Physiological approach to extracellular polysaccharide production by Lactobacillus rhamnosus strain C83

Extracellular polysaccharide production was studied by growing strain C83 of Lactobacillus rhamnosus in a chemically defined medium containing various carbon sources (glucose, fructose, mannose or maltose) at different concentrations. Mannose or a combination of glucose + fructose were by far the most efficient carbon sources. An optimization of growth medium composition led to an improvement in both growth and EPS production. When the strain nas cultured at a lower temperature the EPS production increased. A temperature shift, at the end of the exponential growth phase, did not enhance the EPS production. The EPS synthesis by strain C83 was growth-related. The isolated slime had a sugar composition, as shown by three different methods, of glucose and galactose with a ratio of 1:1.