LONDON: Scientists claim to have found the first direct evidence that bacteria in the ocean can harvest light energy from sunlight for survival, thanks to a unique photoprotein.
"It was long thought that phytoplankton were the only organisms in the sea that could harvest the energy from sunlight forgrowth," said lead scientist Jarone Pinhassi of Linnaeus University in Sweden .
These microscopic planktonic organisms carry out the same chlorophyll driven photosynthesis process as green plants on land, say scientists.
In 2000, American scientists discovered that many marine bacteria contain a gene in their genome that encodes a new kind of light-harvesting pigment: proteorhodopsin. Proteorhodopsin is related to the pigment in the retina that enables human vision in less intense light. Now, a decade later, the first direct evidence for the functioning of proteorhodopsin in native marine bacteria is presented,based on mutational analysis in a marine bacterium.
The research also shows that proteorhodopsin-mediated phototrophy(the process of acquiringenergy from light) allows marine bacteria to better survive periods of starvation in an often nutrient-depleted ocean.The activity of these bacteria play a crucial role in the global carbon cycle by determining oceanic production of CO? through respiration and determining how thefluxes of energy that are fixed by photosynthesis are channelled through marine food chains, say the scientists.
"Bacteria in the surface ocean are swimming in a sea of light, and it may not be all that surprising that evolution has favoured microorganisms that can use this abundant energy source," said Pinhassi.
The findings have been published in the PLoS Biology journal.
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