Use of a bioluminescent reporter to monitor exopolysaccharide production by environmental bacteria from corroded metal surfaces

An alginic acid biosynthesis bioluminescent reporter plasmid, pUTK50, was transconjugated into environmental strains of Pseudomonas putida, Pseudomonas fluorescens, Stenotrophomonas maltophilia and Pseudomonas syringae. Bioluminescent transconjugates were selected from each strain for investigation of environmental stress factors promoting alginic acid exopolymer biosynthesis in developing biofilms. Environmental stimuli associated with increased levels of alginate synthesis, in a previously developed P. aeruginosa,/em> FRDl, were applied to the environmental strains. Increased salt concentrations and higher ratios of nitrate vs. ammonium ions as limited nitrogen source induced bioluminescence in FRDl and the environmental strains. However, for environmental strains of P. putida, P. fluorescens, P. syringae and S. maltophilia,/em>, polysaccharides were detected with low uronic acids content and different structural components. When tested within a biofilm, S. maltophilia 046 demonstrated exceptional adhesive and corrosive properties while alginic acid synthesis was not significantly high. In most of the environmental strains, periods of increased bioluminescence were induced by external stimuli, but exopolysaccharides other than alginic acid were expressed. It is hypothesized that the environmental strains have homologous but non-identical promoter sequences which are responsive to certain environmental stimuli and may control genes necessary for the production of alternative exopolysaccharides.