air quality and deposition of emissions on soil. It was determined a significant excess in smoke of such substances as carbon monoxide (3570 mg/m3), nitrogen oxide and dioxide (40 mg/m3 and 60 mg/m3) saturated hydrocarbons – methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane nonadecane. The obtained results evidence the increased concentrations of pollutants, including climate-active substances in the air. They can affect negatively both the climate and ecological state of soils. A negative effect of gaseous products of combustion on soil (Haplic Chernozem) by deposition was determined, which caused changes in soil properties. It was reliably established that the enzymatic activity of soil (Haplic Chernozem) significantly decreased under the influence from smoke of fire during 60 min. Catalase appeared to be the most sensitive indicator. The catalase activity decreased by 25% compared to control values. Peroxidase activity decreased by 15%, urease by 20% and phosphatase by 16%. The pH changed from 7.8 to 6.3 after exposure of the soil to smoke. Soil microbiota was also adversely affected by smoke. High sensitivity was recorded for microscopic fungi. Their abundances decreased by 26%–87% after 10–60 min of smoke exposure. Bacteria were found to be more resistant to toxic smoke (28%–33% decrease in abundance). Therefore, smoke from fires can be considered as one of the factors that can affect soil.Graphical

The Genomic and Phenotypic Characterization of the Sym2A Introgression Line A33.18 of Pea (Pisum sativum L.) with the Increased Specificity of Root Nodule Symbiosis

In pea (Pisum sativum L.), alleles of the Sym2 gene determine the specificity of the interaction with nodule bacteria (rhizobia). The Sym2A allele present in landraces from Afghanistan provides higher selectiveness toward rhizobia than the Sym2E allele present in European cultivars. Rhizobial strains possessing the nodX gene can interact with both Sym2A and Sym2E peas, while strains lacking nodX can interact only with Sym2E peas. Here, we studied the previously obtained introgression line A33.18 bearing Sym2A in a homozygous state in the genome of the European pea cultivar ‘Rondo’. A33.18 has proved its high selectiveness in pot experiments. Genome sequencing has shown that A33.18 possesses an 18.2 Mb region inherited from Afghanistan pea with 63 genes, including 5 receptor kinase genes, among which was the Sym2 candidate gene LykX. In a field experiment, under inoculation with the nodX+ strain TOM, over 95% of nodules of A33.18 contained TOM, as opposed to less than 8% of nodules containing TOM in the parental European cultivar ‘Rondo’. Thus, introgression of Sym2A enabled peas to interact specifically with the nodX+ strain, favoring the formation of nodules by the strain from the inoculum and protecting peas from the indigenous soil microbiota.

Скринінг штамів бактерій родів Bacillus і Pseudomonas, активних проти фітопатогенів роду Fusarium

The using of biological preparations based on bacteria of the genera Bacillus and Pseudomonas is one of the most promising directions in the fight against pathogens of plant diseases. Quite a lot of preparations based on these microorganisms are known, but in some cases their application is characterized by insufficient activity against pathogens, as well as a reduction of the number of saprophytic soil microbiota, which negatively affects the phytosanitary state of the soil and reduces plants’ productivity. The aim of the work was to study the antagonistic activity of individual representatives of the genera Bacillus and Pseudomonas from different biotopes against phytopathogenic Fusarium isolates from affected winter wheat grown in the Odesa region. The largest number of Bacillus and Pseudomonas strains was isolated from the rhizosphere zone of plants. Screening of antagonistically active bacteria showed that this property was inherent in 92.4 % of Bacillus strains and 73.5 % – Pseudomonas strains. Bacillus spp. R14, R31 and S19 inhibited the growth of all selected fusaria (growth inhibition zones exceeded 20 mm). Pseudomonas spp. WR5 and WR7 also showed an antimycotic effect, but the sizes of the growth inhibition zones were less than 20 mm. Pre-cultivation of antagonistically active bacteria of the genera Bacillus and Pseudomonas on organic nutrient media contributed to a better manifestation of antimycotic activity of methanolic extracts of secondary metabolites of the studied strains. The determination of the minimum inhibitory concentrations (MIC) of the extracted metabolites against the selected Fusarium strains showed that the values ​​were variable, ranging from 1 mg/ml to 4 mg/ml depending on the specific strain-antagonist and the pathogen. To determine the spectrum and profile of secondary metabolites of antagonistically active Bacillus spp. R14, S19 and Pseudomonas sp. WR5 strains requires more extensive studies, including high-resolution mass spectrometry, as well as full sequencing and annotation of the genomes of these bacterial strains for their exact identification and detection of secondary metabolite clusters.

