Antifungal activity of bacteriocins of lactic acid bacteria from some nigerian fermented foods

Abstract

This study was conducted to evaluate the antifungal activity of bacteriocins of lactic acid bacteria from some Nigerian fermented foods (Eko, Fufu, Iru and Ogi). Screening of 25 bacteriocin-producing Lactic Acid Bacteria (LAB) isolated from Eko, Fufu, Iru and Ogi against three spoilage fungi (Penicillium citrinum, Aspergillus niger and A. flavus) associated with stored fermented foods revealed that 68% of the isolates possessed antifungal activity. About 36% of those which showed a high fungicidal activity were isolated from sorghum Ogi. Penicillium citrinum was the most sensitive while Lactobacillus brevis SGI was the most active of all the LAB strains. Spore germination and mycelia growth of P. citrinum was inhibited in the presence of both the LAB cells and their neutralized, cell-free culture supernatants (CFNS) using different bioassays. Generally, the results of all the bioassays were comparable. However, the antifungal activity of the LAB strains was easily detectable in liquid media and more pronounced on spore germination of the fungus than on its mycelia growth. The inhibitory effect of the bacteriocins on spore germination of P. citrinum ranged from 2.44 to 85.36% in Lactobacillus casei FF1 andL. brevis SGI, respectively. This study demonstrated that germination of fungal spores and fungal growth were significantly reduced by the LAB cells and/or their cell-free filtrates, thus indicating the propensity of the use of these antifungal substances in bio-control. © 2010 Academic Journals Inc.