Blood constituents of yeast fed chicks

Two experiments on broiler chicks raised to 4 weeks of age were carried out to study the effects of replacing soybean protein in a semisynthetic diet with yeast protein from molasses (CEPAH). Criteria measured were body weight, feed efficiency, plasma urea nitrogen, serum uric acid, serum total protein, albumin, globulin and albumin-globulin ratios. Analysis of the data showed that yeast protein produced from molasses depressed growth and feed efficiency at levels 10, 15, and 20% of the diet. The effects of yeast protein on blood nitrogenous constituents were variable and not significant, but in general, the inclusion of yeast protein caused an increase in serum albumin and a decrease in serum globulin resulting in a higher albumin-globulin ratio. The changes observed in blood nitrogenous constituents in this study do not explain all the detrimental effects of yeast protein on growth and feed efficiency of chicks receiving high levels of such protein.

Reduction of hepatic lipid deposition in laying hens by dietary selenium-yeast interaction

Experiments were conducted to study the effect of chromiun and selenium on liver lipid deposition and incidence of liver hemorrhage in caged layers. Commercial strains of layers were fed ad libitum equicaloric and isonitrogenous diets. Corn-torula dried yeast diets containing added selenium (.1 microgram/g) with or without supplementary chromium (10 microgram/g) significantly reduced total liver lipid and liver hemorrhage. The effects of protein source (soybean meal vs. yeast) and selenium were separated in a factorial experiment which showed that the hepatic lipid response to selenium results from an interaction of selenium with an unidentified factor in torula yeast. The addition of selenium to diets with each protein source significantly elevated glutathione peroxidase (GSHPx) activity. Inclusion of 5% brewers yeast in the corn-soy diet or vitamin E (50 IU/kg) to the corn-torula dried yeast reduced liver lipid similar to that seen in birds fed the torula-yeast diet containing .1 microgram Se/g. Comparison of oral glucose tolerance of birds fed corn-soy and corn-soy brewers yeast diets showed no significant difference. None of the dietary treatments significantly altered body weight, egg production, egg weight, or feed consumption. The results indicate that the metabolic role of selenium in relation to its role in hepatic lipid metabolism is mediated through an interaction with a dietary factor(s) present in yeast.

Plasma lipid and lipoprotein responses of rats to starch and sucrose diets with and without brewer's yeast

The effect of starch and sucrose diets, with and without brewer's yeast, on plasma total cholesterol and triglyceride concentration and on the lipoprotein distribution in plasma was studied in male rats. The rats were fed a cereal based stock diet, a starch or a sucrose diet, plus or minus brewer's yeast, for 4 weeks. The plasma cholesterol concentration increased to similar levels in rats fed the starch or the sucrose diets but remained unchanged in rats fed the stock diet. The plasma triglyceride level increased in rats fed stock diet, but was unchanged in those fed starch or sucrose diets. Brewer's yeast did not modify the cholesterol value in any of the three groups but reduced the triglyceride level in rats fed the stock and the starch diets. In rats fed the starch diet there was a reduction in the relative amount of prebeta lipoproteins, but no significant alterations in the beta, prealpha and alpha fractions, as compared with rats fed stock diet. Rats fed the sucrose diet had lower prebeta, beta and alpha lipoprotein percentages and a much higher prealpha percentage than rats fed the stock diet. Brewer's yeast had no consistent effects on the lipoprotein distribution. The results support the contention that there might be a dissociation between dietary effects on the plasma lipid level and on the lipoprotein distribution.

Cloning of Drosophila cells: effect of vitamins and yeast extract components

Yeast extract, a component of Drosophila cell culture media, is shown to contain substances of high, intermediate, and low molecular weight, that are, respectively, essential, inhibitory, and stimulatory for colony formation in semisolid agar medium. Furthermore, it is shown that high concentrations of pyridoxal greatly increase the cloning efficiency of Drosophilia cells. A cloning method with line Kc is described which routinely gives cloning efficiencies in excess of 20%.

[Effect of cell reserve carbohydrates on an increase in the keeping qualities of baker's yeast]

Synthesis of reserve carbohydrates (trehalose and metabolically active glycogen) can be intensified in the cells of Saccharomyces cerevisiae by adding glycerol and magnesium or phosphorus salts to the cultural broth. An increase in the content of reserve carbohydrates in the cells increases their preservation after separation from the substrate.

[Effect of different nitrogen sources on the biosynthesis of lipase by Oospora lactis]

The effect of inorganic and organic nitrogen compounds on the synthesis of biomass and extracellular lipase by Oospora lactis was studied. Among the inorganic nitrogen sources ammonium sulphate and ammonium secondary phosphate and among the organic nitrogen sources yeast autolysate proved to be most beneficial for the lipase synthesis. Lipase activity and biomass accumulation in the medium containing yeast autolysate were greater than in the media containing the above ammonium salts. Lipase synthesis reached maximum in the nutrient medium containing yeast autolysate (0.7%) and ammonium sulphate (0.3%).

