Enriching fluorotelomer carboxylic acids-degrading consortia from sludges and soils

Fluorotelomer carboxylic acids (FTCAs) has drawn increasing attention due to their prevalent occurrence, high toxicity, and bioaccumulating effects. In this study, microbial consortia with sustainable FTCA removal abilities were enriched and characterized from two activated sludges and five soils when no external carbon sources were supplemented. After four generations of enrichment, stable 6:2 FTCA and 5:3 FTCA biodegradation were achieved, reaching 0.72-0.98 and 0.53-1.05 μM/day, respectively. Coupling with 6:2 FTCA biotransformation, fluoride release co-occurred, conducive to approximate 0.19 fluoride per 6:2 FTCA molecule that was biodegraded. In contrast, minimal free fluoride was detected in 5:3 FTCA-amended consortia, indicating the dominance of "non-fluoride releasing pathways". Microbial community analysis revealed the dominance of 13 genera across all consortia. Among them, 3 genera, including Hyphomicrobium, Methylorubrum, and Achromobacter, were found more enriched in consortia amended with 6:2 FTCA than those with 5:3 FTCA from an identical inoculation source, suggesting their involvement in biodefluorination. This study uncovered that microbial consortia can degrade FTCAs without the supplementation of external carbon sources, though with low biotransformation and biodefluorination rates. Further research is underscored to investigate the involved biotransformation pathways and biodefluorination mechanisms, as well as effects of external carbon sources.