The human oral cavity is host to a complex microbial community estimated to comprise > 700 bacterial species, of which at least half are thought to be not yet cultivable in vitro. To investigate the plasmids present in this community, we used a transposon-aided capture system, which allowed the isolation of plasmids from human oral supra- and subgingival plaque samples. Thirty-two novel plasmids and a circular molecule that could be an integrase-generated circular intermediate were isolated.

Tetracycline resistance genes are common in the human oral cavity. However, a complete understanding of tetracycline resistance and the vectors responsible for spread of resistance requires that we understand the contribution of organisms that cannot be cultivated in the laboratory. To do this, metagenomic approaches have been applied and this has allowed the isolation of novel tetracycline resistance genes and mobile genetic elements.