The obligate psychrophilic yeasts Torulopsis psychrophila, T. austromarina, Leucosporidium frigidum, L. gelidum, and L. nivalis were obligate aerobes and were unable to grow anaerobically. In contrast, the obligate thermophilic yeasts T. bovina, T. pintolopesii, Candida slooffii, and Saccharomyces telluris were facultative anaerobes.

Aerobiosis↗

PubMed1977

Cell surface topography of Candida and Leucosporidium yeasts as revealed by scanning electron microscopy.

The cell surface topography of the following yeast strains was examined by scanning electron microscopy: Candida slooffii, C. lipolytica, Leucosporidium frigidum, and L. nivalis. Multipolar and lateral budding were observed in the Candida yeasts in contrast to bipolar budding in the Leucosporidium species. The cell surface topography and the morphology of the bud and birth scars in these yeasts differed markedly. Apart from the bud and birth scars, the cells of C. slooffii showed a relatively smooth topography. The bud scars were seen as a circular ridge of wall material surrounding a markedly convex scar plug. Birth scars were raised, rounded structures, which appeared to distend upon cell growth. In contrast, bud scars of C. lipolytica were platelike, lacked a distinct annulus of wall material, and were much less protuberent than those of C. slooffii. Birth scars were a more permanent feature of these cells. The topography of Leucosporidium yeasts was characterized by the presence of numerous protrusions on the cell surface. In some cases, the entire cell surface was covered by these protrusions. There appeared to be some correlations between the age of the cell and the extent of surface protrusions and degree of surface convolution...

Candida↗

PubMed1977

Fortification of hamburger with calcium, vitamin A, and ascorbic acid.

Patties were prepared from ground beef--some with and some without calcium, vitamin A, or ascorbic acid, either singly or in various combinations. After cooking, the patties were mixed with buns and mayonnaise, ground, and then fed to weanling rats. No single added nutrient or combination of added nutrients seemed to affect flavor, texture, or cooking losses of fat or water. Fortification with calcium and ascorbic acid increased liver storage of vitamin A and decreased liver:body weight ratios.

Animals↗

PubMed1976

Mitochondrial enzymes of tropical fish: a comparison with fish from cold-waters.

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Adaptation, Physiological↗

PubMed1976

Leucosporidium yeasts: obligate psychrophiles which alter membrane-lipid and cytochrome composition with temperature.

The temperature limits of growth of three psychorphilic yeasts, Leucosporidium frigidum, L. gelidum and L. nivalis, were examined. All species grew well as subzero temperatures (-I degrees C). The maximum temperature of growth was significantly higher with glucose as substrate (18 to 20 degrees C) than with ethanol (17 to 18 degrees C). There was a positive correlation between the growth temperature and the degree of fatty-acid unsaturation of the cell lipids; the lower the temperature, the greater the degree of fatty-acid unsaturation. At subzero temperatures (-I degrees C) with ethanol as substrate, 90% of the total fatty acid was unsaturated with linolenic (35 to 50%) and linoleic (25 to 30%) acids predominating. At temperatures close to the maximum for growth, linolenic acid accounted for less than 20% of the total fatty acid and oleic (20 to 40%) and linoleic (30 to 50%) acids were the major components. Difference spectra of intact cells showed marked changes in the rations and amounts of individual cytochromes as a function of growth temperature. In L.frigidum with glucose as substrate, the ratios of cytochromes a +a3:b:c at 8 and 19 degrees C were I:I-I:2-9 and I:2-3:16-7 respectively. Similar changes in cytochrome ratios were noted for L.gelidum, but changes were much less marked for L. nivalis. The temperature effects were interpreted as supporting the view that membrane structure and composition are fundamental to temperature adaptation in psychrophilic yeasts.

Basidiomycota↗

PubMed1976

Thermal adaptation in yeast: growth temperatures, membrane lipid, and cytochrome composition of psychrophilic, mesophilic, and thermophilic yeasts.

The temperature limits of growth of a number of yeast species were examined, and on this basis the organisms were classified into different thermal categories. The following species were examined: Leucosporidium frigidum and Leucosporidium nivalis, psychrophilic, temperature limits of growth, -2 to 20 degrees C; Canadian lipolytica mesophilic, temperature limits of growth, 5 to 35 degrees Candida parapsilosis and Saccharomyces telluris, thermotolerant, temperature limits of growth, 8 to 42 degrees C; Torulopsis bovina and Candida slooffi, thermophilic, temperature limits of growth, 25 to 45 degrees C and 28 to 45 degrees C, respectively. The membrane lipid and cytochrome composition of mitochrondrial fractions isolated from these yeasts were compared. There was a direct correlation between the growth temperature and the degree of membrane of lipid unsaturation; the lower the temperature, the greater the degree of lipid unsaturation. The membrane lipid composition of the thermophilic yeasts were distinguished by the high percentage (30 to 40%) of saturated fatty acid, as compared with the mesophilic and psychrophilic yeasts. The latter contained approximately 90% unsaturated fatty acid, 55% of which was linolenic acid, C alpha-18:3. Changes in phospholipid composition in relation to temperature were also noted. The respiratory-deficient thermophile, C. slooffi, was characterized by the absence of cardiolipin (sensitivity 0.1 mug of phosphorus) and cytochrome aa3. The absence of conventional mitochondrial structures in this thermophilic microorganism is tentatively suggested although low concentrations of cytochromes b, c, and c1 were detected by low-temperature spectroscopy. On the other hand, the respiratory-competent thermophile, T. bovina, was characterized by a high cardiolipin (25% of the total phospholipid) and cytochrome aa3 content (1 nmol/mg of mitochrondrial protein). Low-temperature spectra showed the presence of one b-type cytochrome in the thermophilic yeasts, two b-type cytochromes in the mesophilic yeasts, and three b-type cytochromes in the psychrophilic yeasts. It was concluded that a knowledge of the properties of the biological membrane is fundamental to an understanding of the ability of a microorganism to grow and reproduce in different temperature environments.

Adaptation, Physiological↗