The purpose of this study was to identify and quantify breakdown products of the environmental contaminants 6:2 fluorotelomer sulfonamide alkyl betaine (FTAB) and 6:2 fluorotelomer sulfonate (FTSA), when added as the sole-sulfur source to cultures of the soil bacterium, Gordonia sp. NB4-1Y. FTAB is used in aqueous film forming firefighting foams and it is known that FTSA will appear, upon the initial degradation of FTAB, in soil, aquatic ecosystems, and ground water with suspected adverse health effects in animals and humans. The majority of existing data on FTAB biodegradation is from analysis of contaminated soil and water samples, and metabolism by mixed microbial communities in sewage treatment plants, rather than from studies involving pure cultures. In an effort to understand the fundamental biochemical processes driving bacterial FTAB and FTSA metabolism, sulfur-limited pure cultures of NB4-1Y were analyzed for both volatile and water-soluble breakdown products using a Dionex Ultimate 3000 UHPLC chain coupled to a Thermo Q-Exactive Orbitrap mass spectrometer over 7 days. Over 168 h, 99.97 % of 60-µM FTSA was degraded into eleven major breakdown products, with a mol % recovery of 88.22, while 70.42 % of 60-µM FTAB was degraded into ten major breakdown products, with a mol % recovery of 84.65. The products detected indicate that NB4-1Y may be using two different approaches for FTSA desulfonation, with approximately 55 mol % of breakdown products being assigned to a major pathway that begins with the conversion of FTSA to 5:2-FT-ketone, with 5:2-FT-ketone being the major product at 43.62 mol %. The minor pathway, hypothesized to begin with conversion of FTSA to 5:3-FTCA, accounted for less than 1.0 mol % of products after 168-hrs of incubation. FTSA is a proposed intermediate of FTAB breakdown by NB4-1Y, but was not detected, possibly due to rapid utilization under sulfur-limiting conditions. As with FTSA breakdown, 20.07 % of FTAB products were assigned to the major pathway, while less than 1.0 mol % were assigned to the minor pathway. Future research will involve isolating enzymes involved in FTAB and FTSA metabolism, verifying their function in vitro, and designing molecular tools for monitoring their metabolism in the environment by diverse microbial communities.
