Partial Purification and Characterization of Antifungal Peptides Produced by Bacillus amyloliquefaciens PEP3 Against Phytophthora capsici

Abstract

The prevalence of antibiotic-resistant microorganisms has triggered the exploration for novel antimicrobial compounds. Peptides are biological molecules that are found in all living organisms. They play key roles in many biological processes including organism's defense. We have previously isolated Bacillus species (Bacillus amyloliquefaciens PEP3) that showed antagonistic properties against fungi. Metabolites precipitates obtained from B. amyloliquefaciens PEP3 showed antifungal activity against plant pathogenic fungus, Phytophthora capsici. Further analysis showed that these metabolites were stable in the pH range of 6 to 8 and temperatures of between 25°C to 85°C after which it began to lose its activity. Polyacrylamide gel analysis indicated that the molecular weight of the metabolites to be approximately 5 kDa. The presence of biosynthetic lipopeptides producing genes namely ituD, srfA, fenD and Ipa-14 genes were detected via the use of specific primers. The metabolites were then isolated via methanol extraction, however none of the major lipopetides family were detected using liquid chromatogrpahy-mass spectrometry (LC-MS). Nevertheless, the results derived from this work suggested that B. amyloliquefaciens PEP3 to have biocontrol research value and warrants further analysis.