Topic Area: 4g. SERDP & ESTCP Efforts on PFAS Biological Transformation and Remediation

Formatted Title:

Evaluation of Microbial Transformation of 6:2 FTCA and 6:2 FTOH Using Pure Microbial Cultures Capable of Expressing Monooxygenases

Background/Objectives:

A better understanding of site-specific biotransformation rate and extent of per-polyfluoroalkyl substances (PFAS) precursors is critical to PFAS site management, since many terminal biotransformation products are regulated drinking water and groundwater contaminants. It is hypothesized that periodic additions of hydrocarbon fuels, non-fluorinated surfactants, and water in firefighting training areas can stimulate enzymatic activity of indigenous microorganisms in PFAS source zones. We hypothesize that the in situ biotransformation of PFAS precursors is closely correlated with enzymatic activities stimulated by hydrocarbon fuels. Since the first step of hydrocarbon biodegradation is often initiated by monooxygenases, pure microbial cultures capable of expressing monooxygenases were first used to assess their potential of transforming 6:2 fluorotelomer alcohol (6:2 FTOH) and 6:2 fluorotelomer carboxylic acid (6:2 FTCA). These were chosen as model PFAS precursors because 6:2 FTOH is a commonly applied PFAS precursor, such as in food packaging, and 6:2 FTCA is a likely intermediate that can be further degraded to shorter chain perfluorocarboxylic acids (PFCAs).

Approach/Activities:

Six pure aerobic microbial strains that are known for their hydrocarbon degradation capabilities were assessed for their ability to transformation 6:2 FTCA. These six strains are: Rhodococcus opacus PD630, R. jostii RHA1, R. aetherivorans BCP1, R. rhodochrous ATCC 21198, Pseudomonas putida (oleovorans) GPo1, and P. putida KT2400. Four hydrocarbon substrates (propane, n-butane, n-hexane, and n-octane) and six non-hydrocarbon substrates (glucose, butyrate, hexanoate, octanol, lactate, ethylene glycol [a non-fluorinated chemical used in some AFFF formulations]) were used to assess how various growth substrates affect the extent of parent compound biotransformation and defluorination under growing and resting culture conditions. Activity based labeling (ABL) was used to evaluate monooxygenase expression levels supported by various growth substrates. Parent and transformation product quantization was assessed using liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS).

Yujie Men

Affiliation

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(Group 1, Poster Board #23) Evaluation of Microbial Transformation of 6:2 FTCA and 6:2 FTOH Using Pure Microbial Cultures Capable of Expressing Monooxygenases