The Preliminary Isolation And Indentification Of Lactobacillus Casei ZJ-4 Producting Excellular Polysaccharide And The Cloning Of GalU

The lactic acid bacteria with high yield of exopolysaccharide were isolated from a traditional fermented food kimchi. By the way of morphological observation, as well as Gram stain,11 initial lactic acid bacteria strains were screened, which can product exopolysaccharides. One strain with high yield of exopolysaccharides was selected through fermentation, exopolysaccharide extraction and exopolysaccharide production determination of lactic acid bacteria, anbd the production was 771.97μgmL-1. The 16s rDNA sequence was amplified by PCR, its nucleotide sequence was determined and the homology and phylogenetic of the sequence was analysised after extracting the genome of lactobacillus with CTAB method, then the strain Lactobacillus casei ZJ-4 was preliminary determined. After designing the primers of galU sequence referring to the galU of Lactobacillus casei BL23(HM162415), the galUgene about 900bp was amplified by touch-down PCR with the genome as template. The PCR production was cloned to T vector and the homology was 98% comparing to the galU sequence of Lactobacillus casei BL23(HM162415).