BACTERIAL ADAPTATION TO AN ANTHROPOGENICALLY-ALTERED, SERPENTINE-RICH AQUATIC ENVIRONMENT

Bacterial communities are affected when ecosystems are altered by mining activities. At the Vermont Asbestos Group Mine in Eden and Lowell, Vermont, an estimated 29 million tons of serpentine and metal-enriched tailings have buried 1540 acres, suppressing vegetation and creating an alkaline, nutrient-deficient aquatic environment. Leaching of trace elements and chrysotile has further altered the environment by elevating concentrations of magnesium, arsenic, and asbestos fibers; fish and macroinvertebrate communities are impacted. We have begun an assessment of the aquatic microbial communities and have isolated over 100 Operational Taxonomic Units from mine water samples, many possessing extremophilic and pathogenic properties. As a first step toward identifying microbial adaptation to a serpentine landscape, we have implemented a series of experiments to explicate physiological changes in three mine isolates.

Sequencing a segment of the 16S rRNA gene identified bacteria from mine water samples. Three isolates, Aeromonas salmonicida, Serratia fonticola, and Pseudomonas protegens, having BLAST percent pairwise and percent identical sites greater than 99.5%, and their American Type Culture Collection reference strains were used in a series of growth studies. Growth rates were compared in low and high nutrient media to elucidate evidence of physiological change in mine isolates.

A. salmonicida and P.protegens revealed distinctly different growth rates when compared to their reference strains, suggesting physiological change had occurred. S. fonticola paralleled growth with its reference strain and did not demonstrate physiological change. Our findings suggest microbial adaptation to a serpentine-rich, anthropogenically-altered environment.