北太平洋海域の海水から分離した酵母に関する研究

Abstract

A large number of samples, water for the study of microorganisms, were obtained on the occasions of the cruises of the “Ryofu Maru” and “Oshoro Maru” in the North Pacific extending to the Bering Sea, Aleutian region, east off the Japan Proper Island, south off the Japan Proper Island and East China Sea during the years 1959-60. A total of 801 samples which were taken from various depths down to about 3000meters were placed to this study. For isolation of marine yeasts the medium adopted was ZOBELL 2216-E, and the classification of yeasts was made according to the method of LODDER and VAN RIJ. In this paper are reported species of yeasts identified, their distribution with geographical areas and depths, and the results of experiments on their growth in relation to the salinity, pH value and temperature conditions. One hundred forty-four isolates comprised of species belonging to genera, Rhodotorula, Torulopsis, Cryptococcus, Saccharomyces, Sporoboromyces or Candida. Among them species belonging to Rhodotorula were most abundantly and widely distributed. The number of isolated was larger than elsewhere at the layers of 0m, 100-150m and 750m depths, while it was very small below 1000meters. There was no difference of growth between marine and terrestrial strain at low saline media (0-5%), but the marine species grew better than in terrestrial strains at high saline media (7-9%). The marine species did not grow better than in terrestrial strains at low pH value (pH 2), but no difference of growth between them at high pH value (pH 4-12). There was a tendency to inhibition of growth by high temperature (37°C.) in marine strains, compared with terrestrial strains.