1. For the purpose of producing yeast cells from petroleum oil, yeast which grow well on hydrocarbon-mineral salt medium were tested. Among several strains of hydrocarbon-utilizing yeast, Candida tropicalis YO-148 assimilated petroleum oil or hydrocarbons best. 2. Favorable culture conditions for growth of this yeast were ascertained. Cell yield was markedly increased by adjusting the culture medium to pH 7 during cultivation. Addition of a surface active agent, "Runox-M 210, " also increased the cell yield. Under the best conditions, 11g of dry yeast cells were obtained from 1liter of culture broth initially containing 10% (v/v) of light oil after 30hr cultivation. 3. Composition of hydrocarbon- and glucose-grown cells are also presented. One of the distinct features of hydrocarbon-grown cells was high crude fat (7%). Crude protein and RNA contents of hydrocarbon-grown cells were 44.7% and 5.1%, respectively. Essential amino acids, except sulfur-containing amino acids, in hydrocarbon-grown cells were higher than those in glucose-grown cells. The nutritional value of hydrocarbon-grown cells of this strain seems to be evenly matched to that of commercially available fodder-yeast cells produced from carbohydrates.
Ribonucleic acid synthesis in early stages of germination of Aspergillusoryzae conidia was studied using orthophosphate 32P or 14CO2 as precursor. RNA was fractionated by the methylated albumin-coated kieselguhr column chromatography or by the sucrose density gradient centrifugation analysis. RNA synthesis occurred at any time of germination so far observed and rRNA or its precursor was synthesized at the initial step of germination. sRNA synthesis occurred a little latter than the onset of germination and mRNA synthesis became apparent after 60min of incubation. Even in non-germinating medium (phosphate buffer), conidia could synthesize rRNA. It was suggested that the synthesis of rRNA or its precursor may be one of the starting reactions being driven at the very initial step of germination.
The production of glucoamylase (α-1, 4-glucan glucohydrolase) by Aspergillusniger, as a function of the composition of the growth medium was investigated. With D-mannose as the sole carbon source, the quantity and nature of the nitrogen compounds, as well as the amount of trace elements, were varied. The levels of glucoamylase, α-amylase (α-1, 4-glucan 4-glucanohydrolase), and glucosyltransferase produced by the A. niger were influenced by the kind of nitrogen, the concentration of both nitrogen and carbohydrate, the concentration of trace elements and the pH of the medium. Conditions were established for the production of glucoamylase with minimal quantities of α-amylase and glucosyltransferase.
The ruminal bacteria eluted from the rumen digesta solids, obtained from the rumen contents of sheep, 4hr after the administration of feed, were fractionated into three portions. The digesta solids were subjected to an elution treatment, first with simple salts solution and subsequently with the salts solution containing Tween 80. With this treatment, the first washing fraction (W1 fraction), second washing fraction (W2 fraction), and Tween fraction (T fraction) were obtained, respectively. Each fraction, including the gauze filtrate fraction, was studied for the distribution in those fractions of cell numbers for seven groups of cell types, and for nine representative strains isolated from the rumen contents. Chemical composition of the rumen digesta solids was investigated. The solids were enriched with crude fiber as compared with the supplied ration. There were only slight differences in the composition of the solids between both the rumen contents of animal, 4hr and 24hr after the administration of feed. G fraction was higher in number of cells compared to other fractions, and over one-half of the total rumen bacteria was distributed in this fraction. While, T fraction exceeded W fraction in cell number and contained ca. 23-28 per cent of the total rumen bacteria. The morphological features of the bacterial cells in each fraction were examined by means of the electron microscope. The group of small cocci was most abundantly distributed in each fraction and amounted to 58-65 per cent of total bacterial cells. Both groups of long and short rods followed the above group though in much smaller number. T fraction contained an appreciably higher number of long rods than other fractions. The distribution in each fraction of nine representative strains of the rumen bacteria was investigated by employing the fluorescent anti-sera method. It was observed that the distribution of the bacteria in the rumen contents was accomplished due to their physiological characters. The results obtained were assessed from the ecological point of view.
