- Volume 30, Issue 1, 1980

A new genus of cellulolytic, gram-negative, nonsporeforming, anaerobic bacteria is described. The colonies produced by these bacteria on cellulose agar were round, clear, translucent, and cream-colored and had an undulate margin. Single cells of the bacterium were straight to slightly curved rods 0.5 to 0.8 µm wide by 4 to 10 µm long and were motile by means of a single flagellum located one-third of the distance from the end of the cell. Among the various substrates tested, only cellulose, cellobiose, and salicin were able to support growth. The major fermentation products of cellobiose or cellulose degradation were acetic acid, hydrogen, and carbon dioxide. The deoxyribonucleic acid base composition of the type species was 38 mol% guanine plus cytosine. The name Acetivibrio is proposed for this new genus, which is placed in the family Bacteroidaceae. The type species, Acetivibrio cellulolyticus sp. nov., is named on the basis of its cellulolytic activity. The type strain of A. cellulolyticus is CD2 (= NRC 2248).

A cellulolytic, gram-positive organism with a high (76.6 mol%) guanine plus cytosine content in its deoxyribonucleic acid is described as a new species, Cellulomonas cartae, because the original description and naming of this organism, as C. cartalyticum (sic), were in a patent and hence were neither effectively nor validly published. The taxonomic position of this organism as a member of the genus Cellulomonas is confirmed on the basis of biochemical and genetic characteristics. It is further shown that the new species differs from all other species of Cellulomonas described to date. The type strain of C. cartae is DSM 20106 (= ATCC 21681).

The carbon monoxide-utilizing hydrogen bacterium DSM 1083 (Carboxydobacterium strain Z-1062), the type strain of Seliberia carboxydohydrogena, was found to be a monotrichous, nonbudding, rarely screw-sculptured bacterium which did not convert lactose to 3-ketolactose and which was not pathogenic for tomatoes. Because of these properties and its strictly aerobic metabolism, it is proposed that this organism be transferred from the genus Seliberia to the genus Pseudomonas as Pseudomonas carboxydohydrogena (Sanjieva and Zavarzin) comb. nov. This species is distinctly different from other CO-utilizing pseudomonads with regard to guanosine plus cytosine content, substrate utilization spectrum, and extent of star formation.

Although Aessosporon salmonicolor was described with a homothallic life cycle, mating studies of strains of A. salmonicolor and Sporobolomyces spp. demonstrated a heterothallic life cycle typical of other basidiomycetous yeasts.

Two new species of the yeast genus Pichia were isolated from frass obtained from loblolly pines growing in Mississippi. The new taxa, designated Pichia amylophila and Pichia mississippiensis, are heterothallic, and Candida obtusa var. arabinosa proved to be a haploid member of the latter species. The species show interspecific mating, but ascospores from the crosses are infertile. The nuclear deoxyribonucleic acids from the species differ by 2 mol% in guanine plus cytosine content and exhibit low (25%) base sequence complementarity. Deoxyribonucleic acid relatedness was determined spectrophotometrically, and the methodology is given in detail.

Strains of Pichia ohmeri that form either spherical or hat-shaped ascospores comprise a well-defined assemblage, distinct in deoxyribonucleic acid base sequence and composition from other phenotypically similar yeasts. Thus, spore morphology, usually a stable systematic character, is not invariably reliable as a major taxonomic criterion among yeasts.