© TIM VERNON/SCIENCE SOURCE
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 ...
