The In Vitro Control Of Post Harvest Yam Decay Using Bacteriocin Extracted From Lactic Acid Bacteria Isolated From Ugba:- Ugwu Bonaventure U

ABSTRACT

 Attempt was made at in vitro control of post harvest yam pathogens using bacteriocin extracted from Lactic acid bacteria isolated from “ugba” a femented legume seed food. Seven fungi species were isolated including Yeasts, Aspergillus, Penicillium, Rhizopus, Mucor, Fusarium and Botryodiplodia with varying extent of prevalence. Yeast, Aspergillus and Rhizopus had 100% occurance each while Penicillium, Fusarium and Botryodiplodiarecorded 80% occurance each and mucor had 40%. Results if pathogenicity test {in-vivo) confirmed Aspergillus, Fusarium, Penicillium and Botryodiplodia species to be pathogenic while the other isolates did not cause significant rots in fresh healthy tubers. Two Lactic Acid Bacteria, Lactobacillusfermenti and Lactobacillus plantarum were isolated and identified in the “ugba” sample and crude bacteriocin extract from them were used in the in vitro control tests. Results obtained from the tests show variation in their antifungal activities against the yam pathogen. Lactobacillusfermenti crude bacteriocin extract caused inhibitions in the range of 9.67mm {Fusarium) to 12.00mm {Penicillium) while the extracts of L. plantarum caused inhibition zone with diameter range of 9.67mm {Fusarium) to 12.67mm {Penicillium and Botryodiplodia). The antifungal activities of the crude extract of the LAB isolate was not significantly different (P<0.05) against the isolates except against Aspergillus species. Also the activities of the extract were below that of a standard antifungal drug, Mancozade which recorded inhibition ranges of 19.33mm {Botryodiplodia) to 23.67mm {Aspergillus). In general, the demonstrated antifungal activities of the crude bacteriocin extracts against the pathogens was seen as an indication of the potentials of the extracts for use in the control of the post harvest yam pathogens. The need for enhancement of their activity was noted and purification was suggested as an option to achieve this