MICROBIAL COMMUNITY STRUCTURE OF THE VERMONT ASBESTOS GROUP MINE

Microbial communities are the foundation of all ecosystems, and cultivation-independent, metagenomic methodologies are providing new insights into the many roles microorganisms play in the biosphere. Humans have also demonstrated their ability to wreak havoc on ecosystems, and until recently investigations of human-induced perturbation have provided little understanding of microbial community dynamics. The overarching goal of this project is to expand our knowledge of these microbial community interactions using a combination of sequence-based and function-based methodologies.

The Vermont Asbestos Group (VAG) mine provides an experimental model to investigate resident microbial communities exposed simultaneously to multiple environmental stressors. The VAG Pit Pond and its Outlet present an alkaline aquatic environment, contaminated with asbestos-laden mine tailings and a variety of heavy metals. As no information is available on the microbial community structure of this aquatic ecosystem, our first goal was to characterize the taxonomic profile of its resident microorganisms.

We have confirmed the presence of cultivatable and non-cultivatable microorganisms in aquatic environments at the VAG mine. Sequencing a segment of the 16S rRNA gene of isolates cultured from the mine’s Pit Pond revealed the presence of 16 distinct genera belonging to 3 phyla and 11 families. The less severely impacted Pit Outlet revealed 11 genera belonging to 2 phyla and 7 families. Several of the Pit Pond cultivable bacteria have extremophilic characteristics and were originally isolated from extreme or contaminated environments. Microbial community diversity was also assessed using PhyloChip microarray, a culture-independent technology. This analysis revealed a more diverse set of taxa compared to the culturing methodology. The Pit Pond’s microarray profile consisted of 6 phyla and 14 families, and in the Pit Outlet, 12 families representing 4 phyla were identified. Approximately 30% of the identified operational taxonomic units were unique to each site.

Thus, our current data confirm the existence of a variety of distinct microorganisms in the VAG mine’s stressed environment. The work lays the foundation for study of microbial dynamics in ecological and geochemical processes of human-impacted environments.