The biochemical features of bacterial population in the gauze filtrate fraction or other respective bacterial fractions gradually eluted from the digesta solids were examined for their activities towards cellulose, starch or succinate. The rumen contents of sheep fed hay and concentrates was squeezed through a layer of two sheets of gauze to obtain the digesta solids. The results obtained were as follows: 1) The distribution of Veillonella alcalescens in each fraction was examined on the basis of succinate decarboxylation. Values of QCO2 of G and W1 fractions exceeded those of W2 and T fractions and the pattern of distribution of QCO2 in each fraction was quite similar with pattern of the viable count of this species. 2) Gauze filtrate fraction was superior to the other fractions in the production of volatile fatty acid from cellulose or starch. Furthermore, T fraction showed considerable production of volatile fatty acids from starch, and in this respect exceeded W2 fraction although less in cell density. 3) G fraction was least active in cellulolytic activity compared to the other fractions. The amylolytic activity of G fraction was greater than the other fractions, followed by T fraction with a slight differences. Moreover, G fraction was most active in the proteolytic activity compared to the other fractions. 4) An attempt was made to adsorb the cells contained in G and T fractions on starch or cellulose. When the bacteria in G fraction were treated with starch, greater decrease in cell amount was observed than in T fraction. While, only a slight difference was indicated between both fractions at the treatment with cellulose. In the specific amylolytic activity of G fraction a significant decrease was well observed with the treatment with starch as compared with T fraction. The above results were discussed with relation to those of distribution of the rumen bacteria in each bacterial fraction as previously reported.
The infection of Bacillus subtilis Marburg strains with DNA of bacteriophage M2 was studied in comparison with the bacterial DNA transformation. The results of dose response experiment and dilution experiment suggested that the phage-DNA infection could be accomplished only by the simultaneous incorporation of at least four DNA fragments which determine the size of phage-DNA. These results were taken as evidence that there might be no intrinsic difference between the two phenomena.
Four RNA phages, β, Bl, and I isolated at our laboratory, and MS2 isolated in the United States were studied. 1) At 37°, plaque types of Bl and I were larger than those of β and MS2. At 45°, Bl and I gave pinhole-type plaques and β and MS2 medium size plaques which were as large as those at 37° 2) MS2 infected cells began to lyse in 45min after infection and β infected cells in 55-60min. The cells infected with Bl or I lysed to a negligible extent. 3) The four phages were serologically related and arranged in an order of β, MS2, Bl, I by the neutralization experiment. 4) Base composition of phage RNAs were studied. In MS2 RNA and β RNA, molar per cent of guanylic acid was larger than that of uridylic acid, and in Bl RNA and I RNA, molar per cent of uridylic acid was larger than that of guanylic acid. 5) Hybridization experiments were conducted between a double stranded RNA of β and a single stranded RNA of other phages. The result suggested that the β RNA was highly homologous with MS2 RNA, and to lesser extents with Bl RNA and I RNA. 6) Correlation between the serological character and the RNA structure is discussed.
By using a series of dry yeasts prepared to have various water contents, the resistivity to heat inactivation and cold medium treatment was studied. The heat resistance of the samples showed a marked dependence upon the water content, giving activation energies of 80kcal with relatively wet cells and 60kcal with relatively dried cells, respectively. The lowering of the biological activity shown after the rehydration with a cold medium was found to be prevented, at least partially, by preheating the sample at specified temperature before the rehydration procedure. This protective effect disappeared after several hour standing at room temperature, suggesting that the related physical state relaxed with a time constant of hours in order of magnitude. A domain map is presented to show diagrammatically the relationship between biological properties of the dry yeast and its related physical states in terms of the cell temperature and the cell water content.
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Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)