Nat. Biotechnol. 36, 242–248 (2018); published online 19 February 2018; corrected after print 8 March 2018

In the version of this article initially published, the references in the reference list were in the wrong order; the references have been renumbered as follows: 3 as 2; 5 as 3; 6 as 8; 7 as 9; 8 as 11; 9 as 6; 10 as 12; 11 as 5; 12 as 13; 13 as 7; 16 as 10; and no. 2, “Hoch, J.A. & Losick, R. Panspermia, spores and the Bacillus subtilis genome. Nature 390, 237–238 (1997),” has been deleted. In addition, on p.242, end of paragraph 2, the citation in “experiments7” has been deleted. The errors have been corrected in the HTML and PDF versions of the article.