Validation of L-Lactic Acid Production Using Companilactobacillus farciminis KUJ 25-S for Sustainable Bio-Polylactic Acid Manufacturing

Companilactobacillus farciminis KUJ 25-S was isolated from fermented fish and identified using 16S rRNA gene sequencing with 30.0 g/L of L-LA (L-lactic acid), with 97% LA per sum of DL-LA. The characteristics of LA and its stereoisomers were confirmed using TLC, chiral-HPLC, and enzymatic techniques. Based on various conditions using liquid MRS broth (static condition, glucose 10%, NaCl 5%, 37 °C for 48 h), the highest growth and LA formation of the culture were at a low temperature (25 °C) and decreased at 37, 45, and 55 °C, respectively. The broth could grow and produce acid at an initial pH in the range 4–11, with a low initial pH of 4 promoting the highest LA formation. LA formation and growth were inversely proportional to the NaCl concentration in the 0.5–30% range. High glucose concentrations suppressed LA formation. The growth-promotion effect varied with glucose concentration (5–40%), with the optimum concentration for LA production being 20% glucose. On the other hand, if used in microoxic conditions, the absence of NaCl was more favorable to acidification than the addition of NaCl (5% NaCl). C. farciminis KUJ 25-S was proposed as a suitable method to produce L-LA based on using the appropriate line for further industrial use.