Distribution of alginate genes in bacterial isolates from corroded metal surfaces

The distribution of alginate genes encoding biosynthesis of alginate was examined for bacterial isolates associated with corrosive biofilms recovered from source water, cooling lines, and reactor surfaces of a nuclear power plant. A total of 120 diverse Gram-positive and -negative isolates were obtained. Using DNA:DNA hybridization, 11 isolates were shown to contain sequences homologous to structural (algD, algG, alg-76) and/or regulatory (albB) alginate biosynthetic genes derived from an alginate-producing cystic fibrosis isolate of Pseudomonas aeruginosa (FRD1). Identification of isolates was accomplished by fatty acids methyl esters (FAME) analysis and the Biolog identification system. Nine of the twelve isolates were identified as various Pseudomonas spp., and two additional Gram-negative isolates were tentatively identified as Aeromonas veronii and Stenotrophomonas maltophilia. The remaining isolate was identified as a Gram-positive Bacillus pumilus. The results of the investigation extend current knowledge on the distribution of alginate biosynthetic genes in environmental isolates and permits the development of a more environmentally realistic model system to investigate the role of exopolymer production in biofilm formation and biocorrosion processes.