Isolation, Identification and Mode of action of Partially Purified Bacteriocins from Lactic Acid Bacteria in Fermented Cassava Grits

ABSTRACT

The study on the isolation, identification and mode of action of partially purified bacteriocin from lactic acid bacteria found in fermented cassava grits was carried out. Fermented cassava grits were collected from different garri processing plants and transported with cold box to the laboratory for analysis. The viable microbial count after the partially purified bacteriocin from the various lactic acid bacteria isolates were grown against the food borne bacteria (Staphylococcus aureus and Bacillus subtilis) ranged from 0.98 x 103 CFU/ml for partially purified bacteriocin from isolate 6 at 8 hrs to 9.2 x103 CFU/ml for isolate 3 at 24 hrs. Similar results were obtained against Bacillus subtilis with microbial counts that ranged from 1.02 x102 CFU/ml for isolate 3 at 8 hrs to 9.2 x 102 CFU/ml at 24 hrs. Isolates 6, 7, 10 and 11 were bactericidal to both Staphylococcus aureus and Bacillus subtilis while isolate 3 was bacteriostatic. The viable microbial count after the partially purified bacteriocin was grown against the foodborne bacteria (Escherichia coli and Salmonella typhi) ranged from 1.0 x102 CFU/ml for partially purified bacteriocin from isolate 3 at 8 hrs to 7.1 x 102 CFU/ml for partially purified bacteriocin from isolate 6 at 24 hours. The microbial count against Salmonella typhi ranged from 6.50 x 102 CFU/ml for isolate 6 at 8 hrs to 8.5 x 102 CFU/ml for isolate 7 at 24 hrs. Partially purified bacteriocins from isolates 3 and 7 were bacteriostatic while isolates 6, 10 and 11 were bactericidal to Escherichia coli and Salmonella typhi. This result showed that the partially purified bacteriocins were very efficacious in killing or inhibiting the growth of some foodborne pathogens which can be applied in biopreservation.