Growth of the yeast Torulopsis candida on n-alkanes

Yeast speciesTorulopsis candida was isolated from sea water and grew well on n-alkanes. The results are indicated below, and further studies will determine the economical value of utilizing this species in the industrial production of single-cell protein.This study was carried out at the Istituto di Microbiologia Agraria (DirectorProf. O. Verona), University of Pisa, Italy, during a scholarship offered by the foreign Office of the Italian Government.     

Effect of tridemorph on Torulopsis candida Berlese]

From the results of application of various inhibitors, or combinations of inhibitors to cell suspensions of the yeast Torulopsis candida and by determination of O2-consumption and growth rates it is concluded, that a main site of action of tridemorph is localized in the pathway of the respiratory chain. Tridemorph inhibits as well the respiration as the growth of T. candida depending on the concentration and the time of exposition. Tridemorph does not uncouple respiration but inhibits the uncoupled respiration to the same extent. Inhibition of respiration and growth by tridemorph is enhanced by suboptimal concentrations of antimycin A, oligomycin, rotenone, and 2,4-dinitrophenole. That leads to the conclusion that these inhibitors essentially enlarge the permeability for tridemorph which can be more rapidly transported to the site of action.     

Spheroplasts of Torulopsis candida yeasts and their oxidizing activity]

The paper describes the conditions in which the spheroplasts of the yeast Torulopsis candida IBFM-Y-127 with a high respiration rate can be isolated. The preliminary incubation of the cells with SH-reagents has to be carried out in a buffer without an osmotic stabilizer, and the incubation in a medium containing 0.6 M KCL, 0.1 M MgSO4, 0.1 MKH2PO4, pH 5.2. In these conditions the cells are incubated with the enzyme from Helix pomatia during 15 to 20 minutes, and the yield of the spheroplasts is 95 to 100 per cent. The spheroplasts oxidize various substrates (glucose, acetate, ethanol) at the same, or even higher, rate as the intact cells.     

Cyanide-resistant respiration in Torulopsis candida

The effect of cyanide and the inhibitors of cyanide-resistant oxidase--hydroxamic acids on endogenous respiration and oxidation of a number of substrates by Torulopsis candida resting cells taken at different stages of growth on glucose and hexadecane was studied and made it possible to arrive at the following conclusions. 1. The effect of cyanide on endogenous respiration of T. candida differs during its growth on glucose and hexadecane. On hexadecane, irrespective of the growth phage, cyanide inhibits endogenous respiration by 70--75%. On glucose, cyanide inhibits endogenous respiration not more than by 35% and only at the exponential growth phase whereas it stimulates endogenous respiration in the course of other growth stages. 2. The effect of cyanide on respiration of the resting cells of T. candida which oxidize glucose, hexadecane, primary alcohols and tetradecanoic acid hardly depends on the growth stage. It is determined mainly by the nature of a substrate to be oxidized. 3. Hydroxamic acid have no effect on the cell respiration in the absence of cyanide. However, in its presence, they entirely inhibit both endogenous respiration and oxidation of the aforementioned substrates. 4. Under almost all above experimental conditions, the sensitivity of cell respiration to cyanide changes only slightly at different stages of growth on either glucose or hexadecane. This feature markedly distinguishes T. candida among other cyanide-resistant yeasts.     

Isolation and morphological and biochemical characterization of mitochondria of yeast Torulopsis candida grown on glucose and hexadecane]

A method for isolating intact mitochondria from Torulopsis candida grown on glucose and hexadecane was developed. The isolated mitochondria were capable of oxidizing substrates of the di- and tricarboxylic acid cycle and of showing Chance respiration control. The morphological examination of the fractions showed that the major portion of mitochondria from yeast grown on glucose were in the condensed form whereas mitochondria from yeast grown on hexadecane were in the orthodoxal form.     

The three zinc-containing alcohol dehydrogenases from baker's yeast,Saccharomyces cerevisiae

This review is a summary of our current knowledge of the structure, function and mechanism of action of the three zinc-containing alcohol dehydrogenases, YADH-1, YADH-2 and YADH-3, in baker's yeast, Saccharomyces cerevisiae. The opening section deals with the substrate specificity of the enzymes, covering the steady-state kinetic data for its most known substrates. In the following sections, the kinetic mechanism for this enzyme is reported, along with the values of all rate constants in the mechanism. The complete primary structures of the three isoenzymes of YADH are given, and the model of the 3D structure of the active site is presented. All known artificial mutations in the primary structure of the YADH are covered in full and described in detail. Further, the chemical mechanism of action for YADH is presented along with the complement of steady-state and ligand-binding data supporting this mechanism. Finally, the bio-organic chemistry of the hydride-transfer reactions catalyzed by the enzyme is covered: this chemistry explains the narrow substrate specificity and the enantioselectivity of the yeast enzyme.     

Ascospore formation in yeasts related to Torulopsis candida

Ascospore formation was found in the type strains Torulopsis famata (Harrison) Lodder et Kreger van Rij, T. minor (Pollaci et Nannizi) Lodder and Candida flareri (Ciferri et Redaelli) Langeron et Guerra. The names of these species should be considered as a synonym of Debaryomyces hansenii (Zopf) Lodder et Kreger van Rij.     

Comparative study of the ultrastructural characteristics of Torulopsis candida yeasts grown on glucose and hexadecane]

Electron-microscopic examination of the ultrastructure of Torulopsis candida cells grown on glucose and hexadecane revealed a well-developed network of canals in the cell wall of yeasts grown on hexadecane. These canals appeared in the non-adapted cells at the initial hours of the cultivation and completed their formation at the end of the logarithmic phase. The investigation by the freeze-etching showed the exocytosis of "secretory granules" to take place at the periplasma of the cells, and the morphological relationship of the granules to the canals in the cell wall.