Searching Metagenomes for New Rhodopsins.

Most microbial groups have not been cultivated yet, and the only way to approach the enormous diversity of rhodopsins that they contain in a sensible timeframe is through the analysis of their genomes. High-throughput sequencing technologies have allowed the release of community genomics (metagenomics) of many habitats in the photic zones of the ocean and lakes. Already the harvest is impressive and included from the first bacterial rhodopsin (proteorhodopsin) to the recent discovery of heliorhodopsin by functional metagenomics. However, the search continues using bioinformatic or biochemical routes.