Estimated number of proteorhodopsin (PR)-expressing bacteria in world's oceans

Value 1E+28 bacteria
Organism Biosphere
Reference Walter JM, Greenfield D, Bustamante C, Liphardt J. Light-powering Escherichia coli with proteorhodopsin. Proc Natl Acad Sci U S A. 2007 Feb 13 104(7):2408-12. p.2408 left column 2nd paragraphPubMed ID17277079
Primary Source Venter JC et al., Environmental genome shotgun sequencing of the Sargasso Sea. Science. 2004 Apr 2 304(5667):66-74. & Morris RM et al., SAR11 clade dominates ocean surface bacterioplankton communities. Nature. 2002 Dec 19-26 420(6917):806-10.PubMed ID15001713, 12490947
Comments "Aquatic ecosystems play a major role in the conversion of light energy into chemical energy, principally via chlorophyll-based photosynthesis (refs 1, 2). Other light-harvesting mechanisms include the light-driven proton pump bacteriorhodopsin, used by halobacteria living in salt ponds to supplement respiration (ref 3). In 2000, a novel light-driven proton pump, proteorhodopsin (PR), was discovered (ref 4). The world’s oceans contain an estimated 10^28 PR-expressing bacteria, placing them among the most prevalent organisms on Earth (primary sources)."
Entered by Uri M
ID 111062