Division of International Affairs, Headquaters, National Institute of Technology, Tokyo, Japan; Department of Creative Engineering, National Institute of Technology, Kitakyushu, Japan
Mais Maree
Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
Toshihiko Nagamura
Department of Creative Engineering, National Institute of Technology, Kitakyushu, Japan
Akihiro Koga
Department of Creative Engineering, National Institute of Technology, Kitakyushu, Japan
Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan; Division of Microbiology and Infectious Diseases, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
Soichi Furukawa
Department of Food Bioscience and Biotechnology, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
Kenji Tanaka
Department of Biological and Environmental Chemistry, School of Humanity-Oriented Science and Engineering, Kindai University, Iizuka, Japan
A diversity of prokaryotes currently exhibit multicellularity with different generation mechanisms in a variety of contexts of ecology on Earth. In the present study, we report a new type of multicellular bacterium, HS-3, isolated from an underground stream. HS-3 self-organizes its filamentous cells into a layer-structured colony with the properties of a nematic liquid crystal. After maturation, the colony starts to form a semi-closed sphere accommodating clusters of coccobacillus daughter cells and selectively releases them upon contact with water. This is the first report that shows that a liquid-crystal status of cells can support the prokaryotic multicellular behavior. Importantly, the observed behavior of HS-3 suggests that the recurrent intermittent exposure of colonies to water flow in the cave might have been the ecological context that cultivated the evolutionary transition from unicellular to multicellular life. This is the new extant model that underpins theories regarding a role of ecological context in the emergence of multicellularity.
