Abstract: A total of 486 bacterial isolates were obtained from different rice rhizosphere soil samples. Twelve out of them showed antagonistic activities against Magnaporthe grisea using both in vitro dual culture method and microculture method. In particular, strains B4, B8, B18, B31, B34, B73 and B74 showed more than 80% inhibition in the hyphal growth of M. oryzae, while spores germination of M. grisea were completely inhibited by the supernatants of these antagonistic bacteria. Furthermore, these antagonistic bacteria were able to inhibit the hyphal growth of Rhizoctonia solani, Sclerotinia sclerotiorum, Fusarium graminearum, Colletotrichum gloeosporioides and Fusarium oxysporum f. sp. cucumerinum and were identified as Bacillus subtilis. In addition, strains B1, B43 and B44 of Bacillus pumilus showed a moderate inhibition in the hyphal growth and spores germination of M. grisea and a slight inhibition in the hyphal growth of R. solani, while strains B48 and B59 of Streptomyces showed strong inhibition in the hyphal growth and slight inhibition in spore germination and appressorium formation of M. grisea.

Key words: Magnaporthe grisea, antagonistic bacteria, appressorium