Yeasts Isolated from Deep-sea
Takahiko NAGAHAMA*a, Makiko HAMAMOTOb, Takashi NAKASEa, and Koki HORIKOSHIa
a The DEEPSTAR group, Japan Marine Science and Technology Center, 2-15 Natsushima-cho, Yokosuka 237, Japan
b Japan Collection of Microorganisms, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 251-01, Japan
One hundred twenty-three strains, including 43 organic solvents-tolerant strains (1), of yeasts were isolated from muds or clams collected in several places of deep-sea. The number of yeasts isolated decreased accompanied by the increase of the depth of the sea where the samples were taken. However, the ratio of basidiomycetous yeasts increased accompanied by the depth. Among the basidomycetous yeasts isolated, Rhodotorulas were dominant and occupies 88.9% of the isolates. On the other hand, ascomycetous yeasts were taxonomically diverse and these genera were shown as follows: Candida, Debaryomyces, Kluyveromyces, Pichia, Saccharomyces, and Williopsis.
Eleven strains of ascomycetous isolates from mud at several different places in deep-sea formed evanescent asci containing 1 to 4 oval or round ascospores with smooth walls, and were assumed to represent a species of Kluyveromyces, though they lacked fermentative ability. The isolates had the same major ubiquinone, Q-6, as the other Kluyveromyces species have. Phylogenetic analysis of 18S rRNA genes showed that these strains were located in the cluster of Kluyverornyces but clearly differentiated from the other species of the genus. These eleven strains were completely identical in the sequences of 18S rRNA gene, 5.8S rRNA gene and Internal transcribed Spacer (ITS) region though they showed some differences in the carbon assimilation patterns. Apparently, these strains represent a new species of the genus Kluyveromyces.
1. Fukumaki, T., Inoue, A., Moriya, K., and Horikoshi, K. (1994) Biosci. Biotech. Biochem., 58 (10), 1784-1788.
