ENZYMATIC PROPERTIES AND PLANT GROWTH-PROMOTING POTENTIAL OF SOYBEAN RHIZOBACTERIA

Abstract

This study presents the results of isolation and characterization of rhizobacteria with phosphate-solubilizing ability from the rhizosphere of the soybean cultivar Zhansaya grown in the Almaty region. A total of ten bacterial isolates were obtained, of which three were identified as Gram-negative and seven as Gram-positive microorganisms. Their phosphate-solubilizing capacity and enzymatic activities were evaluated. Four isolates exhibited pronounced phosphate-solubilizing potential, with the highest solubilization index values recorded for strains SJ3 (0.93±0.11), SJ5 (0.79±0.012), SJ9 (0.49±0.01), and SJ10 (0.49±0.01). Among these isolates, high protease activity was observed in SJ3 (2.6±0.26), SJ5 (2.73±0.25), and SJ9 (2.83±0.29), while amylase activity was detected in SJ3 (2.6±0.45), SJ9 (2.5±0.17), and SJ10 (2.65±0.15). The strongest cellulase activity was observed in SJ3 (2.83±0.26) and SJ10 (2.8±0.22), whereas lipase activity was not detected in any of the isolates.

Additionally, the isolates demonstrated the ability to utilize citrate and ferment carbohydrates: three of the four isolates fermented glucose, and one of them produced gas during fermentation. The results indicate that the enzymatic activity of rhizobacteria plays a key role in their antagonistic potential, contributing to the degradation of phytopathogen cell wall structures, suppression of their growth, and enhancement of plant resistance to diseases. The selected strains represent promising candidates for further development as agronomically valuable bioagents that promote sustainable growth and increase soybean productivity.