Identification of microorganisms found in the roots of plants and in the rhizospheric soil of the dried bed of the Aral Sea
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Abstract
In the context of global climate change and increasing environmental degradation, extreme ecosystems such as the dried bottom of the Aral Sea have become important natural laboratories for studying plant–microbe interactions under severe abiotic stress conditions. These environments, characterized by high salinity, aridity, and complex geochemical factors, significantly influence the structure and function of rhizosphere microbial communities. However, the diversity and ecological role of cultivable microorganisms associated with halophytic plants in such environments remain insufficiently explored.
The aim of the study was to identify cultivable microorganisms associated with the roots and rhizosphere of halophytic plants, particularly Salsola richteri, growing in the Aralkum region, and to evaluate their ecological and biotechnological potential.
Methods. The study employed classical microbiological and analytical approaches, including soil and root sampling from the Aral Sea dried seabed, serial dilution and streak plate techniques for isolation of pure bacterial cultures, and morphological, physiological, and Gram staining analyses. Precise taxonomic identification of isolates was carried out using MALDI-TOF mass spectrometry. Additionally, salt tolerance assays were performed to assess the adaptive capacity of isolates under hypersaline conditions.
Results. A total of 13 bacterial isolates were obtained, including 40% Gram-positive and 60% Gram-negative bacteria, predominantly rod-shaped forms. Taxonomic analysis revealed that the isolates mainly belonged to the genera Bacillus, Enterobacter, Providencia, Pseudomonas, and Rhodococcus. Among them, Rhodococcus ruber and Enterobacter cancerogenus were the most frequently detected species. Several isolates demonstrated high salinity tolerance, with the ability to grow at NaCl concentrations up to 12–14%, indicating strong physiological adaptation to extreme environmental conditions.
The predominance of halotolerant and stress-adapted microorganisms in the rhizosphere suggests their active involvement in plant survival under harsh conditions. These microorganisms likely contribute to plant adaptation through mechanisms such as osmotic regulation, nutrient mobilization, and stimulation of plant growth.
Conclusion. The obtained results highlight the ecological significance of rhizosphere microbiota in the Aral Sea region and demonstrate their potential application in phytomelioration, soil restoration, and the development of biofertilizers. The identified strains represent promising candidates for future biotechnological applications aimed at improving plant resilience in saline and arid environments.
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