M. Shifrine

THE ASSOCIATION OF YEASTS WITH CERTAIN BARK BEETLES

There is now a vast literature describing various aspects of the rela? tionship between insects and microorganisms (see e.g. Steinhaus, 1946). Taxonomic studies on yeasts associated with bark beetles began when Beck (1922) described a new species of yeast, Endomyces bisporus, which she isolated repeatedly from the galleries of Ips typographus attacking spruce in Austria. Siemaszko (1939) also noted this yeast associated with Ips typographus in Picea excelsa in Poland. StellingDekker (1931) renamed this yeast Endomycopsis bispora, because it forms blastospores besides true mycelium. It was finally renamed Hansenula beckii (Beck) by Wickerham (1951) since it utilizes nitrate-ion as a single source of nitrogen, a typical characteristic for species of Hansenula. Lodder and van Rij (1952), however, feel that the yeast should be maintained in Endomycopsis in spite of the fact that it is nitrate positive, because of its abundant production of true mycelium. It may be well to point out that all studies on this yeast were done with the original isolate of Beck. The only other report in the literature, which describes the occurrence of this yeast in Ips typographus, is a paper by Grosmann (1930). Her insect material was collected from two well separated areas in central Germany. Beside E. bisporus, she found various wood staining fungi and another yeast producing hatshaped spores (2-4 per ascus) which dehisce early. This yeast did not produce mycelium or pseudomycelium. The possibility was considered that this yeast might belong to Hansenula. A third type did not pro? duce spores. Grosmann also found yeasts in the intestinal tract of adults and larvae and in fresh excreta. The view was expressed that the yeasts are not essential for the growth of the insects, but merely live in association with them as commensals. Rumbold (1931) and Leach, Orr and Christensen (1934) also noted the regular occurrence of yeasts and yeast-like organisms in association with bark beetles and bluestaining fungi. Somewhat later Holst (1936) showed that a new spe? cies of yeast, which was named Zygosaccharomyces pini, could be iso? lated regularly from phloem galleries and the bark beetles Dendroctonus and Ips from various parts of the United States. This yeast, lacking

The taxonomy of yeasts isolated fromDrosophila in the Yosemite region of California

SummaryA survey was made of the yeasts occurring in the intestinal tract of wild species ofDrosophila occurring in the Yosemite Region of California. Two hundred and forty one yeasts, representing 42 species and varieties, were identified. Each isolate was obtained from a different fly. Almost half of the isolates belong toSaccharomyces. The most common species in this genus wereS. montanus (36 isolates),S. veronae (30 isolates),S. cerevisiae var.tetrasporus (22 isolates) andS. drosophilarum (13 isolates). Further species are listed in Table 1.Zygosaccharomyces fermentati Naganishi was shown to be a distinct species and not a synonym ofS. cerevisiae. In order to avoid confusion with another yeast of the same name, it has been proposed to change the nameZ. fermentati toS. montanus Naganishi. Two new species ofSaccharomyces were described,S. wickerhamii andS. kluyveri. S. mangini var.tetrasporus has been renamedS. cerevisiae var.tetrasporus. A non-cellobiose attacking strain ofS. drosophilarum has been designated tentativelyS. drosophilarum var.acellobiosa. A new species of the genusPichia was described asP. xylosa. Saccharomyces pastori andSaccharomyces pini were transferred to the genusPichia on the basis of arguments given in the preceding paper. A new species ofTrichosporon was described asTr. aculeatum on the basis of the presence of characteristic needlelike cells. Common species besides those mentioned inSaccharomyces wereHansenula angusta (19),Kloeckera apiculata (15),Kl. magna (13), andTorulopsis stellata (10). Other genera represented wereHanseniaspora, Cryptococus, Rhodotorula, Candida andOospora. Evidence was obtained that many species of imperfect genera consist of distinctly different physiological types.

On the isolation, ecology and taxonomy ofSaccharomycopsis guttulata

SummaryA simple procedure is described for the isolation of pure cultures ofSaccharomycopsis guttulata from rabbit feces. Sporulation occurs best on YM agar at 18°C., whereas vegetative growth takes place only between 35° and 40°C. On solid media growth occurs only in an atmosphere saturated with water vapor. Vegetative cells are diploid and uninucleate. Upon reduction division two to four nuclei could be observed after staining with Azure A, resulting in asci with one to four spores. Viability of the spores is low. In mass cultures, spores in some asci germinated after conjugation in pairs and in some, single spores germinated. During germination an exosporium is evident. A tentative life cycle has been proposed.S. guttulata is short lived at room temperature or above. However, at 5°C. a vegetative culture remains viable for about 2 months and a sporulating culture for at least six months. The ecology and natural cycle ofS. guttulata have been described and related to the habit of coprophagy in rabbits. A complete description ofS. guttulata is given, including its morphological and physiological properties. The genusSaccharomycopsis is considered to be valid.

On the cell wall composition ofSaccharomycopsis guttulata

SummaryCells ofSaccharomycopsis guttulata were ruptured by sonic oscillation and the resulting cell walls were purified by washing and centrifugation. The walls contained 43.7% carbohydrate (expressed as glucose), 39.6% protein and a trace of chitin. Paper chromatography of hydrolyzed cell walls showed that glucose and an unknown reducing compound make up the bulk of the carbohydrate fraction. Mannose and glucosamine were present in small amounts. The cell wall composition ofS. guttulata appears to differ considerably from that ofS. cerevisiae.

Classifying yeasts on punch cards

SummaryAttention is drawn to the advantages of punch cards for filing taxonomic information. A model system adapted to yeast taxonomy is presented.