Effectiveness of the Bacillus sp. SP-A9 Strain as a Biological Control Agent for Spring Wheat (Triticum aestivum L.)

The SP-A9 strain of Bacillus sp., which is most closely related to Bacillus subtilis, demonstrated excellent antifungal properties in laboratory analyses. The percentage of inhibition in the dual culture test was similar for all investigated phytopathogens (Fusarium culmorum, F. oxysporum and Monographella nivalis) at approximately 46%. The analyzed strain was found to be cellulolytic and strongly chitinolytic, and its biochemical properties indicate that it easily adapted to various environmental conditions. The strain's sporulation ability and high proliferation rate in acidic, alkaline, and highly saline environments (9% NaCl) further confirmed its adaptability to adverse conditions. In a pot experiment, the basic biometric parameters of spring wheat grain inoculated with Bacillus sp. SP-A9 were not modified, but a significant increase in grain yield was observed (by 18% in soil contaminated with F. culmorum and by 19% in soil contaminated with F. oxysporum). The increase in yield was correlated with the number of wheat plants, which suggests that the analyzed strain minimized the pathogen-induced inhibition of plant growth. Bacillus sp. SP-A9 can reduce economic losses resulting from diseases caused by fungi of the genus Fusarium and contribute to reduced use of crop protection chemicals, thus minimizing environmental pollution.