Physico-chemical characterization of a new heteropolysaccharide produced by a native isolate of heterofermentative Lactobacillus sp CFR-2182

A heterofermentative Lactobacillus sp. CFR-2182 was isolated from dahi samples and it was found to produce 8.0 and 20.5 g/L heteropolysaccharide (HePS) in EPS medium (a simplified synthetic medium) and modified MRS broth, respectively, after 72 h at 30A degrees C. The total carbohydrate, reducing sugar and moisture contents of the purified HePS were 74, 10.6 and 2 g, respectively, per 100 g on dry weight basis. The HePS produced in EPS medium had glucose and mannose in 17:1 ratio. The HePS was non-gelling and non-film forming type. It was completely soluble in water and 1 N sodium hydroxide solution. Gel permeation chromatography and HPLC analysis indicated considerable heterogeneity of the HePS, having three fractions with molecular weights ranging from 3.3 x 10(4) to 1.32 x 10(6) Da. The enzymatic hydrolysis of the HePS with pullulanase and alpha-amylase [with alpha(1 -> 4) linkage] indicated the presence of alpha(1 -> 6) and traces of alpha(1 -> 4) linkages, respectively. NMR analysis of the EPS revealed unique chemical shifts.