S. Miyake, U. Stingl
John Wiley & Sons, Ltd: Chichester, (2011)
The membrane‐bound protein Proteorhodopsin (PR) is a simple light‐dependent proton pump. The single gene that encodes PR was
detected in 2000 on genomic fragments of heterotrophic marine bacteria. Over the following years, researchers realised that
the majority of bacteria in the photic zone (where light is present) of nearly all oceanic water bodies possess this protein.
The high abundance of closely related PR genes in only distantly related bacteria is very likely due to frequent lateral gene
transfer. Experiments with PR‐containing pure cultures did not show uniform results on improved growth upon illumination,
indicating a functional diversity that probably depends on environmental nutrient conditions. In most cases, PR will help
bacteria to produce additional energy without the need of oxidising organic carbon. This energy can be used to grow better,
move faster or survive longer during starvation periods.