Research Activities

Why are plants green? Are there any organisms that use green light as energy source? What color do the fish in the river look at? Do fish in the sea see a different color? What color does the esca of the angler fish glow?
My interest in color is the starting point, and our group is doing research the relationship between various organisms and light in the ocean.



Seawater sampling using an academic research vessel


A new light-utilization mechanisms by microbes (2008-) Which color of light are used as energy source by living organisms? For this question, it is common to answer that red and blue light are used by living organisms with chlorophyll for photosynthesis. In other words, the world full of green which is the color of unused light is recognized as a rich natural image. However, are there really few creatures who can use green light as energy in the highly competitive natural world? The answer is “NO”. Recently, it has become clear that a large number of microorganisms who can utilize green light as an energy source occur in marine ecosystem. Our group are doing research to elucidate the new light energy utilization mechanisms in marine environment.


Functional unknown photoreceptor proteins


Luminous bacteria (2002-) Bioluminescence is the production and emission of light by living organism. Bioluminescent organisms are commonly found at all depths of the ocean including the deep sea. There are more bioluminescent organisms in the ocean compared to those on land. Generally, light color emitted by marine organisms is recognized as blue-green in human eyes, and it is not considered to be diverse. However, because the color of light is a main factor that determines the distance of light penetration in seawater, even small differences in light color are considered important. We are interested in the “color of light” emitted by bioluminescent bacteria. And our group are doing research on their light utilization ecology and the evolutionary history of light emitting enzyme “luciferase”.


Characters by luminous bacteria



The anglerfish emits light by symbiosis of luminous bacteria in their esca


Taxonomic study of microorganisms (2005-) Most of the 4 billion-year history of organisms is created by microorganisms, and most of the biosphere on the earth are occupied only by microorganisms. Nevertheless, the current number of bacterial species (prokaryotes) is only about 10,000 species (about 1/100 of insects). Our group is also conducting research on taxonomy, such as isolation of novel bacterial species and proposal of their novel name.


Sampling at Setons Inland Sea

Literature

1) Hao Zhang, Susumu Yoshizawa, Ying Sun, Yongjie Huang, Xiao Chu, Jose M. Gonzalez, Jarone Pinhassi, Haiwei Luo. Repeated Evolutionary Transitions of Flavobacteria from Marine to Non-Marine Habitats. Environmental Microbiology, 21(2), 648-666. (2019).

2) Yu Nakajima, Takashi Tsukamoto, Yohei Kumagai, Yoshitoshi Ogura, Tetsuya Hayashi, Jaeho Song, Takashi Kikukawa, Makoto Demura, Kazuhiro Kogure, Yuki Sudo and Susumu Yoshizawa. Presence of a haloarchaeal halorhodopsin-like Cl- pump in marine bacteria. Microbes and Environments, 33, 89-97. (2018)

3) Yohei Kumagai, Susumu Yoshizawa, Yu Nakajima, Mai Watanabe, Tsukasa Fukunaga, Yoshitoshi Ogura, Tetsuya Hayashi, Kenshiro Oshima, Masahira Hattori, Masahiko Ikeuchi, Kazuhiro Kogure, Edward F. DeLong and Wataru Iwasaki. Solar-panel and parasol strategies shape the proteorhodopsin distribution pattern in marine Flavobacteriia. The ISME journal, 12, 1329-1343. (2018)

4) Daniel K. Olson, Susumu Yoshizawa, Dominique Boeuf, Wataru Iwasaki, Edward F. DeLong. Proteorhodopsin Variability and Distribution in the North Pacific Subtropical Gyre. The ISME journal, 12, 1047-1060. (2018)

5) Akiko Niho▽, Susumu Yoshizawa▽, Takashi Tsukamoto▽, Marie Kurihara, Shinya Tahara, Yu Nakajima, Misao Mizuno, Hikaru Kuramochi, Tahei Tahara, Yasuhisa Mizutani, and Yuki Sudo. Demonstration of a Light-Driven SO42- Transporter and Its Spectroscopic Characteristics. Journal of the American Chemical Society, 139 (12): 4376-4389. (2017)

