Evaluation of the antagonistic effect of some species of lactic acid bacteria isolated from fermented food against toxigenic Aspergillus flavus

Abstract

The presence of mycotoxigenic molds in food potentially poses hazards to healthy living and needs to be controlled. There is a greater risk that the resistance phenomenon will increase in the future due to the frequent use of antibiotics and preservatives, unlike biopreservation. Lactic acid bacteria are capable of producing secondary metabolites with antimicrobial properties. This study was conducted to evaluate the antagonistic effect of lactic acid bacteria isolates against toxigenic mold, Aspergillus flavus. Lactic acid bacteria were isolated from palm wine, ogi, and yogurt samples, and their antagonistic activity against toxigenic mold was investigated using the agar overlay method. Streptomyces spp. had the highest counts of 15.1×104 cfu/ml, while the least count of 2.0×104 cfu/ml from Lactobacillus plantarum was obtained. Pediococcus damnosus and Lactobacillus plantarum were present in both yogurt and palm wine samples. Similarly, Streptococcus spp. was identified in both yogurt and pap (ogi) samples. Aspergillus flavus was susceptible to half of the lactic acid bacterial isolates with varying degrees of inhibition. Total inhibition of toxigenic mold was observed on the control plate and plates inoculated with L. lactis, S. thermophilus, Leuconostoc mesenteriodes, P. damnosus, and L. bulgaricus. The antifungal activity of lactic acid bacteria suggests their biocontrol efficacy against A. flavus. Also, the antimicrobial properties of lactic acid bacteria can make them a suitable candidate in food preservation. Furthermore, this study can stand as a preliminary step in multistep research to investigate the anti-fungal and anti-aflatoxigenic potential of lactic acid bacteria from fermented foods against toxigenic A. flavus.