Root cap border cells as regulators of rhizosphere microbiota

A rhizosphere (a narrow area of soil around plant roots) is an ecological niche, within which beneficial microorganisms and pathogens compete with each other for organic carbon compounds and for the opportunity to colonize roots. The roots secrete rhizodeposits into the rhizosphere, which include border cells, products of root cell death and liquids secreted by living cells (root exudates). Border cells, which have their name due to their location in the soil next to the root (at the border of the root and soil), represent terminal differentiation of columella and adjacent lateral root cap cells. Border cells can detach from the root cap surface both as single cells and as cell layers. Border cells are constantly supplied to the soil throughout plant life, and the type and intensity of border cells’ sloughing depend on both plant species and soil conditions. Currently, data on the factors that control the type of border cells’ release and its regulation have been described in different plant species. Border cells are specialized for interaction with the environment, in particular, they are a living barrier between soil microbiota and roots. After separation of border cells from the root tip, transcription of primary metabolism genes decreases, whereas transcription of secondary metabolism genes as well as the synthesis and secretion of mucilage containing these metabolites along with extracellular DNA, proteoglycans and other substances increase. The mucilage that the border cells are embedded in serves both to attract microorganisms promoting plant growth and to protect plants from pathogens. In this review, we describe interactions of border cells with various types of microorganisms and demonstrate their importance for plant growth and disease resistance.

Foliar application of nano biochar solution elevates tomato productivity by counteracting the effect of salt stress insights into morphological physiological and biochemical indices

Nano-biochar considers a versatile and valuable sorbent to enhance plant productivity by improving soil environment and emerged as a novel solution for environmental remediation and sustainable agriculture in modern era. In this study, roles of foliar applied nanobiochar colloidal solution (NBS) on salt stressed tomato plants were investigated. For this purpose, NBS was applied (0%, 1% 3% and 5%) on two groups of plants (control 0 mM and salt stress 60 mM). Tween-20 was used as a surfactant to prolong NBS effective stay on plant leaf surface. The results showed that 3% NBS application effectively improved the plant height, plant biomass, fruit count and fruit weight under non-stressed and stressed plants. In addition, 3% NBS application further increased the plant pigments such as chlorophyll by 72% and 53%, carotenoids by 64% and 40%, leaf relative water content by 4.1 fold and 1.07 fold under both conditions, respectively. NBS application stabilized the plasma membrane via reducing electrolyte leakage by 30% as well as reduced the lipid peroxidation rates by 46% and 29% under non-stressed and stressed plants, respectively. 3% NBS application also significantly enhanced the plants primary and secondary metabolites, as well as activities of antioxidant enzymes compared to control plants. Overall, NBS foliar application significantly improved all growth and yield indices, pigments, primary and secondary metabolites, leaf water content, antioxidant enzyme activities as well as reduced electrolyte leakage and lipid peroxidation rates in tomato to combat stress conditions. In future, studies on nano biochar interactions with soil microbiota, surface modifications, long-term environmental impacts, reduced methane gas emissions, and biocompatibility could provide insights into optimizing its use in sustainable agriculture.

