Liliya Biktasheva

The present study evaluated the phytoprotective activity of silver nanoparticles stabilized with sodium amphopolycarboxyglycinate (AgNPs-APCG) against apple fire blight caused by Erwinia amylovora. A highly colloidally stable AgNPs-APCG dispersion was prepared by borohydride chemical reduction and contained predominantly spherical metallic AgNPs with an average diameter of 10.4 ± 4.9 nm and a ζ-potential of −52.6 ± 2.4 mV. The obtained dispersion showed pronounced antibacterial activity against the E. amylovora strain, isolated from fire blight-affected shoots, with a MIC of 18.75 mg/L. In the field trial, foliar application at 5 and 25 mg/L reduced fire blight incidence and severity, with biological efficacies of 52.8% and 80.3%, respectively, and increased marketable yield by 12.0% and 16.7%. The phytoprotective efficacy of AgNPs-APCG at 5 mg/L, a concentration nominally below the in vitro MIC for E. amylovora, was consistent with a possible contribution of factors in addition to direct antibacterial activity. Supporting this possibility, AgNPs-APCG reduced carbohydrate-containing exopolysaccharide content in E. amylovora cultures to 51 ± 5% of the untreated control. Furthermore, higher activities of antioxidant enzymes were observed in AgNPs-APCG-treated apple leaves, while malondialdehyde content showed no pronounced increase, suggesting possible modulation of redox- and defense-related metabolism in treated plants. Potential environmental implications of the tested application regimes were considered based on the estimated Ag input to soil. These findings suggest that multiple pathogen- and host-associated responses may contribute to the phytoprotective effect of AgNPs-APCG and support its further evaluation as a multifunctional agent against bacterial plant diseases.

A major obstacle to optimizing soil bioremediation is the inability to monitor the molecular transformations of pollutants in situ. Traditional methods measure overall mass loss but provide little insight into the chemical restructuring of residual oil. This study proposes a methodology based on nuclear magnetic resonance spectroscopy (¹H NMR) to directly monitor the dynamics of molecular changes in soil hydrocarbons using Haplic Chernozem soil artificially contaminated with crude oil at a concentration of 20 g/kg. Using this approach, we have demonstrated that biosurfactants produced by the strain Pseudomonas putida 12os act not only as emulsifiers, enhancing bioavailability, but also exert a selective influence on the native microbial community by stimulating the activity of specialized hydrocarbon degraders. NMR data revealed that the observed increase in resin content is in fact the accumulation of oxidation intermediates. Importantly, during the 63‑day experiment we recorded a sustained reduction in the content of persistent polyaromatic structures by 33% while simultaneously increasing the content of oxygenated compounds by 83%. This molecular shift was caused by biosurfactant-induced selective activation of key catabolic genes (alkM, GP-PAH), leading to community specialization in the sequential degradation of both aliphatic and aromatic hydrocarbons. The results confirm the effectiveness of NMR spectroscopy as a tool for studying bioremediation mechanisms and indicate that biosurfactants may act not only as emulsifiers for oils but also as modulators of the catabolic potential of the soil microbiome.

Ethylenediaminetetraacetic acid, commonly used in micronutrient fertilizers as a chelating agent, enhances the availability of micronutrients to plants. However, its accumulation in the environment has numerous negative effects. The search for alternative chelating agents without these drawbacks is highly relevant. This study evaluated the impact of a novel micronutrient fertilizer based on the chelating agent 2-((1,2-dicarboxyethyl)amino)pentanedioic acid on the endophytic microbial community of lettuce grown in soil and hydroponic systems. The OTU count in soil was 1595, compared to 449 in hydroponics. In hydroponic systems, the application of 2-((1,2-dicarboxyethyl)amino)pentanedioic acid altered the abundance of several dominant bacterial taxa. In soil experiments, the effect of 2-((1,2-dicarboxyethyl)amino)pentanedioic acid on bacterial taxa was less pronounced. For endophytic bacterial communities, 12 bacterial OTUs were identified as core for lettuce leaves and roots regardless of the substrate. The OTU count in control soil root samples was 296, compared to 178 in hydroponic roots. The application of 2-((1,2-dicarboxyethyl)amino)pentanedioic acid led to slight shifts in the abundance of certain endophytic bacteria, especially in hydroponic systems. Non-metric multidimensional scaling analysis demonstrated that substrate type has the most significant influence on the composition of endophytic and substrate bacterial communities. The application of 2-((1,2-dicarboxyethyl)amino)pentanedioic acid did not significantly alter the composition of the communities. The results suggest that while 2-((1,2-dicarboxyethyl)amino)pentanedioic acid chelated fertilizer can influence the abundance of specific microbial taxa, it does not drastically disrupt the endophytic bacterial communities’ structure in lettuce grown in soil or hydroponics.

