Genome Sequence of Pseudomonas stutzeri 273 and Identification of the Exopolysaccharide EPS273 Biosynthesis Locus.

273 is a marine bacterium producing exopolysaccharide 273 (EPS273) with high anti-biofilm activity against PAO1. Here, the complete genome of 273 was sequenced and the genome contained a circular 5.03 Mb chromosome. With extensive analysis of the genome, a genetic locus containing 18 genes was predicted to be involved in the biosynthesis of EPS273. In order to confirm this prediction, two adjacent genes ( and ) encoding glycosyltransferases and one gene () encoding tyrosine protein kinase within the genetic locus were deleted and biosynthesis of EPS273 was checked in parallel. The molecular weight profile of EPS purified from the mutant Δ was obviously different from that purified from wild-type 273, while the corresponding EPS was hardly detected from the mutant Δ, which indicated the involvement of the proposed 18-gene cluster in the biosynthesis of EPS273. Moreover, the mutant Δ had the biofilm formed earlier compared with the wild type, and the mutant Δ almost completely lost the ability of biofilm formation. Therefore, EPS273 might facilitate the biofilm formation for its producing strain 273 while inhibiting the biofilm formation of PAO1. This study can contribute to better understanding of the biosynthesis of EPS273 and disclose the biological function of EPS273 for its producing strain 273.