Chitosan reduces naturally occurring plant pathogenic fungi and increases nematophagous fungus Purpureocillium in soil under field conditions

Chitosan effects on soil properties were analysed both under laboratory conditions by incubation with constant humidity and temperature and under field conditions in two persimmon field plots with conventional and ecological management. Chitosan was applied in solution or as coacervates. Application of chitosan reduced soil pH, conductivity (CE), and cation exchange capacity (CEC) in pots when applied at field capacity. Chitosan did not affect field soil respiration, which is greatly dependent of soil moisture and temperature. Metabarcoding showed that chitosan significantly modifies the fungal genera composition of ecologically managed field soil. On the contrary, chitosan caused no significant differences in bacterial taxa composition of soil under field conditions. Chitosan coacervates increased naturally occurring nematophagous fungus Purpureocillium (ca. 50-fold) in soil with respect to chitosan solution-treated soil and untreated controls. In addition, chitosan reduced the inoculum of plant pathogenic fungi Alternaria and Fusarium (20% and 50%, respectively) in field soil. Soil microbial network analysis for ITS2+V1–V2 regions revealed that the nematophagous fungus Pochonia promoted network clustering into modules. Furthermore, network analysis for ITS2+V3–V4 regions showed that the nematode trapping-fungus Orbilia and bacteria belonging to Acidimicrobiales and Cytophagales significantly contributed to network clustering in field soil. Our results show that chitosan coacervates increased soil nematophagous microbiota and that both nematode egg parasites and trapping fungi help to structure soil microbiota.

How do various strategies for returning residues change microbiota modulation: potential implications for soil health.

Residue incorporation is a crucial aspect of anthropogenic land management practices in agricultural fields. However, the effects of various returning strategies on the soil microbiota, which play an essential vital role in maintaining soil health, remains largely unexplored. In a study conducted, different residue management strategies were implemented, involving the application of chemical fertilizers and residues that had undergone chopping (SD), composting (SC), and pyrolysis (BC) processes, with conventional fertilization serving as the control (CK). Using metagenomic sequencing, the analysis revealed that while all residue returning strategies had minimal effects on the diversity (both α and β) of microbiota, they did significantly alter microbial functional genes related to carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling, as well as the presence of antibiotic resistance genes (ARGs) and pathogens. Specifically, chopped residues were found to enhance microbial genes associated with C, N, P, and S cycling, while composted residues primarily stimulated C and S cycling. Furthermore, all residue treatments resulted in a disruption of relationships among nutrient cycles, with varying degrees of impact observed across the different management strategies, with the sequence of impact being SD < SC < BC. Moreover, the residue additions resulted in the accumulation of ARGs, while only SC caused an increase in certain pathogens. Finally, through analyzing the correlation network among indices that exhibited active responses to residue additions, potential indicators for functional changes in response to residue additions were identified. This study further offered recommendations for future cropland management practices aimed at enhancing soil health through microbiomes.

Variations of microbiota and metabolites in rhizosphere soil of Carmona microphylla at the co-contaminated site with polycyclic aromatic hydrocarbons and heavy metals.

