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 30�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 9 104 to 1.32 9 106 Da. The enzymatic hydrolysis of
the HePS with pullulanase and a-amylase [with a(1?4)
linkage] indicated the presence of a(1?6) and traces of
a(1?4) linkages, respectively. NMR analysis of the EPS
revealed unique chemical shifts.