N-144. Examining Microbial Community Profiles from Natural Acid Rock Drainage at Peekaboo Gulch Colorado

S. DiFurio1, S. M. Pfiffner1, J. Kuntzman1, C. Webster2, J. Tapp2, A. Buchan3;
1Univ. of Tennessee, Ctr. for Environmental Microbiology, Knoxville, TN, 2Univ. of Tulsa, Ctr. for Applied Biogeosciences, Tulsa, OK, 3Univ. of Tennessee, Knoxville, TN.

This project examined factors that influence acid rock drainage at altitudes of over 11,000 feet in the Peekaboo Gulch drainage basin in the Sawatch Range, Colorado. The objective was to compare microbial communities in the aluminum-rich versus the iron-rich environments at the site. Outflows from acidic springs (pH=2.6) on Red Mountain formed the basis of this natural acid rock drainage. The acid drainage converged with South Fork Lake Creek (pH ≥ 7.0, prior to convergence) two miles down gradient. Sampling prior to 2007 focused on recovering microbes using BioTraps®. Microbial genera identified from these samples include Gallionella, Pseudomonas, and Actinobacter. Gallionella is the only genus typically associated with acid mine drainage. Microbial community analyses were conducted on BioTraps®, filtered water, biofilm, and sediment samples collected at Peekaboo Gulch during the 2007 post spring run-off conditions. Phospholipid results at four sampling sites have revealed membrane lipid profiles that varied based on sample type and chemical parameters (i.e. pH, metal concentration, etc.). Biomass estimates ranged from 7 to > 2.2 x 104 pmol/L for filtered water samples, from 2.8 x 102 to 2.0 x 104 pmol/g for sediments, from 1.1 - 4.6 x 104 pmol/g of BioTraps® beads, and 1.6 x 104 pmol/g for a biofilm sample. Respiratory potential was determined by analyzing the ubiquinone (UQ) and menaquinone (MK) compositions of the samples. Approximately half of the samples tested had quinones concentrations above the level of detection. The sediment and BioTraps® samples contain diverse profiles. The most prominent UQ was UQ8 while MK4, 5, and 6 were the most common MK. This research project provides a better understanding of the interactions between the microbiology and geochemistry at Peekaboo Gulch.