Co-contamination with organic/inorganic compounds is common in industrial area and poses a great risk to local soil ecological environment. In this study, an operating ink factory site co-contaminated with polycyclic aromatic hydrocarbons (PAHs, mild to moderate pollution level) and heavy metals (HMs, heavy pollution level) was selected and screened for native vegetation, Carmona microphylla. High-throughput sequencing and metabolomics were mainly used to investigate the responses of soil bacteria and metabolites to the composite pollution and rhizosphere effect. As the results showed, among three pollution levels, a medium level of pollution was favorable to increase the richness and diversity of soil bacterial community, while high level of pollution greatly decreased special OTUs number. In addition, HMs were the most significant factors driving bacterial community structure, especially for Cd. The influence of medium molecular weight PAHs with 4 rings (MMW-PAHs) on dominant bacteria was greater than low molecular weight PAHs with 2-3 rings (LMW-PAHs) and high molecular weight PAHs with 5-6 rings (HMW-PAHs). Soil bacterial function was affected mainly by pollution level, but not rhizosphere effect, in which high pollution level changed α diversity and structure and composition of C- and N-cycling bacteria. Rhizosphere promoted network complexity by increasing the connection densities among bacterial communities, metabolites, soil properties and the involved number of metabolites. Compared to HMs, PAHs played a more important role in shaping bacterial community through affecting metabolites in non-rhizosphere soil, which was different from rhizosphere soil with a more significant effect of HMs than PAHs. Some key bacterial taxa have established resistance to HMs in rhizosphere soils, whereas they were sensitive to compound contamination in non-rhizosphere soils. Some key bacterial taxa are resistant to HMs in rhizosphere soils, whereas they are susceptible to complex contamination in non-rhizosphere soils, which could be a consequence of the rhizosphere by regulating soil metabolism. It also provides a valuable reference for how co-contaminants and rhizosphere effect shape together soil bacterial community through the changes of soil metabolites.

Is it worth paying attention to actinedid mites in agricultural fields?

Agricultural management increases the seasonal dynamics of soil-dwelling organisms compared to natural habitats. Our knowledge is very poor about the relationship between seasonal changes of soil microorganisms and the microbivorous soil arthropods. To reveal these connections, we have to know more about the seasonal changes of soil-dwelling microarthropods in croplands. Actinedid mites are rarely the subject of synecological studies, however, this group regularly reaches the dominant part of mite assemblages in agro-ecosystems. In this study, we investigated the seasonal density changes of actinedid mites from two independent studies of agricultural fields. Soil samples were taken from maize and wheat fields for two years, and from newly established meadows for one year in summer and autumn in Hungary. Soil-dwelling mites were enumerated and identified at the suborder level and soil parameters were measured. Actinedid mites dominated most of our soil samples. The density of Endeostigmata was the highest in the summer and the density of Heterostigmata was the highest in the autumn within one year among different crop species, soil types, and years. Endeostigmatid mites had negative relationships with soil nitrogen parameters and positive with soil moisture. Heterostigmatid mites had various relationships with soil moisture. The ecology of actinedid mites is under-examined but their high number in agricultural fields may justify the fact that they should receive more attention. We assume that Actinedida, mainly Endeostigmata and Heterostigmata are worth to investigate in croplands as a starting point to reveal the connection between the seasonality of soil mites and soil microbiota.

Growth of microbes in competitive lifestyles promotes increased ARGs in soil microbiota: insights based on genetic traits

BackgroundThe widespread selective pressure of antibiotics in the environment has led to the propagation of antibiotic resistance genes (ARGs). However, the mechanisms by which microbes balance population growth with the enrichment of ARGs remain poorly understood. To address this, we employed microcosm cultivation at different antibiotic (i.e., Oxytetracycline, OTC) stresses across the concentrations from the environmental to the clinical. Paired with shot-gun metagenomics analysis and quantification of bacterial growth, trait-based assessment of soil microbiota was applied to reveal the association between key ARG subtypes, representative bacterial taxa, and functional-gene features that drive the growth of ARGs.ResultsOur results illuminate that resistome variation is closely associated with bacterial growth. A non-monotonic change in ARG abundance and richness was observed over a concentration gradient from none to 10 mg/l. Soil microbiota exposed to intermediate OTC concentrations (i.e., 0.1 and 0.5 mg/l) showed greater increases in the total abundance of ARGs. Community compositionally, the growth of representative taxa, i.e., Pseudomonadaceae was considered to boost the increase of ARGs. It has chromosomally carried kinds of multidrug resistance genes such as mexAB-oprM and mexCD-oprJ could mediate the intrinsic resistance to OTC. Streptomycetaceae has shown a better adaptive ability than other microbes at the clinical OTC concentrations. However, it contributed less to the ARGs growth as it represents a stress-tolerant lifestyle that grows slowly and carries fewer ARGs. In terms of community genetic features, the community aggregated traits analysis further indicates the enhancement in traits of resource acquisition and growth yield is driving the increase of ARGs abundance. Moreover, optimizations in energy production and conversion, alongside a streamlining of bypass metabolic pathways, further boost the growth of ARGs in sub-inhibitory antibiotic conditions.ConclusionThe results of this study suggest that microbes with competitive lifestyles are selected under the stress of environmental sub-inhibitory concentrations of antibiotics and nutrient scarcity. They possess greater substrate utilization capacity and carry more ARGs, due to this they were faster growing and leading to a greater increase in the abundance of ARGs. This study has expanded the application of trait-based assessments in understanding the ecology of ARGs propagation. And the finding illustrated changes in soil resistome are accompanied by the lifestyle switching of the microbiome, which theoretically supports the ARGs control approach based on the principle of species competitive exclusion.4ZqjNsN9dRS1iWJDwru5hLVideo

