Kluyveromyces nonfermentans sp nov., a new yeast species isolated from thedeep sea

Eleven strains of a new species of the genus Kluyveromyces, characterized a s having evanescent asci and Q-6 as the major ubiquinone, were isolated fro m sediments, a clam and a crab collected at depths of 1000-2000 m in Suruga Bay and Sagami Bay, Japan. A phylogenetic tree based on small-subunit (18S ) rRNA gene sequences placed these isolates into a cluster of Kluyveromyces . DNA complementarity and phylogenetic trees of internal transcribed spacer (ITS) regions and 5.8S rRNA genes showed that the isolates are closely rel ated to Kluyveromyces aestuarii, but that these two species are genetically distinct. The isolates are described as Kluyveromyces nonfermentans sp. no v. Because this species lacks the fermentative ability considered to be an important criterion for the genus Kluyveromyces, the definition of the genu s has been emended. The type strain of K. nonfermentans is strain SY-33(T) (= JCM 10232(T)).