Abstract:Inhibition of mycelial growth and conidial germination of the phytopathogenic fungus, Magnaporthe grisea by zymotic fluids of Bacillus pumilus mutants and enzymatic activities of chintinase and proteinase of the identified mutants were analyzed in order to establish an efficient screening system for antagonistic abilities in Tn5 transposon library of the B.pumilus strain DX01 and further to clone genes associated with anti-phytopathogenic activity. A total of 2 633 mutants were subjected to anti-phytopathogenic activity screening and six mutants were preliminarily identified. The tests revealed that the inhibition percentage of M.grisea conidia that respectively treated with zymotic fluids of mutants Tn5-901 and Tn5-194 and the wild-type strain DX01 were 96%, 3%, and 36%. A statistically significant difference in antibacterial activity between the two mutants and the control strain DX01 were found, but the other four mutants did not exhibit a unanimous result in the multiple comparison tests for enzymatic activities and inhibition of mycelial growth with bacterial zymotic fluids. In conclusion, the evaluation of inhibition of fungal mycelial growth with spreading zymotic fluids of biocontrol bacterium is simple and high efficient, and this approach is optimal for preliminary screening of anti-phytopathogenic activity in B.pumilus.