(256f) Optimization of Growth Media and Functionality Characterization of New Potential Probiotic L. Salivarius, Isolated from Human Milk

Probiotics are viable non-pathogenic microorganisms that colonize the intestine, modify the intestinal microflora and their metabolic activities positively affect the health of the host. Nowadays many research activities have focused on the benefits of administering live microbial feed supplements to restore the normal intestinal microbial balance in human gut. To date the increasing interests in some of these breast milk lactobacilli such as L. gasseri, L. salivarius and L. rhamnosus. Generally, commensal bacteria, isolated from human milk, has been identified for their potential use as bacteriotherapeutic agents in preventing neonatal and maternal breast infections which caused by pathogenic bacteria. Therefore, in this present work, the studies of cell growth of L. salivarius in different media and cultivation conditions in shake flask and bioreactor have been conducted. The medium which yielded highest cell mass and lowest lactic acid in shake flask then was optimized using different meat peptone, glucose and yeast extract concentration. This is purposely to accelerate the cultivations performance of L. salivarius when subjected to large scale production in bioreactor under controlled and uncontrolled pH conditions. The optimized medium for L salivarius biomass production was compositions of (g L^-1): glucose, 20.0, yeast extract, 20 and meat peptone, 35. This specific growth rate of bacteria reached 0.179 h^-1 (max biomass 5.71 g L^-1)in shake flask, and 0.249 h^-1 (maxim biomass 7.57 gL^-1 ) in controlled pH bioreactor. L. salivarius exhibited higher tolerance to simulated gastric juice and pH as well and can withstand lower pH in certain limit. When cell incubated at low pH of 4, 3, 2 and 1, cell viability was 65%,63%,38.8% and 22.9%, respectively. The number of viable cells was reduced from 12.44 to 12.21 (1.84% inhibition), 12.33 to 12.29 (0.32% inhibitions), 10.51 to 10.16 (3.33%), 10.72 to 10.23 (4.57%), when incubated in 0.5%,1%, 2%,3% and 4% bile salt solution after 2 hours for L. salivarius. This bacteria was susceptible to ampicillin, tetracycline, rifampicin and erythromycin. Although, this potential probiotic bacteria L. salivarius resistance to gentamycin and streptomycin. In conclusion, L. salivarius , new isolated from human milk, has a big potential application as a probiotic bacteria for human consumption.