Abstract
Lactobacillus kefiranofaciens is known to produce an exopolysaccharide (kefiran) that is either excreted in the growth medium or attaches to the cell wall. In order to achieve high exopolysaccharide production, we devel oped a new rice hydrolyzate (RH) medium using rice starch hydrolyzate as the carbon source and rice protein hydrolyzate as the peptone source. In this study, three fermentation experiments using RH medium, PYG10 medium and PYL10 medium were carried out, respectively. The highest amount of exopolysaccharide production was obtained from the culture grown in RH medium. Among the three various media compositions compared, rice protein hydrolyzate in the RH medium demonstrated the ability to significantly enhance exopolysaccharide production by L. kefiranofaciens. In addition, the cultivation of L. kefiranofaciens in a 500l tank was also experimentally conducted, and the maximum yield of exopolysaccharide from the RH culture was 2.5 g/l after a seven-day culture period at pH 5.0 and 33°C. This result indicates that it is possible to produce exopolysaccharide (OSKC) at the level required for large-scale industrial production through the cultivation of L. kefiranofaciens in RH medium.
