A comprehensive survey of integron-associated genes present in metagenomes

摘要

Integrons are machineries that enables transfer of genetic material between DNA molecules [1, 2]. Through site-specific recombination, integrons have the ability to incise, excise and re-organize genes into, out of, and within a host genome [3–5]. Integrons are estimated to be present in at least 6% of the bacterial genomes [6] and can be located either on chromosomes, as in e.g. Vibrio ssp. and Xanthomonas ssp., or on conjugative elements, as is common for in pathogens such as Escherichia coli and Salmonella enterica [7, 8]. Since integrons enable incorporation of a wide range of genes, they have been suggested to play a major role in the adaptation and evolution of many forms of bacteria [9–11]. Integrons present in pathogenic bacteria often carry antibiotic resistance genes, which enable the bacteria to survive antibiotic treatment. Similarly, chromosomal integrons present on Vibrio ssp. maintain virulence factors, such as genes encoding for toxins, which enable bacteria to gain advantages when colonizing different environments and hosts [7, 12, 13]. However, despite their central role in adaptation, the functional repertoire of integron-associated genes is far from fully characterized.