Gut Microbiome Samples for PFAS Biotransformation
6:2 polyfluoroalkyl phosphate diester (6:2 diPAP) is a prevalent PFAS humans are exposed to regularly. Environmental microbes can biotransform 6:2 diPAP, and the human gut microbiome can biotransform a congener (8:2 monoPAP). Given the variable nature of the gut microbiome between individuals, we investigated potential variability in 6:2 diPAP biotransformation. Using six cohorts (A to F), the in vitro biotransformation of 6:2 diPAP by the human gut microbiome was examined. GC-MS, LC-MS/MS and 16S rRNA amplicon sequencing analyses were used to characterize biotransformation and the initial composition of microbial taxa. All cohorts converted 6:2 diPAP to 6:2 FTOH but differed in their downstream perfluoroalkyl acid (PFAA) profiles. Cohorts A and D had the highest 6:2 FTOH production whereas cohort F displayed the lowest 6:2 FTOH production. Cohort F was the only group with detectable intermediates, 6:2 fluorotelomer unsaturated acid (6:2 FTUCA) and 5:3 fluorotelomer saturated acid (5:3 FTCA), and the highest perfluorohexanoic acid (PFHxA) levels, suggesting a pathway favoring PFHxA formation. Cohort A exclusively produced PFPeA, while cohort D exhibited both PFHxA and PFPeA production. Microbial community analysis via 16s rRNA sequencing showed similar alpha diversity and variable beta diversity across cohorts. Key families associated with transformation patterns were identified. Bifidobacteriaceae positively correlated with 6:2 FTOH formation, while Erysipelotrichaceae exhibited a negative correlation, suggesting distinct roles in biotransformation. Furthermore, Aerococcaceae positively correlated with PFPeA production, while Anaerovoracaceae exhibited a negative correlation. The analysis confirmed the initial composition of each cohort's microbial community had a bearing on products stemming from 6:2 diPAP transformation, likely driven by rare microbial taxa. These findings underscore the complexity of microbe-mediated PFAS transformation and highlight the need for mechanistic studies that identify the genetic controls governing PFAS transformations in the gut microbiome.