Isolation of exopolysaccharide‐producing bacteria and yeasts from Tibetan kefir and characterisation of the exopolysaccharides

Abstract

Fifteen organisms were isolated from Tibetan kefir. Six of them were exopolysaccharide ( EPS )‐producing strains cultured in skim milk medium, which included two yeasts ( Kazachstania unispora ), one acetic acid bacterium ( Acetobacter okinawensis ) and three lactic acid bacteria ( Leuconostoc pseudomesenteroides ). The protein oxidative damage protection assay revealed that preincubation of exopolysaccharides (EPSs) could restore the levels of protein oxidation in a dose‐dependent manner. The SEM images indicated that there were great differences in the microstructures and surface morphologies among the EPS s. The GC analysis of the EPS s showed that all of the EPS s were composed of more than one kind of monosaccharide.