Technical optimization of culture conditions for the production of exopolysaccharide (EPS) by Lactobacillus rhamnosus ATCC 9595

Microbial exopolysaccharide (EPS) is a biothickener that can be added to a wide variety of food products, where it serves as a viscosifying, stabilizing, emulsifying, and gelling agent. The objective of this study was to investigate the optimum conditions of pH, incubation temperature, and whey protein concentration (WPC) for EPS production by Lactobacillus rhamnosus ATCC 9595. We found that maximal EPS production was achieved at a pH of 5.5 and temperature of 37°C. At the same fermentation conditions, EPS production was affected by the addition of L. rhamnosus GG (a weak-EPS producer). After growth for 24 hr, total EPS production was 583±15.4 mg/L in the single culture system, and 865±22.6 mg/L in the coculture system with L. rhamnosus GG. Based on the presence of WPC, EPS production dramatically increased from 583±15.4 (under no WPC supplementation) to 1,011±14.7 mg/L (under supplementation with 1.0% WPC). These results suggest that WPC supplementation and the co-culture systems coupled with small portions of weak-EPS producing strain can play an important role in the enhancement of EPS production.