Data-Driven Approach for Designing Eco-Friendly Heterocyclic Compounds for the Soil Microbiome.

Soil microbiota plays crucial roles in maintaining the health, productivity, and nutrient cycling of terrestrial ecosystems. The persistence and prevalence of heterocyclic compounds in soil pose significant risks to soil health. However, understanding the links between heterocyclic compounds and microbial responses remains challenging due to the complexity of microbial communities and their various chemical structures. This study developed a machine-learning approach that integrates the properties of chemical structures with the diversity of soil bacteria and functions to predict the impact of heterocyclic compounds on the microbial community and improve the design of eco-friendly heterocyclic compounds. We screened the key chemical structures of heterocyclic compounds─particularly those with topological polar surface areas (<74.2 Å2 or 111.3-154.1 Å2), carboxyl groups, and dissociation constant, which maintained high soil bacterial diversity and functions, revealing threshold effects where specific structural parameters dictated microbial responses. These eco-friendly compounds stabilize communities and increase beneficial carbon and nitrogen cycle functions. By applying these design parameters, we quantitatively assessed the eco-friendliness scores of 811 heterocyclic compounds, providing a robust foundation for guiding future applications. Our study disentangles the critical chemical structure-related properties that influence the soil microbial community and establishes a computational framework for designing eco-friendly compounds with ecological benefits from an ecological perspective.

Long-term effects of combining anaerobic digestate with other organic waste products on soil microbial communities.

Agriculture is undergoing an agroecological transition characterized by adopting new practices to reduce chemical fertilizer inputs. In this context, digestates are emerging as sustainable substitutes for mineral fertilizers. However, large-scale application of digestates in agricultural fields requires rigorous studies to evaluate their long-term effects on soil microbial communities, which are crucial for ecosystem functioning and resilience. This study presents provides a comparative analysis in long-term field conditions of fertilization strategies combining annual applications of raw digestate with biennial applications of different organic waste products (OWPs)-biowaste compost (BIO), farmyard manure (FYM), and urban sewage sludge (SLU)-and compares them to combinations of the same OWPs with mineral fertilizers. The cumulative effects of repeated OWP applications, paired with two nitrogen sources-organic (digestate) and chemical (mineral fertilizer)-were assessed through soil physicochemical and microbial analyses. We hypothesized that the combined effect varied according to the N-supply sources and that this effect also depended on the type of OWP applied. Soil microbial communities were characterized using high-throughput sequencing targeting 16S and 18S ribosomal RNA genes, following DNA extraction from soil samples collected in 2022, six years after the initial digestate application. The results indicated that combining OWPs rich in stable and recalcitrant organic matter, such as BIO and FYM, with raw digestate, offers an improved fertilization practice. This approach maintains soil organic carbon (SOC) levels, increases soil phosphorus and potassium content, and stimulates microbial communities differently than nitrogen supplied via mineral fertilizers. While microbial biomass showed no significant variation across treatments, microbial diversity indices exhibited differences based on the type of OWP and nitrogen source. The fertilization strategies moderately influenced prokaryotic and fungal community structures, with distinct patterns depending on the OWP and nitrogen source. Notably, fungal communities responded more strongly to treatment variations than prokaryotic communities. This study provides new insights into the cumulative effects of substituting mineral fertilizers with digestates on soil microbial communities and soil physicochemical parameters. The sustainable development of agroecosystems significantly depends on a better understanding of the complex responses of soil microbial communities to different fertilization regimes. Future research should continue to assess the long-term impact of digestate application on soil microbiota in real agronomic field conditions, considering associated agricultural practices.

