We gratefully acknowledge Tuomas Tenkanen (Finnzymes Oy) for providing DNA polymerases and for helpful technical discussions, Todd DeSantis (Lawrence Berkeley National Laboratory) and Phil Hugenholtz (DOE Joint Genome Institute) for assistance with 16S rRNA gene sequence databases, Kirk Harris (University of Colorado) and Joe Felsenstein (University of Washington) for help with constructing phylogenetic trees, and members of the Ruvkun laboratory (Massachusetts General Hospital) and the Handelsman laboratory (University of Wisconsin) for helpful discussion of this work. We also acknowledge the SETG team, especially George Church (Harvard Medical School) and Maria Zuber (Massachusetts Institute of Technology), for thoughtful discussions regarding this research and the Massachusetts Institute of Technology Center for Space Research for guidance.