Selecting Bacillus spp. Antagonist of Fungal Phytopathogen Phytophthora infestans Causing Tomato Late Blight

The late blight caused by phytopathogen Phytophthora infestans has been one of the serious disease-causing yields and quality losses of tomato production in Vietnam. To control the fungal disease, chemical fungicides have been overused causing concerns about the ecological risks and human health, especially fungal resistance. Therefore, using natural products from beneficial microorganisms as a safer strategy is getting attention. The present study focused on the isolation of indigenous Bacillus sp. with potential antifungal activity against Phytophthora infestans with the aim to contribute to the diversification and improving the quality of biological control products Bacillus spp. in Vietnam. From 21 strains Bacillus spp. (marked BV1 - BV21) being isolated from different tomato farms in Danang City, Vietnam, Bacillus velezensis BV 16 was selected based on the most potential antagonistic strain in controlling fungal plant pathogen Phytophthora infestans attacking the tomato tree. The strongest inhibition of mycelial growth on P. infestans of Bacillus velezensis BV16 was recorded with 88.89% of growth inhibition percentage. The results also showed that strong activity of chitinase, protease and cellulase in the BV16 strain are consistent with the novel growth control of Phytophthora infestans.