Diversity in Soil Microbes: An Essential Factor in Food Security and Human Health-A Review

A varied collection of microbes called the soil microbiome plays a major role in various human health issues and sustainable agriculture. Due to its distinct bioactive chemicals and ecological roles, soil microbiota, which is made up of a wide variety of microorganisms such as fungi, bacteria, and archaea, has great promise as therapeutic agents such as antibiotics Streptomycin, Penicillin, Erythromycin, Phosphatase enzymes etc. Moreover, through a variety of mechanisms, including nitrogen fixation, mineralization, solubilization, and nutrient mobilization, these microbes support plants growth. They also generate antagonistic chemicals, siderophores, antimicrobial agents, and hormonal substances that aid in the growth of plants, such as auxin and gibberellins. The goal of low-input agriculture is to increase long-term production while reducing the need for artificial fertilizers and pesticides. Using the possibilities of the soil microbiome promotes healthier surroundings and environmentally friendly agricultural practices, which eventually improve human health. Even though they are among the most diverse species of organisms in this habitat, hardly anything is known about them. Therefore, this study highlight the crucial role of soil microbial diversity that plays an important role in enhancing agricultural productivity, ensuring sustainable food systems, and promoting human health. It seeks to demonstrate how diverse soil microbes improve nutrient cycling, plant growth, and disease resistance, while also supporting ecosystems that are vital for long-term food security.

Chemotaxis of rhizosphere Pseudomonas sp. induced by foliar spraying of lanthanum reduces cadmium uptake by pakchoi.

Foliar application of rare earth micronutrient of lanthanum (La) exhibits great potential in reducing cadmium (Cd) uptake in crops, the underlying mechanisms controlling the interaction between Cd toxicity-relieved crops and soil microbiota are poorly understood. In this study, LaCl3 with the concentrations of 10 and 30μM was sprayed on pakchoi (Brassica chinensis L.) planting on Cd contaminated solution and soil to determine the changes of root metabolites and rhizosphere bacterial communities. Compared to the control, Cd concentration in pakchoi leaves was significantly decreased by 30.9% and 22.6% with the high group under both hydroponic and pot culture by applying 30μM LaCl3. Herein, the concrete evidence is provided that pakchoi plants in response to foliar-spraying La under soil or solution Cd toxicity can promote the root secretion of amino acids, resulting in a strong enrichment of nitrogen-related microorganisms. To probe this linkage, a Pseudomonas representative specie was isolated that had the ability of consuming alanine, the most oversecreted root exudate due to La application. Further results demonstrated that this strain had the capacities for alleviating Cd toxicity and enhancing crop growth by immobilizing Cd and secreting plant-beneficial metabolites. This study reveals a plant-extrudate-microbiome feedback loop for responding to La-relieved Cd toxicity in crops by the chemotaxis of rhizosphere Pseudomonas toward alanine secreted by pakchoi.

