Influence of Bacillus subtilis B068150 on cucumber rhizosphere microbial composition as a plant protective agent

Abstract

Our aim was to investigate factors that influenced bacterial and fungal community composition in the cucumber rhizosphere with the addition of Bacillus subtilis B068150 in soils. Using pyrosequencing, we tracked changes in total bacterial and fungal community composition and structures in cucumber rhizosphere planted in clay, loam and sandy soils and inoculated with B. subtilis B068150. B. subtilis B068150 colonized the rhizosphere of cucumber without altering the indigenous microbial community composition. B068150 strain did not significantly affect microbial diversity in cucumber rhizosphere, but both soils texture and chemistry did, based on principal coordinates analysis (PCoA), hierarchical clustering in UniFrac, and canonical correspondence analysis (CCA). Shannon diversity values (H′) suggest that rhizosphere diversity varied among the three soils with the significant highest diversity observed in loamy soil. Fungi were dominated by Ascomycota, Chytridiomycota, Basidiomycotina, with Ascomycota accounting for 29.1%. Fusarium was found only in cucumber rhizosphere grown in loamy soil; however, this did not affect the health of cucumber in three loamy soils during the three months study. Bacillus subtilis B068150 could be an environmental compatible plant protective agent in soils depending on the soil type.