Bacillus spp. isolated from pepper leaves and their function and inhibition of the fungal plant pathogen Colletotrichum scovillei

Abstract

BackgroundPepper is a popular ingredient in many Chinese households; however, anthracnose caused by Colletotrichum spp. has greatly decreased pepper production. The genus Bacillus is widely known for its important role in the development and protection of plants from phytopathogenic fungi.ResultsFifty-eight endophytic strains were isolated from pepper leaves and tested for antifungal activity in this study. Specifically, L1-7 and L3-5 displayed growth inhibition rates of 79 and 80% against C. scovillei mycelium, respectively, while 25 of these strains all had growth inhibition rates of greater than 60%. Bacillus amyloliquefaciens and B. velezensis, based on culture and morphological identification with 16S rDNA and gyrB gene sequence analyses, were determined to be the respective species L1-7 and L3-5. Additionally, it was discovered that these two antagonistic endophytic bacteria could fix nitrogen, produce indoleacetic acid (IAA) and have a high salt tolerance. Pot experiments again showed excellent control of the pathogen C. scovillei by L1-7 and L3-5, with 80.64 and 73.39% control, respectively. Therefore, B. amyloliquefaciens (L1-7) and B. velezensis (L3-5) can be applied as biological control agents to protect peppers against C. scovillei-caused anthracnose.ConclusionBacillus amyloliquefaciens (L1-7) and B. velezensis (L3-5) can be applied as biological control agents to protect peppers against C. scovillei-caused anthracnose. Thus, they can serve as promising biocontrol agents and plant growth promoters, and future research on the pertinent bacteria will serve as a useful guide for the creation of microbial resources.