Antifungal potential of Lactobacillus bioactive metabolites: synergistic interactions with food preservatives and molecular docking insights

The antifungal activity of bioactive metabolites from Lactobacillus casei EMCC 1093 against mycotoxigenic fungi was investigated. Bacterial extract using ethyl acetate showed activity against nine fungal strains. The highest activity was observed against Fusarium verticillioides (19 mm) and Penicillium verrucosum (18.0 mm). Thin layer chromatography (TLC) bio-autography of Lb. casei extract detected a clear inhibition zone against all tested fungi at bands of Rf 0.19, 0.28, 0.38, and 0.46. The GC-MS extract analysis revealed 18 compounds, where Butylated Hydroxytoluene (BHT), butanoic, benzoic, and lactic acids were the most abundant. The minimal inhibitory concentration (MIC) values for Lactobacillus. casei extract, sodium benzoate, and potassium sorbate were found to range from 0.8 to 2.2, 1.5-3.5, and 2.1-3.1 mg/ mL, respectively. Checkerboard assay showed a synergistic combination between the extract and sodium benzoate against Aspergillus westerdijikia, Fusarium verticillioides, and Fusarium proliferatum, with fractional inhibitory concentration index values ranging from 0.38 to 0.50. The extract combination with potassium sorbate observed synergistic effects against Aspergillus flavus, A. parasiticus, A. westerdijikia and additive effects against A. niger, A. ochraceus, A. carbonarus, F. verticillioides, F. proliferatum, and P. verrucosum. In silico studies provided insights into the molecular interactions and binding affinities between the extract and fungal proteins, highlighting the potential application in food preservation, and molecular dynamic simulations confirmed the inhibitory effect against toxigenic fungi. The study indicated the pioneer prevention and reduction impact of bacterial ethyl acetate extract against mycotoxigenic fungi compared to traditional preservatives to apply in the food production chain.