Publication Date:
2019
Description:
〈p〉All known phototrophic metabolisms on Earth rely on one of three categories of energy-converting pigments: chlorophyll-〈i〉a〈/i〉 (rarely -〈i〉d〈/i〉), bacteriochlorophyll-〈i〉a〈/i〉 (rarely -〈i〉b〈/i〉), and retinal, which is the chromophore in rhodopsins. While the significance of chlorophylls in solar energy capture has been studied for decades, the contribution of retinal-based phototrophy to this process remains largely unexplored. We report the first vertical distributions of the three energy-converting pigments measured along a contrasting nutrient gradient through the Mediterranean Sea and the Atlantic Ocean. The highest rhodopsin concentrations were observed above the deep chlorophyll-〈i〉a〈/i〉 maxima, and their geographical distribution tended to be inversely related to that of chlorophyll-〈i〉a〈/i〉. We further show that proton-pumping proteorhodopsins potentially absorb as much light energy as chlorophyll-〈i〉a〈/i〉–based phototrophy and that this energy is sufficient to sustain bacterial basal metabolism. This suggests that proteorhodopsins are a major energy-transducing mechanism to harvest solar energy in the surface ocean.〈/p〉
Electronic ISSN:
2375-2548
Topics:
Natural Sciences in General
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