Sensitivities of three species of Bacillus to five common chemicals used in tobacco field

Bacillus spp. is one type of the important biocontrol bacteria in agriculture. Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus polymyxa were three biocontrol bacteria against tobacco diseases, which were isolated from early study. Special compound fertilizer for tobacco m(N):m(P2O5):m(K2O)=10:10:25, calcium oxide, metalaxyl, mancozeb and streptomycin sulfate, which used frequently in tobacco field, against those three Bacillus species were evaluated.The results showed that metalaxyl had no effect on growth of B. subtilis, B. amyloliquefaciens and B. polymyxa, while compound fertilizer and calcium oxide could enhance the growth of the three bacteria. Mancozeb and streptomycin sulfate, however, significantly inhibited the growth of them, with EC50 values of 14.15, 11.88 and 11.30 μg/mL, and 5.20, 5.69 and 2.64 μg/mL, respectively.