Abstract:

In this paper, lyophilized crude exopolysaccharides (EPS) were isolated by ethanol precipitation, deproteination
and dialysis from the cell-free culture supernatant of Bacillus amyloliquefaciens LPL061, demonstrated to be able to produce
high amounts of EPS, and fractionated into two peaks by anion exchange chromatography on DEAE-Sepharose fast flow
column, named as EPS1 and EPS2. The high yield and favorable proportion of EPS1 and EPS2 were obtained in optimized
medium (pH 7.0) containing 22 g/L sucrose and 18.4 g/L yeast extract when B. amyloliquefaciens LPL061 was cultivated
at 28 ℃ at 220 r/min for 24 h. The specific primers of EPS A, EPS B, EPS C, EPS E and EPS G were designed according
to the conservative gene sequences of B. amyloliquefaciens DSM 7 from GenBank (accession number: NC_014551.1). The
bioinformatic alignment and analysis from GeneBank database searching showed that the 5 genes had high homology with
the EPS biosynthetic genes of Bacillus amyloliquefaciens reported in NCBI, respectively. We acquired 5 gene sequences
such as repeat unit transporter (Wzx). Functional prediction analysis of open reading frames indicated that these 5 genes
were involved mainly in polysaccharide chain length determination, polymerization and export.

Key words: Bacillus amyloliquefaciens, exopolysaccharides, isolation and purification, gene cluster