Characterization of a xylanase-producing Cellvibrio mixtus strain J3-8 and its genome analysis

Abstract

Cellvibrio mixtus strain J<inf>3</inf>-8 is a gram-negative, xylanase-producing aerobic soil bacterium isolated from giant snails in Singapore. It is able to produce up to 10.1 U ml-1 of xylanase, which is comparable to xylanase production from known bacterial and fungal strains. Genome sequence analysis of strain J3-8 reveals that the assembled draft genome contains 5,171,890 bp with a G + C content of 46.66%, while open reading frame (ORF) annotations indicate a high density of genes encoding glycoside hydrolase (GH) families involved in (hemi)cellulose hydrolysis. On the basis of 15 identified putative xylanolytic genes, one metabolic pathway in strain J<inf>3</inf>-8 is constructed for utilization of xylan. In addition, a 1,083 bp xylanase gene from strain J<inf>3</inf>-8 represents a new member of GH<inf>11</inf> family. This gene is verified to be novel via phylogenetic analysis. To utilize this novel gene for hydrolysis of xylan to xylose, it is expressed in recombinant E. coli and characterized for its hydrolytic activity. This study shows that strain J<inf>3</inf>-8 is a potential candidate for hydrolysis of lignocellulosic materials.