Selective effect of fractions of a yeast extract (PCO) on normal and malignant cells

The selective action of two fractions of PCO (a yeast extract) on normal and malignant cells was demonstrated. In vivo, the mitotic activity of malignant cells was inhibited by the methanol-insoluble fraction of PCO, whereas the methanol-soluble fraction caused no inhibition. The in vitro studies, however, showed inhibition of mitoses with both fractions. The malignant cells employed in vitro and in vivo were the Krebs-2 and Ehrlich carcinomas. The nonneoplastic cells tested in vitro were established cultures of epithelial-like cells from murine bone marrow and thymus, and corneal epithelium and peripheral blood in vivo.

Studies on Hymenolepis microstoma in vitro. II. Effect of yeast extract on development and maturation

Four day old in vivo Hymenolepis microstoma were cultured in vitro for 6 days in media containing 2, 1, 0.5 and 0.1% yeast extract. Worms from all groups including control group increased in length and produced nearly equivalent numbers of proglottids. However, worms grown in yeast extract added media produced significantly more mature proglottids and were heavier than those in the control medium. The possibility of pyridoxin involvement has been contemplated. Effects of osmotic pressure and pH on the development of worms are discussed.

Studies on unidentified growth factors. 1. Factor G, a growth factor for rats

1. Weanling rats were given diets containing all the nutrients known to be required, with L-amino acids in place of protein. Dietary supplements were added isonitrogenously.

2. Torula yeast (50 g/kg diet) and dried brewers' yeast (50 g/kg) significantly improved the rats' growth rate. Part of this activity was attributed to the minerals present in the yeasts, zinc, iodine, iron, copper and manganese all being implicated.

3. Marmite (20 g/kg) and a basic fraction (6.6 g/kg) obtained from it by cation-exchange chromatography significantly improved growth. The ash component of the basic fraction was inactive.

4. Growth was increased by an extra supplement of vitamins and by treating the rats with neomycin sulphate and tetracycline. The growth stimulus due to Marmite was additive with that due to the antibiotics, but not with that due to the vitamin supplement.

5. The growth rate with torula yeast (50 g/kg) was maintained at about 30% greater than on the basal diet during a test lasting 80 d. At the end of that period six control and five supplemented male rats sired normal litters. Post-mortem examination, including histology, of others showed no abnormalities due to factor G deficiency.

6. Fresh ox liver (100 g/kg diet) significantly improved the growth rate, but this improvement could be attributed to the effects of the water and minerals contained in the liver.

7. These results confirm the discovery by Schwarz, Smith & Oda (1966) that yeasts contain an organic growth-promoting factor (factor G) for rats receiving amino acid diets. Factor G is not likely to be one of the vitamin B group.

Cultivation of Mycoplasmas on glass

Eight Mycoplasma species of human origin were successfully cultivated on glass. Complement-fixing (CF) antigens prepared from glass-adherent mycoplasmas were potent, specific, and free from anticomplementary activity. PPLO broth medium supplemented with 1 to 5% PPLO serum fraction (bovine), 2.5% fresh yeast extract, and 1% glucose (glycolytic species) or 1% arginine (arginine-utilizing species) supported moderate to luxuriant growth of mycoplasmas on glass. The potency of CF antigens prepared from glass-adherent mycoplasmas varied with the species of Mycoplasma tested and the duration of incubation. When the potency of CF antigens prepared from glass-adherent mycoplasmas was compared with that material sedimented from the broth phase of the same culture, three patterns of growth were observed: M. hominis and M. orale type 2 grew preferentially in the broth phase; M. salivarium, M. orale types 1 and 3, M. pneumoniae, and M. lipophilum preferentially adhered to the glass; and M. fermentans was biphasic. The growth of mycoplasmas on glass provides a simple means of concentrating and purifying such organisms for immunological and biochemical studies.

The influence of nitrogenous compounds on growth of Pythium species

The utilization of N compounds by P. ultimum Trow (strain I and II), P. rostratum Butler, and P. irregulare Buisman was examined in a chemically denned medium under controlled conditions in surface culture. All species were able to metabolize nitrate, ammonium, and organic nitrogen, and the amount of growth varied with the nitrogen source. In general, yeast extract, peptone, glycine, serine, histidine, cysteine, asparagine, aspartic acid, and glutamic acid supported favorable growth, whereas γ-aminobutyric acid, threonine, and alanine supported poor growth of these fungi. The addition of succinic acid at 0.02 M concentration to ammonium compounds further increased growth of four isolates.Preferential utilization of amino acids from a given mixture was recorded using paper chromatographic techniques. All four isolates gave more vegetative growth on mixtures of amino acids than when they were supplied singly.