Background.Oil remains a critical resource in the global energy sector, accounting for approximately 30% of worldwide energy consumption. However, conventional primary and secondary recovery methods extract only 20-40% of oil reserves, which stimulates the development of Enhanced Oil Recovery (EOR) techniques. Among them, biological (microbial) EOR methods (MEOR), based on the application of biosurfactants synthesized by microorganisms as "green" analogs of synthetic surfactants, show high potential for mature fields with high residual oil content. Purpose. To evaluate the effectiveness of biosurfactants produced byBacillussp. 2a andPeribacillussp. 2b strains for enhancing production of hard-to-recover oil reserves. Materials and methods. The study was conducted under laboratory conditions. Lipopeptide biosurfactants extracted from cultures of Bacillus sp. 2a and Peribacillus sp. 2b strains were used. The lipopeptide nature of these biosurfactants was confirmed by infrared (IR) spectroscopy. Surface activity was evaluated by measuring surface tension using the Du Noüy ring method. The efficiency for MEOR was determined in model experiments on oil displacement from sand-packed columns using crude oil from the Romashkino field. Results. IR spectroscopy confirmed the lipopeptide composition of the biosurfactants. The biosurfactant from theBacillussp. 2a strain reduced the surface tension to 29.6 - mN m-1(peak activity at 24–48 hours), providing an additional oil recovery factor of 31.2% in a model experiment. For thePeribacillussp. 2b strain, the minimum surface tension was 52.8 mN m-1(achieved by 48 hours), with an increase in oil recovery of 23.2%. The efficiency of additional oil recovery provided by the biosurfactant from theBacillussp. 2a strain is comparable to the results obtained with a synthetic surfactant (31.2% and 29.3%, respectively).

Background. Soil quality is a key factor determining its ability to support plant growth and development, maintain ecological balance and ensure the sustainability of agroecosystems. It is determined by a set of physicochemical and biological soil properties that are closely interrelated and affect its fertility, structure and ecological functions. However, the nature of land use can have a significant impact on these soil properties and, consequently, on its quality. Therefore, the results of this study will contribute to the optimal and rational management of soil ecosystems. Purpose. The gray forest soil (Haplic Luvisol) plots with different types of land use in the Laishevsky district of the Republic of Tatarstan were studied. The influence of different types of land use (arable land, hay meadow, mowing without phytomass removal, fallow land) on the physicochemical (humidity, granulometric composition, organic matter content, nitrate content) and microbiological (respiratory activity, microbial biomass, metabolic activity) parameters of the gray forest soil was assessed. Materials and methods. Four soil pits were laid in the Laishevsky District of the Republic of Tatarstan on sites with the following types of land use: arable land, hay meadow, mown without phytomass removal, and fallow land. The soil was analyzed for its physicochemical properties: moisture according to GOST 5180-2015, particle size distribution using a Microtrac Bluewave laser diffractometer (Microtrac Retsch GmbH, Germany), organic matter content according to GOST 27753.10-88, and nitrate content according to GOST 26951-86. The soil microbiological characteristics were analyzed: respiration activity according to ISO 16072:2002 and microbial biomass according to ISO 14240-1:1997. The total metabolic activity of the soil microbial community was determined using the AWCD (average cell color density) index and commercial Biolog Ecoplates (Biolog Inc., USA). Results. It was found that the arable soil profile is characterized by a more uniform distribution of organic matter content, a higher content of nitrates (13%) and microbial biomass (145.5 mg/kg). Homogenization of the upper layer and the associated more uniform distribution of sand and silt fractions were revealed in the soil under arable land. Differentiation of particle size distribution along the profile, higher respiration (up to 0.76 μg C-CO2/g*h) and metabolic activity, as well as accumulation of organic matter were observed in the soils of natural land use types. Conclusion. The conducted studies confirmed the significant influence of the type of land use on the physicochemical and biological properties of gray forest soil. Intensive agricultural activity, in particular the use of soil for arable land, leads to changes in its profile. Reducing the anthropogenic impact on the soil helps to preserve and improve soil properties. The results obtained indicate the need for rational management of soil resources aimed at minimizing degradation processes and maintaining the ecological functions of soils. Optimization of land use taking into account the identified patterns will ensure sustainable soil fertility and the preservation of their biodiversity. EDN: MCGAOQ