6) Toshiaki Hosaka, Susumu Yoshizawa, Yu Nakajima, Noboru Ohsawa, Masakatsu Hato, Edward F. DeLong, Kazuhiro Kogure, Shigeyuki Yokoyama, Tomomi Kimura-Someya, Wataru Iwasaki and Mikako Shirouzu. Structural mechanism for light-driven transport by a new type of chloride ion pump, Nonlabens marinus rhodopsin-3. Journal of Biological Chemistry, 291(34), 17488-17495. (2016)

7) Yuki Sudo and Susumu Yoshizawa. Functional and Photochemical Characterization of a Light- Driven Proton Pump from the Gammaproteobacterium Pantoea vagans. Photochemistry and Photobiology, 92(3), 420-427. (2016)

8)Hideaki E. Kato, Keiichi Inoue, Rei Abe-Yoshizumi, Yoshitaka Kato, Hikaru Ono, Masae Konno, Shoko Hososhima, Toru Ishizuka, Mohammad Razuanul Hoque, Hirofumi Kunitomo, Jumpei Ito, Susumu Yoshizawa, Keitaro Yamashita, Mizuki Takemoto, Tomohiro Nishizawa, Reiya Taniguchi, Kazuhiro Kogure, Andres D. Maturana, Yuichi Iino, Hiromu Yawo, Ryuichiro Ishitani, Hideki Kandori and Osamu Nureki. Structural basis for Na+ transport mechanism by a light-driven Na+ pump. Nature, 521, 48-53. (2015)

9) Susumu Yoshizawa, Yohei Kumagai, Hana Kim, Yoshitoshi Ogura, Tetsuya Hayashi, Wataru Iwasaki, Edward F. DeLong and Kazuhiro Kogure. Functional characterization of flavobacteria rhodopsins reveals a unique class of light-driven chloride pump in bacteria. Proceedings of the National Academy of Sciences of the United States of America, 111(18), 6732-6737. (2014)

10) Keiichi Inoue, Hikaru Ono, Rei Abe-Yoshizumi, Susumu Yoshizawa, Hiroyasu Ito, Kazuhiro Kogure and Hideki Kandori. A light-driven sodium pump in marine bacteria. Nature Communications, 4, Article number: 1678. (2013)

11) Susumu Yoshizawa, Akira Kawanabe, Hiroyasu Ito, Hideki Kandori and Kazuhiro Kogure. Diversity and functional analysis of proteorhodopsin in marine Flavobacteria. Environmental Microbiology, 14, 1240-1248. (2012)

12) Susumu Yoshizawa, Minoru Wada, Kumiko Kita-Tsukamoto, Akira Yokota and Kazuhiro Kogure. Photobacterium aquimaris sp. nov., luminous marine bacteria isolated from seawater. International Journal of Systematic and Evolutionary Microbiology, 59, 1438-1442. (2009)

13) Susumu Yoshizawa, Minoru Wada, Kumiko Kita-Tsukamoto, Eiko Ikemoto, Akira Yokota and Kazuhiro Kogure. Vibrio azureus sp. nov., a luminous marine bacterium isolated from seawater. International Journal of Systematic and Evolutionary Microbiology, 59, 1645-1649. (2009)

Other Activities

THE JAPANESE SOCIETY OF MICROBIAL ECOLOGY
JAPAN GEOSCIENCE UNION
International Society for Microbial Ecology
Association for the Sciences of Limnology and Oceanography
American Society for Microbiology

Future Plan

What kind of place is a rich natural environment in a land ecosystem?
I think that most people imagine the environment where green plants are overgrown. This is because green light, which is difficult for plants to use, is reflected by the leaves and reaches our eyes. In other words, a rich place in nature is symbolized by “green” because there are almost no organisms that absorb green light. However, why are few organisms that use green light in an ecosystem with severe survival competition? We would like to understand the reason why there are few living organisms that use green light in land ecosystems by unraveling the evolutionary history of various light utilization mechanisms.

Messages to Students

Many people may think that microbial ecology is not a research field that contributes to understanding the global ecosystem. However, recent studies have shown that microorganisms play a major role in driving the “global biogeochemical cycle” and “solar energy flow through ecosystems”. Why, then, is microbial ecology research unfamiliar? It is because there are so many unsolved mysteries compared to other macro organisms. Let’s study and unravel the microbial ecology!

URL

http://genedynamics.aori.u-tokyo.ac.jp/en/