The MGE contigs we collected probably
largely represent a mixture between
DNA of phages, plasmids, and transposable
elements, since all of these mobile
elements were found to be targeted by
CRISPR (Horvath and Barrangou 2010). To
specifically study phage genomes, we first
selected only MGE contigs sized 10 kb or
more (Reyes et al. 2010) since these are