Abstract

Although many Bacillus species are known to be good antibiotic producers capable of acting as biocontrol agents, the underlying antimicrobial mechanisms are often poorly understood. In this study, 3 Bacillus strains out of 30, demonstrating over 55% mycelial inhibition against Mycosphaerella musicola as well as significant control in plate assays, were examined for the presence of antibiotic biosynthetic genes. The use of 16S rRNA revealed that the three strains belonged to Bacillus amyloliquefaciens (BB30), Bacillus atrophaeus (BB15) and Bacillus subtilis (BB13). Sequence analysis of purified PCR products revealed homology with corresponding genes from other Bacillus sp. in the GenBank database. Primers specific for iturin D, surfactin, bacillomycin D, bacillomycin A, fengycin and zwittermycin A were used to amplify biosynthetic genes from these Bacillus strains using polymerase chain reaction (PCR). This study reveals the equivalent capability of different Bacillus strains from various microhabitats to produce the above-mentioned antibiotics and highlights the possibility of using some strains as potential biocontrol agents under different microhabitats distant from their original habitat. Furthermore, it will enable researchers to develop rational strategies for the application of the antagonists and their metabolites within an agroecosystem.

Key words:  Bacillus sp., antagonism, lipopeptides, polymerase chain reaction (PCR).