||Sabehi, G., Massana, R., Bielawski, J.P., Rosenberg, M., Delong, E.F., and Béjà, O. (2003) Novel proteorhodopsin variants from the Mediterranean and Red Seas. Environ Microbiol 5: 842–849. & Rusch, D.B. et al. (2007) The sorcerer II global ocean sampling expedition: northwest atlantic through eastern tropical pacific. PLoS Biol 5: 398–431. & Campbell, B.J., Waidner, L.A., Cottrell, M.T., and Kirchman, D.L. (2008) Abundant proteorhodopsin genes in the North Atlantic Ocean. Environ Microbiol 10: 99–109. doi: 10.1111/j.1462-2920.2007.01436.x.PubMed ID14510837, 17355176, 18211270
||"Photoheterotrophic microbes include the proteorhodopsin
(PR)-based phototrophic (PRP) bacteria
and the aerobic anoxygenic phototrophic (AAP) bacteria.
After its initial discovery in a group of Gammaproteobacteria
(SAR86) (Béjà et al., 2000), PR has been found in
virtually every bacterial group in the ocean (Béjà and
Suzuki, 2008), most notably the ubiquitous clade of Alphaproteobacteria,
SAR11, and its cultivated representative,
Candidatus Pelagibacter ubique (Giovannoni et al.,
2005a). Proteorhodopsin is carried by 15% to > 70% of all
bacteria in surface waters, depending on the oceanic
region and detection method (primary sources)."