This week in
Science, researchers led by genome sequencing pioneer
Craig Venter report engineering a bacterium to have the smallest genome - and the fewest genes - of any freely living organism. Known as
Syn 3.0, the new organism has a genome whittled down to the bare essentials needed to survive and reproduce, just 473 genes. However, the function of 149 of Syn 3.0's 473 genes remain unknown.
As Syn 3.0's name suggests, it’s not the first synthetic life made by Venter. In 2010, Venter's team reported that they had synthesized the sole chromosome of
Mycoplasma mycoides - a bacterium with a relatively small genome - and transplanted it into a separate mycoplasma called
M. capricolum, from which they had previously extracted the DNA. After several false starts, they showed that the synthetic microbe booted up and synthesized proteins normally made by
M. mycoides rather than
M. capricolum. Still, other than adding a bit of watermark DNA, the researchers left the genetic material in their initial synthetic organism, Syn 1.0, unchanged from the parent.
With a total of 531,000 bases, Syn 3.0's genome isn’t much smaller than that of
M. genitalium, with 600,000 bases. But
M. genitalium grows so slowly that a population of cells can take weeks to double. Syn 3.0, by contrast, has a doubling time of 3 hours, suggesting that it thrives with its slimmed down genome. For now, however, Syn 3.0 reigns as the world’s new lightweight champ.
Source: http://www.sciencemag.org/news/2016/03/synthetic-microbe-lives-less-500-genes
