In the ocean, which occupies a wide area of about 70% of the Earth’s surface area and a mean depth of 3800m, there exist special environments that are not found on land, such as high-temperature, low-temperature and high-pressure environments. Thus, a vast diversity of organisms, which possess the ability to adapt to various environments, live in it. Our laboratory is conducting research on marine photosynthetic microorganisms, such as microalgae and photosynthetic bacteria. With the microalgae culture collection kept at our laboratory, we explore various useful substance-producing strains to clarify their detailed production mechanisms and to improve their functions through genetic recombination.