ANTAGONISTIC CHARACTERISTICS OF Bacillus amyloliquefaciens D19 AGAINST Colletotrichum siamense

Abstract

Anthracnose disease caused by the fungus Colletotrichum affects many crops and reduces crop yields. Controlling this disease by biological methods and reducing the use of chemicals is of increasing interest, in which Bacillus strains are potential candidates. In this study, the antagonistic characteristics of Bacillus amyloliquefaciens D19 on Colletotrichum siamense were investigated. The obtained results showed that the B. amyloliquefaciens D19 was able to biosynthesize enzymes such as chitinase, protease, cellulase, and the bacterial suspension negatively affect the fungal cell wall which led to swelling, breakage, folding, and cell lysis of the fungal mycelia. The activity of the bacterial culture also showed heat stability with 66.4%-76.9% remaining antifungal activity after 15 minutes of incubation at 60℃-80℃ and 43.6% after 15 minutes of incubation at 90℃. In addition, the bacterial culture also showed pH stability with 75,0%-93,0% of residual activity after 2 hours treatment at pH 5.0-10.0. Furthermore, in vivo antagonistic test on mango fruit model showed that B. amyloliquefaciens D19 reduced more than 98.7% of the disease severity caused by C. siamense. Thus, B. amyloliquefaciens D19 is a potential candidate for biological control of C. siamense, which help to prevent anthracnose disease on many crops.