Tuesday, November 14, 2006

Effect of Carbon Substrates on Aerobic Biotransformation of 8:2 Fluorotelomer Alcohol in Soil Microcosm and Pure Bacterial Cultures.

Jinxia Liu, Linda S. Lee, Cindy Nakatsu, and Loring F. Nies. Purdue Univ, 915 W State St, Agronomy Dept, West Lafayette, IN 47907

Telomer-based polymers and surfactants are suspected to degrade into perfluorinated acids (PFCA) during disposal, thus potentially contributing to the global contamination of PFOA in humans, wide life and environmental compartments. Elucidating the biodegradability and biotransformation mechanisms of fluorotelomer alcohols (FTOHs) in soils is an important step towards understanding the fate of these polymers and surfactants in the environment particularly in wastewater treatment plants, land-applied biosolids and landfills. This study focused on assessing the microbial biotransformation mechanism of 8:2 fluorotelomer alcohol (CF3-(CF2)7-(CH­2)2-OH, FTOH) in the presence of different organic co-substrates (ethanol, octanol and 1,4-dioxane). In soil microcosm studies, transformation of 8:2 FTOH occurred rapidly in presence of 1,4-dioxane and ethanol, but not with octanol. Transformation of 8:2 FTOH did not start until after octanol was completely oxidized. Seven metabolites were confirmed and quantified with authentic standards using liquid chromatography tandem mass spectrometry. The types and relative abundance of seven metabolites were independent of the specific carbon substrate added. Results suggest that the biotransformation of 8:2 FTOH is not via a co-oxidization process as what was previously speculated. It also implies that octanol degraders in soil may be partially responsible for 8:2 FTOH biotransformation, but that octanol is the preferred carbon source. Additional experiments were conducted with octanol-utilizing bacteria enriched from soil. Two primary octanol-utilizing bacteria were isolated. Isolates degraded 8:2 FTOH, but again preferably utilized octanol as a sole carbon source. Once the octanol was depleted, 8:2 FTOH began to transform rapidly. There was no discernible biomass growth in response to 8:2 FTOH degradation. Bacterial isolates were identified by sequencing the 16S rRNA gene. The bacteria identified are common soil bacteria that have been found to degrade aliphatic polycarbonates; therefore, biodegradability of FTOHs in soils is very likely to be ubiquitous.