Pseudomonas sp. Strain 273 Degrades Fluorinated Alkanes

Abstract

Fluorinated organic compounds have emerged as environmental constituents of concern. We demonstrate that the alkane degrader Pseudomonas sp. strain 273 utilizes terminally monofluorinated C7–C10 alkanes and 1,10-difluorodecane (DFD) as the sole carbon and energy sources in the presence of oxygen. Strain 273 degraded 1-fluorodecane (FD) (5.97 ± 0.22 mM, nominal) and DFD (5.62 ± 0.13 mM, nominal) within 7 days of incubation, and 92.7 ± 3.8 and 90.1 ± 1.9% of the theoretical maximum amounts of fluorine were recovered as inorganic fluoride, respectively. With n-decane, strain 273 attained (3.24 ± 0.14) × 107 cells per μmol of carbon consumed, while lower biomass yields of (2.48 ± 0.15) × 107 and (1.62 ± 0.23) × 107 cells were measured with FD or DFD as electron donors, respectively. The organism coupled decanol and decanoate oxidation to denitrification, but the utilization of (fluoro)­alkanes was strictly oxygen-dependent, presumably because the initial attack on the terminal carbon requires oxygen. Fluorohexanoate was detected as an intermediate in cultures grown with FD or DFD, suggesting that the initial attack on the fluoroalkanes can occur on the terminal methyl or fluoromethyl groups. The findings indicate that specialized bacteria such as Pseudomonas sp. strain 273 can break carbon–fluorine bonds most likely with oxygenolytic enzyme systems and that terminally monofluorinated alkanes are susceptible to microbial degradation. The findings have implications for the fate of components associated with aqueous film-forming foam (AFFF) mixtures.