Nexus of Soil Microbiomes,\nGenes, Classes of Carbon\nSubstrates, and Biotransformation of Fluorotelomer-Based Precursors

The unpredictable biodegradation of fluorotelomer (FT)-based\nper-\nand polyfluoroalkyl substances (PFAS) causes complicated risk management\nof PFAS-impacted sites. Here, we have successfully used redundancy\nanalysis to link FT-based precursor biodegradation to key microbes\nand genes of soil microbiomes shaped by different classes of carbon\nsources: alcohols (C2–C4), alkanes (C6 and C8), an aromatic\ncompound (phenol), or a hydrocarbon surfactant (cocamidopropyl betaine\n[CPB]). All the enrichments defluorinated fluorotelomer alcohols (<i>n</i>:2 FtOH; <i>n</i> = 4, 6, 8) effectively and\ngrew on 6:2 fluorotelomer sulfonate (6:2 FtS) as a sulfur source.\nThe butanol-enriched culture showed the highest defluorination extent\nfor FtOHs and 6:2 FtS due to the high microbial diversity and the\nabundance of desulfonating and defluorinating genes. The CPB-enriched\nculture accumulated more 5:3 fluorotelomer carboxylic acid, suggesting\nunique roles of Variovorax and Pseudomonas. Enhanced 6:2 FtOH defluorination was\nobserved due to a synergism between two enrichments with different\ncarbon source classes except for those with phenol- and CPB-enriched\ncultures. While the 6:2 fluorotelomer sulfonamidoalkyl betaine was\nnot degraded, trace levels of 6:2 fluorotelomer sulfonamidoalkyl amines\nwere detected. The identified species and genes involved in desulfonation,\ndefluorination, and carbon source metabolism are promising biomarkers\nfor assessing precursor degradation at the sites.