Deciphering physical and functional properties of chitosan-based particles for agriculture applications

Traditional methods for controlling plant pathogens rely on toxic chemicals, posing environmental and health risks. Developing sustainable, eco-friendly alternatives is crucial. Chitosan (CS)-based materials offer promising solutions for sustainable agriculture. We aimed to synthesize and characterize CS-based microparticles with varying properties and assess their antimicrobial performance to establish correlations between variations in physicochemical characteristics and their impact on performance within biological systems. We adjusted the synthesis parameters, producing particles labeled P1, P2, and P3, which have sizes of 0.19 ± 0.07 μm, 0.45 ± 0.32 μm, and 1.22 ± 0.32 μm, and zeta potentials of +7.6 ± 4.25 mV, +22 ± 3.51 mV, and + 12.9 ± 4.54 mV, respectively. Extensive toxicological screenings showed that these CS-based microparticles were non-toxic across cell cultures, mouse red blood cells, soil microbiota, nitrogen-cycling bacteria, and plant toxicity assays. Encouraged by these results, we evaluated their antimicrobial potential against economically important crop pathogens. The CS-based microparticles exhibited antimicrobial effects against the bacterium Pseudomonas syringae pv. tomato DC3000 and the fungus Fusarium solani f. sp. eumartii. Higher zeta potentials correlated with greater antimicrobial efficacy, evidenced by lower IC50 and minimum inhibitory concentration (MIC) values. These findings indicate that all three microparticles analyzed displayed antimicrobial activity against two economically significant crop pathogens, with P2 showing solid performance attributed to its physicochemical characteristics. Therefore, CS-based microparticles represent a promising, nontoxic, and environmentally friendly alternative for modern agriculture, with their biological activities potentially predictable through careful selection of physicochemical properties before the synthesis process.

Biodegradation profile and soil microbiota interactions of poly(vinyl alcohol)/starch-based fertilizers.

Enhanced efficiency fertilizers (EEFs) are critical for sustainable agriculture, providing essential nutrients while minimizing environmental impact. However, developing EEFs that effectively degrade after use remains a significant challenge. This study investigates the biodegradation and nutrient release profiles of EEFs composed of poly(vinyl alcohol) (PVA) and starch-nutrient microspheres. EEFs were developed using a dual-layered approach: spray drying to create starch-nutrient microspheres, followed by melt processing with PVA to form pastilles. A 100-day soil biodegradation test monitored CO2 release as an indicator of microbial activity and material degradation. Comprehensive analyses, including chemical (FTIR), thermal (DSC), and morphological (SEM) assessments, were conducted. The increased CO band intensity (~1640cm-1) after biodegradation indicated early stages of PVA degradation, accompanied by a rise in the glass transition temperature (Tg). Thermal analysis revealed nutrient release, as evidenced by a decrease in KNO3 peaks. Starch-based EEFs enhanced CO2 release and mycelial coverage, suggesting that starch-containing materials facilitated PVA degradation by improving microbial adhesion. This study underscores the potential of biodegradable EEFs to enhance soil health and reduce pollution, thereby contributing significantly to sustainable agriculture.

Effect of exogenous treatment with zaxinone and its mimics on rice root microbiota across different growth stages

Enhancing crops productivity to ensure food security is one of the major challenges encountering agriculture today. A promising solution is the use of biostimulants, which encompass molecules that enhance plant fitness, growth, and productivity. The regulatory metabolite zaxinone and its mimics (MiZax3 and MiZax5) showed promising results in improving the growth and yield of several crops. Here, the impact of their exogenous application on soil and rice root microbiota was investigated. Plants grown in native paddy soil were treated with zaxinone, MiZax3, and MiZax5 and the composition of bacterial and fungal communities in soil, rhizosphere, and endosphere at the tillering and the milky stage was assessed. Furthermore, shoot metabolome profile and nutrient content of the seeds were evaluated. Results show that treatment with zaxinone and its mimics predominantly influenced the root endosphere prokaryotic community, causing a partial depletion of plant-beneficial microbes at the tillering stage, followed by a recovery of the prokaryotic community structure during the milky stage. Our study provides new insights into the role of zaxinone and MiZax in the interplay between rice and its root-associated microbiota and paves the way for their practical application in the field as ecologically friendly biostimulants to enhance crop productivity.

