The evolutionary affinities among several morphologically and physiologically similar species of the ascogenous yeast genus Hansenula were studied by a technique which involved genome comparisons in combination with nuclear deoxyribonucleic acid base composition determinations. The results revealed a new member of the genus Hansenula that was recovered five times in 1968 from slime exudates of Populus trichocarpa (cottonwood trees) in British Columbia and Alaska. This new species is named Hansenula populi because of its specific habitat in exudates of cottonwood trees. H. populi is homothallic and occurs naturally in the haploid state. Conjugation between vegetative cells precedes sporulation, and up to four hat-shaped spores are produced in zygotes. The spores are liberated from the asci soon after formation. H. populi resembles Hansenula nonfermentans and Hansenula dryadoides but differs from these species in habitat, guanine-plus-cytosine content of the nuclear deoxyribonucleic acid, maximum growth temperature, and ability to assimilate several carbon compounds. The type strain of H. populi is UCD-FS&T 68-628C (= CBS 8094 = ATCC 48773).
BernardiG.,
FauresM.,
PipernoG.,
SlonimskiP.P.1970; Mitochondrial DNAs from respiratory-sufficient and cytoplasmic respiratory-deficient mutants of yeast. J. Mol. Biol 48:23–43
BurtonK.1956; The conditions and mechanism of the diphenylamine reaction for the colorimetric estimation of deoxyribonucleic acid. Biochem. J 62:315–323
PhaffH. J.,
MillerM. W.,
YoneyamaM.,
SonedaM.1972; A comparative study of the yeast florae associated with trees on the Japanese Islands and on the west coast of North America. 759–774Terui G.Fermentation technology today Society of Fermentation Technology; Osaka, Japan:
PriceC. W.,
FusonG. B.,
PhaffH.J.1978; Genome comparison in yeast systematics: delimitation of species within the genera Schwanniomyces, Saccharomyces, Debaryomyces, and Pichia. Microbiol. Rev 42:161–193
SchildkrautC. L.,
MarmurJ.,
DotyP.1962; Determination of the base composition of deoxyribonucleic acid from its buoyant density in CsCl. J. Mol. Biol 4: 430–433
ScottD. B.,
van der WaltJ. P. .
1971; Hansenula dryadoides sp. n., a new species from South African insect sources. Antonie van Leeuwenhoek J. Microbiol. Serol 37:171–175
van der WaltJ. P.1970; Criteria and methods used in classification. 34–113LodderJ. .
The yeasts—a taxonomic study North-Holland Publishing Co; Amster-dam: