Open AccessEpsA is an essential gene in exopolysaccharide production in L actobacillus johnsonii FI9785
Author(s) -
Dertli Enes,
Mayer Melinda J.,
Colquhoun Ian J.,
Narbad Arjan
Publication year - 2016
Publication title -
microbial biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.287
H-Index - 74
ISSN - 1751-7915
DOI - 10.1111/1751-7915.12314
Subject(s) - complementation , gene cluster , gene , biochemistry , regulator , strain (injury) , chemistry , gene expression , biosynthesis , biology , phenotype , anatomy
Summary L actobacillus johnsonii FI9785 has an eps gene cluster which is required for the biosynthesis of homopolymeric exopolysaccharides ( EPS )‐1 and heteropolymeric EPS ‐2 as a capsular layer. The first gene of the cluster, epsA , is the putative transcriptional regulator. In this study we showed the crucial role of epsA in EPS biosynthesis by demonstrating that deletion of epsA resulted in complete loss of both EPS ‐1 and EPS ‐2 on the cell surface. Plasmid complementation of the epsA gene fully restored EPS production, as confirmed by transmission electron microscopy and nuclear magnetic resonance ( NMR ) analysis. Furthermore, this complementation resulted in a twofold increase in the expression levels of this gene, which almost doubled amounts of EPS production in comparison with the wild‐type strain. Analysis of EPS by NMR showed an increased ratio of the heteropolysaccharide to homopolysaccharide in the complemented strain and allowed identification of the acetylated residue in EPS ‐2 as the (1,4)‐linked βGlc p unit, with the acetyl group located at O ‐6. These findings indicate that epsA is a positive regulator of EPS production and that EPS production can be manipulated by altering its expression.