INHIBITION OF AFLATOXIGENIC FUNGI BY LACTIC ACID BACTERIA ISOLATED FROM FERMENTED MAIZE SLURRY

Abstract

Toxigenic fungi are persistent contaminants of food and food products. This study aims at the biocontrol of toxigenic fungi. The inhibitory activity of Lactic acid bacteria (LAB) isolated from fermented cereal slurry against toxigenic Aspergillus isolated from maize was investigated. The antagonistic compounds produced by LAB were identified using gas chromatography-mass spectrometry (GCMS). Toxigenic Aspergillus flavus and A. parasiticus were isolated from maize after screening with an ammonium hydroxide test, and their aflatoxin levels were quantified to be 877 and 797 ng g^-1 respectively. Lactobacillus fermentum and Lactobacillus paraplantarum were isolated and their culture-free supernatants (CFS) had a mean inhibitory zone of 15 ± 0.4 to 18 ± 0.6 mm. They were sensitive to pH but slight loss of inhibitory activity when treated with proteolytic enzymes. The inhibitory CFS was subjected to GC-MS. Among the compounds detected, lactic acid, benzenepropanoic acid, 4-hydroxy, pyrrolo [1, 2a] pyrazine 1,4 dione and fatty acids especially hexadecanoic acid, were the main compounds with potential antifungal activity identified. Lactic acid bacteria inhibited the growth of aflatoxigenic Aspergilli, hereby reducing food intoxication.