This review investigates the multifaceted roles of nitrogen-fixing and phosphate-mobilizing bacteria in natural ecosystems, with a particular focus on their contributions to plant growth and sustainable soil management. These microbial communities contribute substantially to nutrient cycling by converting atmospheric nitrogen into plant-available forms and mobilizing insoluble phosphorus in soil, thereby enhancing soil fertility and promoting sustainable plant productivity. This review synthesizes current knowledge on the mechanisms underlying biological nitrogen fixation, phosphate solubilization and mineralization, and the production of plant growth–promoting metabolites. Particular attention is given to plant–microbe interactions and their role in improving nutrient availability, regulating plant physiological processes, and enhancing tolerance to abiotic stresses such as salinity, drought, and heavy metal contamination. The findings underscore the ecological importance of these plant-associated microbial communities and highlight their potential applications in biofertilizer and biostimulant development for sustainable agriculture and reduced dependence on synthetic fertilizers.

This study presents a comprehensive characterization of actinobacteria isolated from soils subjected to both anthropogenic pollution and secondary salinization. As a result of microbiological screening, two promising strains were selected — Streptomyces violaceorubidus strain N3 and Streptomyces rochei strain N4 — which demonstrated high salt tolerance, active colony and biomass formation, and pronounced antagonistic activity against several phytopathogenic fungi. Molecular genetic identification based on 16S rRNA gene sequencing, followed by phylogenetic analysis, confirmed the taxonomic affiliation of the isolates. Experimental data showed that both strains produce the phytohormone indole-3-acetic acid (IAA), exopolysaccharides (EPS), and the enzyme ACC deaminase, both under normal conditions and under salt stress (300 mM NaCl). Under saline conditions, an increase was observed in IAA production (by 31–34%), EPS synthesis (by 39–47%), and ACC deaminase activity (up to 42.8 nmol α-ketobutyrate/mg protein/h). The revealed physiological and biochemical traits suggest that S. violaceorubidus N3 and S. rochei N4 have high potential as microbial inoculants for enhancing plant resistance to abiotic (salt stress) and biotic (phytopathogens) environmental factors.

Soil microorganisms play a crucial role in maintaining ecosystem stability and soil fertility; however, long-term pesticide contamination can significantly disrupt microbial functioning. The present study provides a comprehensive assessment of the microbiological and biochemical status of soils chronically contaminated with pesticides at a chemical burial site and adjacent areas. Soil samples were collected from several zones within the landfill and surrounding territories, including a reference site with minimal anthropogenic impact. The abundance and structure of major physiological groups of microorganisms were determined using culture-based methods, while soil enzymatic activities (catalase, peroxidase, polyphenol oxidase, and invertase) were assessed as indicators of biological activity. Residual concentrations of organochlorine pesticides were analyzed using gas chromatography with an electron capture detector. The results revealed a pronounced suppression of enzymatic activity and a significant reduction in microbial abundance in contaminated soils compared to the control. The most severe disturbances were observed in the central, western, and eastern zones of the burial site, characterized by elevated concentrations of dieldrin and endrin exceeding permissible levels by tens to hundreds of times. Bacterial communities dominated the microbial structure, whereas fungi and actinomycetes were strongly suppressed, indicating degradation of soil ecological functions. Spatial heterogeneity of biological responses suggested partial adaptation or limited recovery in peripheral zones. These findings demonstrate that even localized pesticide contamination leads to persistent impairment of soil microbial activity and enzymatic functioning. The results emphasize the importance of integrated microbiological and biochemical indicators for environmental monitoring and provide a scientific basis for the development of soil bioremediation strategies in chronically contaminated areas.

This study focuses on the extracellular enzymatic activity of the dominant bacterial species Bacillus sp. isolated from saline soils of the Fergana region. Among more than 25 isolates studied, isolate No. 2, obtained from the topsoil layer (0–15 cm), and exhibited the highest hydrolytic activity. Notably high activity was observed for pectinase and amylase, with hydrolysis zones ranging from 38 to 45 mm. Moderate activity was shown by xylanase, cellulase, protease, and lipase, with hydrolysis zones between 24 and 34 mm. Based on molecular genetic analysis of the 16S rRNA gene sequence, the highly active dominant strain was identified as Bacillus velezensis TM. Keywords: Soil, isolates, bacteria, identification, Bacillus velezensis, hydrolases, pectinase, amylase, xylanase, protease, cellulase, lipase

Programmed cell death (PCD) is a complex mechanism induced by environmental stress (ePCD) or developmental processes (dPCD). ePCD can be triggered by various types of unfavorable abiotic conditions, including salinity stress. Exposure to high concentrations of salt not only declines the morphological features of plants but also severely affects biochemical and molecular processes. Furthermore, plant activates numerous defense mechanisms, which take place in different organelles in a plant cell. It includes ionic, osmotic and oxidative damage in the plasma membrane, mitochondria, chloroplasts, vacuole and nucleus. Main disturbance in the plasma membrane is characterized by a decline in the transport system, ROS accumulation and Ca2+ influx. Mitochondrial dysfunction is rightly related to high accumulation of ROS, activation of protective pathways such as AOX, UCPs, GABA shunt, and cytochrome c release. Moreover, photosynthetic rate is highly decreased related to a decline in chlorophyll content. Vacuoles integrate osmotic and ionic signals by sequestering Na+ through NHX antiporters and V-ATPase activity, but when this system collapses and Ca2+ converge on the nucleus. Moreover, overproduction of ROS acts as a signal molecule to EXECUTER proteins in chloroplast-nuclear communication. Salinization activates osmotic, ionic and oxidative signals that result in chromatin degradation. Altogether, those interconnected processes lead to the PCD.