Biocontrol Activity of <i>Bacillus megaterium</i> BM344-1 against Toxigenic Fungi

Abstract

Mycotoxins are secondary metabolites of some fungal species and represent important contaminants of food and feed. This study aimed to explore the biological control activity of <i>Bacillus megaterium</i> BM344-1 volatile organic compounds (VOCs) on the growth and mycotoxin production of single representatives of the toxigenic species <i>Aspergillus flavus</i>, <i>Aspergillus carbonarius</i>, <i>Penicillium verrucosum</i>, and <i>Fusarium verticillioides</i>. <i>In vitro</i> co-incubation experiments indicated the <i>P. verrucosum</i> isolate as the most sensitive one, with a growth inhibition ratio of 66.7%, followed by <i>A. flavus</i> (29.4%) and <i>F. verticillioides</i> (18.2%). Exposure of <i>A. flavus</i>, <i>P. verrucosum,</i> and <i>F. verticillioides</i> to BM344-1 VOCs resulted in complete inhibition of aflatoxins (AFB₁, AFG₁, and AFG₂), ochratoxin A, and fumonisin B₁ (FB₁) synthesis on artificial media, respectively. <i>In vivo</i> experiments on maize kernels showed 51% inhibition of fungal growth on ears simultaneously infected with <i>A. flavus</i> spores and exposed to BM344-1 volatiles. Likewise, AF synthesis by <i>A. flavus</i> was significantly (<i>p</i> < 0.05) inhibited (25.34 ± 6.72 μg/kg) by bacterial volatiles as compared to that in control maize ears (91.81 ± 29.10 μg/kg). Gas chromatography-tandem mass spectrometry-based analysis of headspace volatiles revealed hexadecanoic acid methyl ester (palmitic acid) and tetracosane as bioactive compounds in the BM344-1 volatilome. Bacterial volatiles have promising potential to control the growth and mycotoxin synthesis of toxigenic fungi and may present valuable aid in the efforts to warrant food and feed safety.