Influence of Trichoderma asperellum and Bacillus subtilis as biocontrol and plant growth promoting agents on soil microbiota

Purpose The manipulation of soil microbiota can involve changes in microbial diversity and microbial activities, and it is carried out for practical purposes. The microbial diversity can be modified by the inoculation of beneficial microorganisms into soil or by agricultural management practices. This study provides information on the influence of introducing beneficial soil microorganisms on soil indigenous microbiota. The aim of this study was to determine how biocontrol and plant growth promoting agents Trichoderma asperellum and Bacillus subtilis and their consortium affect indigenous soil microbiota without placing emphasis on the plant as a determinant of change. Methods Experimental soil samples were treated with B. subtilis and T. asperellum and their consortium. The shift of number of bacterial and fungal CFUs in soil was determined. Biolog EcoPlate assay demonstrated the metabolic activity of microorganisms in soil. The concentration of Trichoderma genus, Firmicutes, Gammaproteobacteria and Acidobacteria DNA in soil samples was determined by molecular methods. A correlation analysis was performed between microbiological and molecular data. Results Soil treatment with T. asperellum, B. subtilis and the plant pathogenic fungus Botrytis cinerea changed the number of CFUs and amplified DNA fragments of certain taxa. The study showed that added microorganisms did not significantly affect the metabolic diversity of the community and Shannon-Wiener biodiversity index but change the utilization of carbohydrates, complex carbon compounds and organic phosphorus compounds. Conclusion Introduced biocontrol and plant growth promoting agents T. asperellum and B. subtilis survive in soil during a 60-day experiment and influence composition and functionality of indigenous populations. Whereas B. subtilis and T. asperellum and their consortium are inhibitors of the pathogenic fungus B. cinerea, this could further positively affect specific crops.