Abstract: This study evaluated the effects of the exopolysaccharides (EPS) produced by Lactobacillus helveticus MB2-1 and its purified components on the growth characteristics of probiotics in order to gain further insights into the probiotic function of the EPS of L. helveticus MB2-1. The optical density (OD600 nm) values of ten probiotics and two pernicious strains continuously cultured in a medium with EPS or EPS-2, the most abundant component separated and purified from EPS, as the sole carbon source were determined. The residual amounts of total EPS and the amounts of short-chain fatty acids (SCFA) produced in 10 probiotics during 48 h of culture were measured by high performance liquid chromatography (HPLC). The results showed that the 10 probiotics could grow and reproduce at different rates in the medium with EPS or EPS-2 as the sole carbon source. Among them, Enterococcus faecium MN-1grown in EPS showed a maximum growth rate of 0.225 h-1 at 11.56 h. The growth of the two pernicious strains was inhibited to a certain extent compared with normal glucose medium. Lactic acid was produced in larger amounts than other SCFA. L. paracasei was the most efficient producer of lactic acid, and at 48 h of fermentation, the lactic acid concentration reached 57.6 mmol/L, which increased by 121.7% as compared with 26.1 mmol/L at the beginning of fermentation. This study demonstrated that the EPS derived from L. helveticus MB2-1 is a good carbon source for the ten probiotics and can be used as potential prebiotics to regulate intestinal health in humans and animals.

Key words: Lactobacillus helveticus MB2-1, exopolysaccharides, growth curve, short-chain fatty acids, probiotic function