Transposon-aided capture (TRACA) of plasmids from the human gut.

This article focuses on the isolation and characterization of plasmids from the human gut microbiota using the transposon-aided capture method (TRACA), a culture-independent technique that enables plasmid extraction from uncultured intestinal microbes. Fecal samples from two healthy volunteers yielded 15 plasmids, 13 of which were fully sequenced; 12 showed high similarity to known small plasmids primarily from Enterobacteriaceae, while one plasmid, named pMRPHD, appeared novel. The novel plasmid pMRPHD contains mobilization elements (oriT and oriV) and encodes a type II restriction–modification system involving DNA cytosine methyltransferase and a Ban I restriction enzyme, suggesting potential roles in plasmid stability and bacterial adaptation. These findings demonstrate TRACA's utility in exploring gut microbial plasmids and provide a foundation for further functional and ecological studies of plasmids in the gut microbiota.