Abstract:

Four Lactobacilli stains were isolated and screened from traditional fermented dairy products dairy tofu popular in Inner Mongolia. According to phenotypic, physiological-biochemical and API tests, the strains were all identified as Lactobacillus plantarum and named C2, C8, C15, and C21, respectively. The negative staining method was used to observe their capsules, and the results indicated that except strain C2, all the others produced capsular polysaccharides and the capsules could be seen by using optical microscopy. The 48 h growth and exopolysaccharide-producing ability of the four strains were analyzed. It was found that all these strains exhibited a gradually increasing exopolysaccharides production during 48 h culture, and strain C21 produced the highest amount of exopolysaccharides.

Key words: exopolysaccharide, capsular polysaccharide, Inner Mongolia dairy tofu, Lactobacillus plantarum