Exploring the significance of different amendments to improve phytoremediation efficiency: focus on soil ecosystem services.

Phytoremediation is recognized as an environmentally, economically and socially efficient phytotechnology for the reclamation of polluted soils. To improve its efficiency, several strategies can be used including the optimization of agronomic practices, selection of high-performance plant species but also the application of amendments. Despite evidences of the benefits provided by different types of amendments on pollution control through several phytoremediation pathways, their contribution to other soil ecosystem functions supporting different ecosystem services remains sparsely documented. This current review aims at (i) updating the state of the art about the contribution of organic, mineral and microbial amendments in improving phytostabilization, phytoextractionof inorganic and phytodegradation oforganic pollutants and (ii) reviewing their potential beneficial effects on soil microbiota, nutrient cycling, plant growth and carbon sequestration. We found that the benefits of amendment application during phytoremediation go beyond limiting the dispersion of pollutants as they enable a more rapid recovery of soil functions leading to wider environmental, social and economic gains. Effects of amendments on plant growth are amendment-specific, and their effect on carbon balance needs more investigation. We also pointed out some research questions that should be investigated to improve amendment-assisted phytoremediation strategies and discussed some perspectives to help phytomanagement projects to improve their economic sustainability.

СРАВНИТЕЛЬНАЯ ОЦЕНКА ДЕЙСТВИЯ РАЗЛИЧНЫХ БИОУДОБРЕНИЙ В КОМПЛЕКСЕ С ЦЕОЛИТОМ НА ПРОДУКТИВНОСТЬ И МИКРОБИОЦЕНОЗ ГРЕЧИХИ

The research was conducted to assess the effect of biofertilizers on productivity and microbiocenosis of buckwheat. The experiment was conducted in 2023 in a greenhouse in the Republic of Tatarstan on buckwheat of the Nikolskaya variety. The experimental scheme included the following options: without plants (control 1); without fertilizers (control 2); N60P60K60; zeolite from the Tatar-Shatrashan deposit (particle size 0.04 mm) 1 t/ha; soaking seeds in a suspension of a consortium of microorganisms at the rate of 1 l/t per day. preparation; soaking of seeds in suspension of the biological preparation Azolene (Azotobacter vinelandii IB-4) at the rate of 1 l/t of the preparation; consortium of microorganisms + zeolite; Azolene + zeolite. The consortium of microorganisms included strains of nitrogen-fixing (Azotobacter chroococcum and Pseudomonas brassicacearum) and phosphate-mobilizing (Sphingobacterium multivorum and Achromobacter xylosoxidans) rhizobacteria isolated from the soil of Tatarstan, identified and deposited in a 1:1 ratio by suspension weight (bacterial suspension density up to 8,109 CFU/cm3). Buckwheat yields in the variants with zeolite and mineral fertilizer were 1.3 and 1.8 times higher than in the control, respectively. The maximum weight of fruits in the experiment was noted in variants with a consortium of microorganisms in pure form and together with zeolite - 2.5 and 2.9 times higher than in the control. Biofertilizers, NPK and zeolite can be arranged in the following order according to their effectiveness: consortium of microorganisms &gt; consortium of microorganisms + zeolite &gt; NPK &gt; zeolite. The use of Azolene did not lead to an increase in buckwheat yield compared to the control. During the growing season, in variants with a consortium of microorganisms, not only the best representation of agronomically significant microorganisms (ammonifiers, diazotrophs, phosphate mobilizers, actinobacteria) was noted, but also a high respiratory activity of the soil microbiota. A consortium based on autochthonous nitrogen-fixing and phosphate-mobilizing bacteria can serve as the basis for the creation of an integrated biofertilizer for a wide range of crops.