EFFECTS OF EXTERNAL STIMULI ON ENVIRONMENTAL BACTERIAL STRAINS HARBORING AN ALGD-LUX BIOLUMINESCENT REPORTER PLASMID FOR THE STUDY OF CORROSIVE BIOFILMS

An alginic acid biosynthesis bioluminescent reporter plasmid, pUTK50, was transconjugated into environmental strains of Pseudomonas putida, Pseudomonas fluorescens, and Stenotrophomonas maltophilia. Bioluminesc ent transconjugates were selected from each strain for investigation o f environmental stress factors that promote alginic acid exopolymer bi osynthesis in developing biofilms. Environmental stimuli associated wi th increased levels of alginate synthesis, in a previously developed o rganism, P. aeruginosa FRD1, were applied to the environmental strains . Increased salt concentrations and higher ratios of nitrate vs ammoni um ions as the limiting nitrogen source induced bioluminescence in FRD 1 and the environmental strains. However, for environmental strains of P. putida, P. fluorescens and S. maltophilia, polysaccharides were de tected with low uronic acids content and different structural componen ts. When tested within a biofilm, S. maltophilia 046 demonstrated exce ptional adhesive and corrosive properties while alginic acid synthesis was not high. In most of the environmental strains, periods of increa sed bioluminescence were induced by external stimuli, but exopolysacch arides other than alginic acid were expressed. It is hypothesized that the environmental strains have homologous but nonidentical promoter s equences which are responsive to certain environmental stimuli and may control genes necessary for the production of alternative exopolysacc harides.