ABSTRACT

 Effect of different carbon and nitrogen sources on the growth of antimicrobial producing lactic acid bacteria in Nunu sold in Umuahai, Abia State were evaluated using standard microbiological and analytical methods. 16 lactic acid bacteria were isolated and identified based on their colony biochemical characteristics. The lactic acid bacteria isolated belong to the family Lactobacillus bulgaricus, Lactobacillus lactic, Lactobacillus plantarum, and Lactobacillus caesi. The percentage occurrence of lactic acid bacterial isolate from Nunu shows that Lactobacillus plantarum has the highest frequency occurrence of 6 (40) followed by Lactobacillus bulgaricus and Lactobacillus lactic 4(26.7%), while the lowest frequency occurrence were lactobacillus caesi 2(13.3%) and Lactobacillus lactics 3(20%) respectively. Agar well diffusion method was used to determine the antimicrobial activity of lactic acid bacteria against two pathogenic organisms, Escherichia coli, Staphylococcus aureus. Lactobacillus plantarum, Lactobacillus bulgaricus and lactobacillus casei had high antimicrobial activity after 24 hours of incubation. Lactobacillus plantarum showed anti-#, coli activity similar to that observed in this study, where the zones of inhibition were 10-15 mm in diameter. Antagonistic activity towards B. subtilis was also recorded ' at a similar level (10-15 mm). Also carbon sources of 5% and 10% sucrose, Glucose and soluble starch were used to check their different carbon sources on the isolates using the spectrophotometer. The- minimum inhibition zone was observed with medium containing urea as a nitrogen source followed by maltr extract for both organisms. Medium containing soybean meal as a nitrogen source showed inhibition zone diameter 27.42 for Lactobacillus bulgaricus while yeast extract showed highest inhibition zone for Lactobacillus lactis. Therefore it could be concluded that lactic acid bacteria is the predominate organism responsible for the fermentation of Nunu to give the fermented products. The effect ofthe different carbon and nitrogen sources is used to know the level or concentration of the growth of antimicrobial in the carbon sources. In conclusion, 5 percent (%) ofthe concentration should be in a medium to produce antimicrobial