“Delicious Seafood” on Our Table.

  Plankton and bacteria play crucial roles in the marine environment, forming the foundation of the marine food chain. It is widely known that these primary producers obtain the energy they need from organic matter produced through photosynthesis in the photic zone. However, in 2000, a new photoreceptor gene called “proteorhodopsin” was discovered in the genomic fragment of the SAR86 bacterial group. Subsequent research revealed that the proteorhodopsin gene is widely distributed among marine bacteria and archaea. Proteorhodopsin functions as a light-driven proton pump, capturing light energy and using it to move protons across the cell membrane. This proton gradient is then converted into chemical energy. Currently, it is estimated that more than half of the prokaryotes inhabiting the ocean’s surface layer possess proteorhodopsin. Therefore, estimating the amount of solar energy entering the marine ecosystem through proteorhodopsin is of significant importance.

  Our group is focused on elucidating the sequence diversity and spatiotemporal fluctuations of proteorhodopsin through metagenome and metatranscriptome analyses. We are also investigating the evolution of the proteorhodopsin gene and its physiological role using large-scale comparative genomics and culture experiments.