Bacteria and Humans Have Been Swapping DNA for Millennia

Bacteria inhabit most tissues in the human body, and genes from some of these microbes have made their way to the human genome. Could this genetic transfer contribute to diseases such as cancer?

Written byKelly Robinson and Julie Dunning Hotopp

| 9 min read

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Before we understood that DNA was the genetic code, scientists knew that bacteria transferred it between cells. In 1928, 25 years before the structure of DNA was solved, British bacteriologist Frederick Griffith demonstrated that live, nonvirulent bacteria could transform into virulent microbes after being incubated with a heat-killed virulent strain. Fifteen years later, a trio of researchers at the Rockefeller Institute for Medical Research (now Rockefeller University), Oswald Avery, Colin MacLeod, and Maclyn McCarty, demonstrated that this transformation was mediated by DNA. Even dead bacteria, it seemed, could share their genes.

Almost all bacterial genomes show evidence of past LGT events, and the phenomenon is known to have profound effects on microbial biology.

This DNA-sharing process, known as horizontal or lateral gene transfer (LGT), is ...

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