Bacteriocins From Lactic Acid Bacteria Associated With ‘Ogiri’, A Locally-Fermented Food Product:- Okonkwo Chinonye N

ABSTRACT Extraction and quantification of lactic acid bacteria bacterioccins isolated from “ogiri” a locally fermented food. This study was carried out to extract and quantify the lactic bacteriocins from “Ogiri” a locally fermented food. Total of ten (10) samples of Ogiri were purchased from local vendors who hawk the product around the Umuahia market. Serial dilution technique was employed in the inoculation of the Ogiri sample. The pure isolates were identified following a four-step analysis which are cultural examination, microscopic examination, biochemical reaction and sugar utilization test. This identified the LAB isolates to be Lactobacillusplantarum, bacillus subtilis, Bacillus licheniformis, Lactobacillus brevis, Lactobacillusfermentum, Escherichia coli and Staphylococcus aureus respectively. The lactic acid bacterial isolates were tested for antibacterial activity against Escherichia coli and Staphylococcus aureus. From this study, the highest activity was exhibited with a zone inhibition of 15m by L. plantarum against Escherichia coli, while the least activity was exhibited with a zone inhibition of 10mm by Bacillus subtilis and Lactobacillus brevis against Staphylococcus aureus and Escherichia coli respectively. The concentration of the crude bacteriocin produced by LAB tends to increase with increased concentration ofthe antimicrobial agents used. The highest concentration ofbacteriocin (0.22mg/l) was produced by Lacctobacillus plantarum at l.Omg/ml of the antimicrobial agent. Maximum activity of bacteriocin production was noted at pH 2 and 4, and temperatures 50°C and 40°C. bacteriocin production was strongly dependent on pH and temperature. The production of these bacteriocins was much higher at 50°C and 40°C, which suggested that the growth temperature also played an important role. This study concluded that the bacteriocin antibiotic produced by lactic acid bacterial isolates demonstrated inhibitor}' effects against bacterial indicator organisms.