Kerry Grens, The Scientist, 22 December 2016 http://www.the-scientist.com/?articles.view/articleNo/47845/title/New-CRISPR-Cas-Enzymes-Discovered/
In a new Nature (https://www.ncbi.nlm.nih.gov/pubmed/28005056) letter Burstein et. al. report the discovery of the first Cas9 identified in archaea and two small Cas enzymes from bacteria. The new enzymes were discovered through a metagenomics approach by collecting samples from various field sites, extracting the DNA, and reconstructing the genomes which has resulted in a terabase-scale collection of genomic information. Once putative genes were identified each Cas analog was expressed in E. coli to confirm its ability to block genetic information introduced into the cell.