Hydrologic Science and Engineering Program and Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
Environ Sci Technol. 2015 May 5;49(9):5458-66. doi: 10.1021/es5060034. Epub 2015 Apr 17.
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.
本研究关注好氧土壤来源的烃类降解细菌与一系列全氟羧酸和全氟烷基磺酸盐之间的相互作用，这些物质存在于用于抑制火灾的水成膜泡沫中。当活性 Rhodococcus jostii 菌株 RHA1 细胞暴露于甲苯和全氟烷基酸（PFAAs）混合物（包括全氟辛酸（PFOA）和全氟辛烷磺酸（PFOS）），浓度接近地下水相关浓度上限（每种 11 种 PFAAs 为 10mg/L）时，甲苯降解速率或诱导时间没有受到影响。然而，暴露于水相 PFAA 浓度高于 2mg/L（每种）与细菌细胞的显著聚集和胞外聚合物产生的显著增加有关。仅在指数生长期观察到絮凝，而在静止孵育中添加 PFAAs 时不会引发絮凝；在土壤富集物中也观察到类似的絮凝。在 Rhodococcus 存在 PFAAs 的情况下生长时，聚集伴随着与应激相关的基因 sigF3 和 prmA 的 2-3 倍上调。这些结果表明，在多氟和全氟烷基物质与碳氢燃料共存的地下位置，生物反应（如微生物应激和生物膜形成）可能比共污染物生物降解的抑制更为突出。
