Nature Reviews Microbiology 13, 691–706 (2015)

In the above article, there were two spelling errors. The credit line for Figure 2e should read: “Image of Deep Lake courtesy of M. Milnes, Australian Antarctic Division.” The acknowledgments should read: "The author is indebted to ... M. Milnes ... for providing images of Antarctic lakes..." These have now been corrected in the online version of the article. We apologize to the readers for any misunderstanding caused.