Yukino Mizutani Assistant Professor

Research overview

Working to Aid Local Industries by Illuminating and Reproducing the Mysteries of the Ariake Sea’s Organisms Researching the Bacteria and Viruses of the Ariake Sea’s Organisms
I have been studying bacteria that have symbiotic relations with bivalves since I was a university student. I am currently searching for microorganisms that co-exist with organisms that inhabit the Ariake Sea and illuminating their functions. I am directing my attention in particular to nori (edible seaweed) and bivalves, which are foodstuffs.

■ Discovery of New Viruses Present in Nori
To search for microscopic organisms on/inside nori and bivalves, I have collected the DNA or RNA storing genetic information that these microorganisms possess and have analyzed what kind of bacteria and viruses are present.

I consequently discovered that several species of bacteria with the same functions have settled on the nori and that these bacteria have genes for synthesizing vitamins, plant hormones, and other valuable substances. A newly discovered Mitovirus is present in all nori of the Ariake Sea, regardless of whether the nori is of the raw and still unprocessed variety or it is of the dried variety that we usually eat. Because the viruses that are classified as mitoviruses possess the attribute of replicating through vertical transmission from parent to offspring, this recently discovered virus is suggested to live inside the cells of the host nori for a long time, and it may be affecting the nori in some ways and creating a symbiotic relationship. I surmise that it may be possible to raise nori’s nutritional value, deepen its color, and elevate the product value of cultivated nori in other ways by analyzing the actions of these bacteria and viruses, selecting the microorganisms that have beneficial activities through culture tests, and reproducing the analyzed functions.

I am continuing my research into bivalves because I suspect that, among the bacteria that live in certain bivalves, there are those with metabolic functions that detoxify hydrogen sulfide, which is harmful to bivalves.

■ Making Full Use of an Environment Conducive to Research, and Giving Back to the Community
At Saga University, research has been conducted on the Ariake Sea. I can say that the research environment here is very conducive to studies because I can do research while exchanging information on not only living organisms but also on the preservation of the environment, culture, and multiple other fronts. In addition, the University’s Analytical Research Center for Experimental Sciences to which I belong has many specialized facilities, and the full use of these has been extremely important in the continuance of my research.
While I leverage this learning environment, I intend to further illuminate and reproduce the relationships between the microorganisms and their hosts that are peculiar to the Ariake Sea and apply the knowledge to the aquaculture industry.

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  Method for Researching Microorganisms That Have Symbiotic Relations with Nori

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  Predicted Functions of Bacteria That Have Symbiotic Relations with Bivalves