Antifungal Activity of Lactic Acid Bacteria against Molds Isolated from Corn and Fermented Corn Paste

摘要

A total of 336 molds were isolated from dried corn, soaked corn and fermented corn paste. The macroscopic and microscopic studies of fungal growth in the following identification media, grouped all the 336 molds into 21 strains. The strains belonged mainly to 4 fungal genera: Aspergillus, Fusarium, Penicillium and Rhizopus. In addition, the aflatoxinogenic strains were dominant and were mostly isolated from Maroua (63 strains of Aspergillus flavus). Moreover, the antifungal activity of 53 Lactic acid bacteria (LAB) isolated from the samples was performed against 21 fungal strains. After a screening test, 06 were selected for their potent antifungal activity and were identified as Lactobacillus brevis (2 isolates), Lactobacillus buchneri (1 isolate), Lactobacillus cellobiosus (1 isolate) and Lactobacillus fermentum (2 isolates). During the antifungal tests in solid medium, most of the LAB inhibited the growth of molds but Lactobacillus brevis G25 (80 ± 0.5 mm) and Lactobacillus cellobiosus (82 ± 0.1 mm) had the greatest antifungal activities after 48 hours against Aspergillus carbonarius G23 and Aspergillus carbonarius G24. However, the antifungal activity was more efficient in liquid medium and Lactobacillus brevis G11 and Lactobacillus fermentum N33 totally inhibited the growth of the 21 molds tested in liquid medium. Thus organic acids were identified as substances responsible for the antifungal activity of the LAB. These results show the possibility of exploiting some of these LABs as starters to fight against spoilage molds in fermented corn paste.