In vitro Inhibition of Fusarium by Lactic Acid Bacteria (LAB): Implication of Yam Disease Control for Economic Growth in Nigeria

Yam is an important crop in Nigeria, where it is produced both as food and cash crop. Fusarium rots of yam are among the most important postharvest pathogens of yam worldwide, causing a lot of postharvest losses in stored yam tubers. Lactic acid bacteria (LAB) lower the pH and create an environment that is unfavorable to pathogens and spoilage organisms. In vitro inhibition of fusarium spp by LAB was investigated; mono-culture and multi-culture were used. The inhibition tests were carried out with pure cultures of LAB and fusarium spp. The pure culture of actively growing Fusarium was used to inoculate Potato Dextrose Agar medium aseptically and then incubated at room temperature for 72h. The diameter of the growing Fusarium was measured, after which less than a loop full of actively growing (18-24 h) LAB isolates were used to inoculate the medium containing the growing Fusarium at a known distance in the same plate. The whole set up was incubated at 300C and inhibition zones on Fusarium by the LAB were observed 24 hourly for 96h. The tests were carried out for mono-culture and multi-culture in triplicate. The inhibition zone ranged from 43 to 100% in mono-culture plate and multi-culture plate ranged from 40 to 113%. The slightly larger inhibition in the multi-culture plate may be due to much pressure on the Fusarium. Hence LAB may be used to control rot caused by Fusariumin in stored yam, which can improve yam tuber storage for better economic growth.