Expression of WANG_1291 gene of Lactobacillus kefiranofaciens ZW3

Abstract:

[Objective] The whole genome sequencing of Lactobacillus kefiranofaciens ZW3 is already known, it carries a 14.4 kb EPS (exopolysaccharides) gene cluster (WANG_1283 to WANG_1299) containing 17 EPS-related genes. In this study, we analyzed the expression quantity of 17 EPS genes in Lactobacillus kefiranofaciens ZW3 growth, and explored one expression quantity changed gene how to influence EPS yield. [Methods] Expression quantity of 17 EPS genes was analyzed by semi-quantitative RT-PCR technique; By constructing a recombinant strain of Lactococcus lactis containing an expression quantity changed gene, the EPS yield was compared between mutant strain and the wild strain. [Results] WANG_1284, WANG_1286, WANG_1287, WANG_1288, WANG_1290, WANG_1291, WANG_1292, WANG_1294, WANG_1296, WANG_1297, WANG_1298, WANG_1299 have the highest expression level at 50 h and 60 h when EPS was highly synthesized, suggesting that these genes play a role in the polymerization of polysaccharides. WANG_1291 was picked out from EPS genes to be further studied. This gene was inserted into plasmid pMG36e for the recombinant expression. The recombinant expression vectors were electroporated into Lactococcus lactis WH-C1. Assessing growth curves showed that the mutant strain and the wild strain have some differences. EPS yield of the recombinant was 2.1 times higher than that of the wild strain as analyzed by phenol-sulfuric acid method. [Conclusion] We provided evidence to show that WANG_1921 is a key gene to regulate Lactobacillus kefiranofaciens ZW3 EPS yield.

Key words:Lactobacillus kefiranofaciens ZW3, Exopolysaccharides, Semi-quantitative RT-PCR, Recombinant strains