title: Enhanced biofilm production by a toluene-degrading Rhodococcus observed after exposure to perfluoroalkyl acids.
abstract: This study focuses on interactions between aerobic soil-derived hydrocarbon degrading bacteria and a suite of perfluorocarboxylic acids and perfluoroalkylsulfonates that are found in aqueous film-forming foams used for fire suppression. No effect on toluene degradation rate or induction time was observed when active cells of Rhodococcus jostii strain RHA1 were exposed to toluene and a mixture of perfluoroalkyl acids (PFAAs) including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) at concentrations near the upper bounds of groundwater relevance (11 PFAAs at 10 mg/L each). However, exposure to aqueous PFAA concentrations above 2 mg/L (each) was associated with enhanced aggregation of bacterial cells and significant increases in extracellular polymeric substance production. Flocculation was only observed during exponential growth and not elicited when PFAAs were added to resting incubations; analogous flocculation was also observed in soil enrichments. Aggregation was accompanied by 2- to 3-fold upregulation of stress-associated genes, sigF3 and prmA, during growth of this Rhodococcus in the presence of PFAAs. These results suggest that biological responses, such as microbial stress and biofilm formation, could be more prominent than suppression of co-contaminant biodegradation in subsurface locations where poly- and perfluoroalkyl substances occur with hydrocarbon fuels.
authors: Hydrologic Science and Engineering Program and Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
authors: Tess S
authors: TS
authors: Weathers
authors: Hydrologic Science and Engineering Program and Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
authors: Christopher P
authors: CP
authors: Higgins
authors: Hydrologic Science and Engineering Program and Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
authors: Jonathan O
authors: JO
authors: Sharp
mesh_terms: D017738:Alkanesulfonic Acids / Q000378:metabolism / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development*; D002210:Caprylates / Q000378:metabolism / Q000494:pharmacology*; D005427:Flocculation; D005466:Fluorocarbons / Q000378:metabolism / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D060587:Groundwater / Q000737:chemistry; D012240:Rhodococcus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D012808:Sigma Factor / Q000235:genetics; D012988:Soil Microbiology; D013312:Stress, Physiological / Q000235:genetics; D014050:Toluene / Q000378:metabolism* / Q000494:pharmacology; D014874:Water Pollutants, Chemical
chemical_list: D017738:Alkanesulfonic Acids; D001426:Bacterial Proteins; D002210:Caprylates; C064971:FliA protein, Bacteria; D005466:Fluorocarbons; D012808:Sigma Factor; D014874:Water Pollutants, Chemical; D014050:Toluene; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid