A multi-variant investigation into the role of exopolysaccharide structures in Pseudomonas baetica

Kaycie B. Lanpher Microbial Diversity 2018 Abstract Pseudomonas baetica is a fish pathogen isolated in 2012 in the liver of wedge sole (López et al. 2012). One key feature of P. baetica is its ability to produce large amounts of extracellular polysaccharide (EPS) structures, which P. baetica may be utilizing to interact in various environments and for virulence as a pathogen. It is important that we understand the role of EPS in P. baetica as it is not yet well studied and will be of great importance for the fishing industry as wedge sole is being introduced more into aquaculture. The role of EPS was qualified by knocking out genes with transposon mutagenesis and selection for non-mucoid colonies. These non-mucoid mutants were then compared to the wild type strain of P. baetica for biofilm production, twitching motility, swarming motility, and swimming motility. The EPS production of the mutants and wild type were quantified with an alginate assay, and mutated genes were sequenced with arbitrarynested PCR. Overall, mutants were created with reduced EPS production and had a variety of changes in biofilm formation and motility types. The genes that were knocked out with the transposon mutagenesis were almost entirely involved with the cellular envelope molecular structure and could explain the variety of mutant phenotypes.