Effect Of Ph And Salinity On Lactic Acid Production And Multiplication Of Plantaricin Plasmid Genes Of Lactobacillus Plantarum Coy 2906 Isolated From Virgin Coconut Oil

Lactic acid bacteria are assumed to act as a bio-preservative in virgin coconut oil (VCO) products, even under stress conditions. Lactobacillus plantarum COY 2906 and Lactobacillus sakei were isolated from VCO. L. plantarum COY 2906 showing greater ability than L. sakei to inhibit indicator bacteria and were selected for further study. Under saline stress conditions, L. plantarum COY 2906 did not inhibit E. coli K12 JM109 and showed greater inhibition of B. subtilis than of S. aureus JCM 20624. High saline content reduced lactic acid production, but the copy number of plnA, plnEF, plnN, plnJ and plnK genes associated with plantaricin, was not significantly changed. L. plantarum COY 2906 had its optimum anti-bacterial effect at pH 4.5 - 7.5, while alkaline conditions increased lactic acid production and reduced the multiplication of plantaricin plasmid genes.However, in acidic conditions, the number of plantaricin genes on the plasmid was multiplied. The genes: plnW, plnV, plnU, plnH, plnG, plnE, plnF, plnD, plnC, plnB, plnA, plnR, plnL, plnK, plnJ, plnM, plnN, plnO and plnP were found in the draft genome of L. plantarum COY 2906. This research clearly shows that lactic acid production and multiplication of plantaricin genes are affected by environmental salinity and pH.