Department of Environmental Life Sciences
Division of Genetic Ecology

Environmental Microbiology 分野

Hisayuki Mitsui
キャンパス Katahira キャンパス
専攻分野 Microbiology, molecular biology
連絡先 022-217-5685

The symbiotic nitrogen fixation capabilities of root nodule bacteria (rhizobia) have been fostered through coevolution ever since leguminous plants first appeared on earth. When this was occurring, we believe that ancestral bacteria not only horizontally acquired new genes such as those involved in nitrogen fixation, but also modified their original genes to adapt to interactions with plants. Such modified genes appear to be involved in various functions such as cell surface properties and regulations of gene expression. My aim is to examine how each individual gene operates in the hope of being able to explain clearly in molecular terms the entire symbiosis capabilities of rhizobia.


1999 Associate Professor, Institute of Genetic Ecology, Tohoku University
2001 Associate Professor, Graduate School of Life Sciences, Tohoku University

著書・論文 Borjigin, N., K. Furukawa, Y. Shimoda, S. Tabata, S. Sato, S. Eda, K. Minamisawa, and H. Mitsui. 2011. Identification of Mesorhizobium loti genes relevant to symbiosis by using signature-tagged mutants. Microbes Environ. 26: 165-171
所属学会 Japan Society for Bioscience, Biotechnology and Agrochemistry, Society of Genome Microbiology, Japan, Japanese Society of Microbial Ecology

Symbiotic Gene Ecology (graduate students)
Joint Lecture on Ecology (graduate students)
Introduction to Life Science (all students)


I am currently identifying causal mutations and analyzing relevant gene functions using a number of rhizobial mutants that were isolated by focusing on unique phenotypes associated with plant interactions. For some genes whose mutations show symbiotic deficiency, it is difficult to estimate their function based only on amino acid sequence, but they generally have close homologs in non-symbiotic bacteria and eukaryotic organisms that can be utilized to infer function. Thus, I am conducting research expecting that analyses of the very peculiar biological phenomenon, symbiotic nitrogen fixation, might conversely lead to the understanding of universal molecular functions in living things.


Two years (or five) of graduate school go by quickly. Try to submerge yourself completely in your studies, in discussions, and in experiments. The experience you worked hard to acquire will absolutely enrich your life. Of course, it is essential to find that specific research theme worth submerging yourself in… (that’s the responsibility of the teacher).