Background.A comprehensive study of the factors affecting the optimization of the composting process is essential. The results of this study will contribute to a more efficient and sustainable management of chicken manure waste. By optimizing the composting process with a biochar additive, the environmental and sanitary risks associated with unprocessed manure can be reduced. The resulting compost will be a valuable organic fertilizer. Overall, this study can contribute to the development of organic animal waste management practices. Purpose.Evaluation of the effect of different doses of biochar based on chicken manure on physicochemical (temperature, humidity, content of biogenic elements C, N, P, K) and microbiological (respiration activity, metabolic activity of microorganisms) parameters of chicken manure composting, as well as on the phytotoxicity of the finished compost with respect to the test subject of oat plants (Avena sativaL.). Materials and methods.The object of the study was litter chicken manure with a sawdust content of less than 25%. To prepare compost mixtures, biochar was added to the original chicken manure at a dose of 0, 1, 5, 10, 15% (w:w), as well as sawdust in an amount of 33% (w:w). Composting was carried out for 150 days at a temperature of 20 °C. The content of total carbon and total nitrogen was estimated using an elemental analyzer according to the Dumas-Pregl method. The size and nature of biochar pores were determined by scanning electron microscopy. The specific surface area of biochar was estimated in accordance with the method for determining the specific surface area from isotherms in the Brunauer-Emmett-Teller (BET) model and the laser diffraction method according to GOST R 8.777-2011. Humidity was determined by the air-thermal method in accordance with GOST 28268-89. Respiration activity was assessed according to ISO 14240-1. The total metabolic activity of microbial communities of compost mixtures was determined using the AWCD (average cell color density) index and Biolog Ecoplates (Biolog Inc., USA). The phytotoxicity of the compost mixtures was assessed using the germination index (GI) of oat (Avena sativaL.) plants in accordance with ISO 11269.1:2012. Results.It was shown that biochar application had no significant effect on the composting temperature regime - all compost mixtures studied were characterized by traditional temperature dynamics. To maintain the recommended moisture level, the most optimal doses were biochar doses of 10 and 15%. A positive effect on the content of nutrients C, N, P and K in the final compost mixtures was found when using 10 and 15% biochar. No influence of biochar on microbiological parameters of composting (respiration activity, metabolic activity) was observed, while maintaining positive dynamics of the composting process. Evaluation of biochar influence on phytotoxicity of composts showed that when using the highest dose of biochar (15%) the maximum value of germination index GI (118%) was found for oat plants (Avena sativaL.). Conclusion.Thus, this study highlights the potential of using biochar derived from chicken manure to improve the composting process and enhance the quality of the final product. The results show that the incorporation of biochar into the composting process of chicken manure not only contributes to better nutrient retention, but also promotes healthier plant growth, thus offering a sustainable solution for poultry waste management.

