Phytoplankton are the foundational primary producers sustaining marine ecosystems. Recent studies have revealed the widespread presence of microbial-type rhodopsins in phytoplankton—light receptors entirely distinct from photosynthesis. However, their physiological role remains poorly understood. In this study, we propose a novel hypothesis: microbial-type rhodopsins are localized on the outer membrane of chloroplasts, where they acidify the chloroplast interior using light energy, thereby enhancing carbon fixation.

Learn more about our findings here.