Gut microbiota metabolize arsenolipids in a donor dependent way

Understanding the interplay between the gut microbiome and arsenolipids can help us manage the potential health risk of consuming seafood, but little is known about the bioconversion fate of arsenolipids in the gastrointestinal tract. We use an in vitro mucosal simulator of the human intestinal microbial ecosystem (M-SHIME) to mimic the digestive tract of four healthy donors during exposure to two arsenolipids (an arsenic fatty acid AsFA 362 or an arsenic hydrocarbon AsHC 332). The metabolites were analyzed by HPLC-mass spectrometry. The human gut bacteria accumulated arsenolipids in a donor-dependent way, with higher retention of AsHC 332. Colonic microbiota partly transformed both arsenolipids to their thioxo analogs, while AsFA 362 was additionally transformed into arsenic-containing fatty esters, arsenic-containing fatty alcohols, and arsenic-containing sterols. There was no significant difference in water-soluble arsenicals between arsenolipid treatments. The study shows that arsenolipids can be quickly biotransformed into several lipid-soluble arsenicals of unknown toxicity, which cannot be excluded when considering potential implications on human health.