Isolation of a potential antifungal Bacillus subtilis 37-JM07 strain from straw and its biocontrol efficacy to combat green mold diseaseof commercial mushroom, Pleurotus ostreatus

Nine Bacillus strains were isolated from straw used in composting for mushroomcultivation and studied for their antifungal potential. The isolate 37-JM07 showed growth inhibition of all five phytopathogenic fungi used in spot inoculation method and it was identified as Bacillus subtilis. In vitro antagonism assay using single streak and double streak methods of dual culture technique has revealed the immense potential of the B. subtilis 37-JM07 with broad spectrum antifungal activity against 12 phytopathogenic fungi. In addition, the isolate 37-JM07 also could inhibit two gram positive bacteria in some extent. Cell free culture supernatant without concentration failed to suppress the growth of any fungi tested. In vivo field experiment resulted in 100%elimination of incidence of green mold disease in mushroom cultivation caused by Trichoderma harzianum due to treatment with B. subtilis 37-JM07.Moreover, about a 30%increase of mushroom yield over uninoculated control was also contributed by this potential Bacillus biocontrol agent.