Increased cellulose production by heterologous expression of bcsA and B genes from Gluconacetobacterxylinus in E. coli Nissle 1917.

Abstract

Based on cellulose biosynthesis pathway of Gluconacetobacterxylinus BPR2001 and E. coli Nissle 1917, bcsA and bcsB genes have been selected and bioinformatics studies done to the analyses of nucleotide and amino acid sequence alignment, stability of RNA, protein, and promotor power. We amplify and clone bcsA, bcsB, and bcsAB genes of G. xylinus BPR2001 in Escherichiacoli Nissle 1917 under the inducible tac promoter. Our results of bioinformatics predictions demonstrate similar active site and three-dimensional structure of BcsA and BcsB proteins in two different bacteria. In addition, our data reveal that BcsA and BcsB proteins of E. coli have weaker promotor power, RNA secondary structure, and protein stability than that of the same proteins in G. xylinus. Some of the reasons of BcsAB protein selection from G. xylinus and its heterologous expression in E. coli is the noted points. Production of the related proteins visualized using SDS-PAGE. We find out that Congo red absorbance at 490nm has no significant difference in wild-type strain (E. coli Nissle 1917) compared to recombinants bcsA+ or bcsB+, but recombinant bcsAB+ could produce more cellulose than that of the wild-type strain. Furthermore, the measurement of cellulose dry weights of all samples confirms bacterial cellulose production enhancement in recombinant bcsAB+ (1.94gl-1). The FTIR analysis reveals that the crystallinity indices do not change significantly after over expressing each of genes.