Experimental studies published to date on the effects of silver nanoparticles (AgNPs) on plants have yielded highly contradictory results: reported outcomes range from growth inhibition to stimulation. The objective of this research was to test the hypothesis that the ontogenetic stage at the time of exposure to AgNPs is a key determinant of both the qualitative profile and quantitative magnitude of plant responses. For this purpose, laboratory seed priming and small-plot field experiments with wheat plants (Triticum aestivum L.) treated with stabilized dispersions of AgNPs at 1–100 mg∙L⁻¹ were conducted. It was shown that seed priming with low concentrations of AgNPs (1–5 mg∙L⁻¹) did not affect wheat seedling growth, whereas dispersions at ≥25 mg∙L⁻¹ suppressed development. In agreement, antioxidant enzyme activities (POD, CAT, PPO) increased at 1–5 mg·L⁻¹ and decreased at 100 mg·L⁻¹. By contrast, foliar treatments of field-grown wheat increased plant population density, plant height, spike structure metrics, and grain yield. The optimal regimen—three foliar applications at 5 mg·L⁻¹—increased grain yield by 12.1% from 5.89 t·ha⁻¹ to 6.60 t·ha⁻¹. At low doses of AgNPs, activities of peroxidase, catalase, and polyphenol oxidase in seedlings tissues increased, indicating activation of nonspecific defense mechanisms; at higher concentrations, activities of these enzymes decreased, indicating antioxidant system exhaustion and dysfunction. The findings demonstrate dose- and stage-dependent effects and corroborate the central role of the developmental stage of wheat in determining responses to AgNPs, indicating opportunities to optimize stage-aware, low-dose application regimes to enhance productivity while minimizing phytotoxic risk.

Increasing demand for high-quality food is driving the development of biologized farming methods, which involve the use of microorganisms, including endophytes, to stimulate plant growth. However, research on the composition of endosphere microbiomes is limited. The study presents an analysis of the bacterial endophytic microbiome in lettuce seeds (Lactuca sativa L., cv. Ozornik) using high-throughput sequencing of 16S rRNA amplicons. It evaluates the taxonomic composition and putative functional properties of seed endophytic bacteria. The microbial community exhibited low diversity (Shannon index ranged from 1.1 to 1.84, Simpson index from 0.57 to 0.83). The bacterial endophytic community of lettuce seeds was dominated by Pseudomonadota (83%), Actinomycetota (14%), and Bacillota (3%). The genera identified within the microbiome included Pantoea (32%), Rhodococcus (13%), Candidatus Profftella (13%), Janthinobacterium (7%), Pseudomonas (9%), Enterococcus (3%), and Alcaligenes (2%), which exhibit a broad spectrum of beneficial properties: plant growth promotion (PGPB), suppression of phytopathogens, enhanced stress tolerance, participation in contaminant biodegradation, and heavy metal detoxification. The structure and functional potential of the microbiome vary between samples, potentially due to differences in source material and cultivation conditions. The obtained results expand our understanding of the composition and functions of endophytic bacteria in lettuce seeds, which is important for the development of novel biocontrol agents for plants consumed by humans in an unprocessed form.

The study of the microbial community of wells is a methodologically complex, but urgent problem. In the course of our work, five samples of oil wells were selected from one deposit of the Romashkino field. The samples were subjected to nucleic acid extraction using three methods—direct DNA extraction, and after enrichment using aerobic and anaerobic cultivation methods. In three samples from wells W1–W3, extraction after anaerobic enrichment was successful. Effective aerobic cultivation was possible in all five samples. All three of these samples represented the aqueous part of the produced fluid; samples from wells W4 and W5, where extraction was difficult, represented the oil part. During the analysis of the microbial community in enrichment cultures from wells W1–W3, exogenous microorganisms such as Desulfovibrio, Acetobacterium, Bacillus, and Georgenia were discovered, which can be explained by the long-term exploitation of this section of the field. In one sample from well W1, community information was obtained using direct extraction and anaerobic enrichment. It was found that the microbial community changed significantly after enrichment, and its diversity decreased. At the same time, however, the functional profile of microorganisms has not changed, and sulfate-reducing microorganisms dominate in both samples. Thus, the results of the work allow us to make an assumption about the physicochemical parameters of samples in which the study of the microbial community is possible. In addition, it became known that well W1 needs to control the process of biological acidification and has a high risk of equipment corrosion.