In vitro antifungal potential of Bacillus spp. isolates as biocontrol agents

Abstract

Plant diseases caused by infection with pathogenic fungi can lead to the reduction in the capacity of plant growth or can cause far more serious damage, leading to the death of plants and significant losses in food production. Numerous recent studies are devoted to the investigation of bacteria from genus Bacillus as producers of secondary metabolites that can be used in the control of different plant pathogens. In this study, strong antifungal effect of lipopeptide extracts towards 11 fungi tested was observed, with lowest recorded minimal inhibitory concentrations of 0.008 mg/ml against Fusarium semitectum. In the analysis of the interaction of lipopeptide extracts mutually, as well as in combination with essential oils, the existence of a synergistic effect in vitro was shown. In combination of isolate SS12.6 extract and savory oil on the growth of Alternaria alternata, as well as in combination of the same extract and thyme oil in acting against Fusarium nygamai, synergistic effect was achieved. The combination of both oils and extract of SS12.6 showed synergistic activity only against Fusarium solani. To date, it has been shown that the combination of complementary biological approaches with additive and/or synergistic effect may provide greater consistency and efficiency in biocontrol, so in that sense there is a growing interest for agents that could possible act as replacement of conventional synthetic fungicides in protection of cultivated plants from phytopathogenic fungi.