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Volume 63,
Issue 2,
1970
Volume 63, Issue 2, 1970
- Biochemistry
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A Study of the Esterases and Their Function in Candida lipolytica, Aspergillus niger and a Yeast-like Fungus
More LessSummary: Esterases, determined by polyacrylamide gel electrophoresis, were present when Candida lipolytica was grown in a liquid, shaken, glucose-mineral salts medium. Intracellular esterase activity increased during growth, but extracellular esterase activity was small and increased only marginally. Esterases were not detected in organisms grown on solid glucose-mineral salts medium, but were present when glycerol tributyrin replaced glucose.
At the onset of asexual sporulation in a yeast-like fungus, three new esterases occurred. Intracellular esterase activity increased, intracellular lipid utilization occurred, and the respiratory quotient decreased. No extracellular esterase activity was detected.
Esterases were only detected in Aspergillus niger at late stages of conidia-tion when intracellular lipid decreased. Esterase activity was not detected in the mitochondria or in the cell-free growth medium.
Esterases of all organisms tested hydrolysed glycerol tributyrin and were arbitrarily classified as lipases; intracellular lipid decreased with increase in esterase activity function. Esterase and profile changes may reflect a role of lipids in sporulation and physiological ageing.
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Purine Catabolism in Fusarium moniliforme
More LessSummary: Fusarium moniliforme utilized the purines hypoxanthine, xanthine and uric acid as sole nitrogen sources. Allantoin and urea supported relatively more growth. The methylated purines caffeine and theobromine were not utilized. Uric acid, allantoic acid, glyoxylic acid and ammonia were detected in culture filtrates. Xanthine dehydrogenase, uricase, allantoinase, allantoicase and urease were present in cell homogenates and cell-free extracts. Uric acid was degraded to allantoic acid via allantoin.
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Caproic Acid Metabolism and the Production of 2-Pentanone and Gluconic Acid by Aspergillus niger
More LessSummary: Vegetative hyphae of Aspergillus niger rapidly converted caproic acid to 2-pentanone whereas germinating spores carried out the transformation slowly and ungerminated spores not at all. Glucose stimulated ketone production by germinating spores, but suppressed it in hyphae; the degree of stimulation and suppression varied with glucose concentration. This explains earlier reports that spores but not vegetative hyphae convert fatty acids to methyl ketones, since hyphae were earlier tested with high sugar concentrations, conditions where ketone formation was inhibited. Glucose disappeared from cultures containing caproate even though ketone production was inhibited, and glucose disappearance was paralleled by gluconic acid accumulation in the medium. These findings suggest that free fatty acids may play an important role in the regulation of metabolic pathways in A. niger.
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- Development And Structure
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Electron Microscopic Observations on Growing and Dividing Protoplasts of Bacillus megaterium
More LessSummary: Protoplasts of Bacillus megaterium grew well and divided in 1 % casein hydrolysate (enzymic) medium containing 0·5 m-NaCl as the stabilizer. A fibrous layer of coat, possibly composed of murein, developed around the growing protoplast. A small protuberance then formed on the protoplast and grew until a symmetrical dumbbell-shaped body was formed. The coat did not develop around the ‘daughter’ protoplast.
Division was completely inhibited in the presence of penicillin, and a coat did not develop around the protoplast. Materials which might otherwise have formed the coat in the absence of penicillin were released into the medium.
After 12 h. of growth in the absence of penicillin, normal cell wall was formed around the cell, although reversion to bacillary form was not observed. The cells divided into 4 to 6 cells simultaneously by transverse septa, and intracellular membranous organelles (mesosomes) appeared within.
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Serological Properties of the Wall and Membrane Teichoic Acids from Lactobacillus helveticus NCIB 8025
More LessSummary: Both wall and membrane teichoic acids from Lactobacillus helveticus ncib8025 are glycerol phosphate polymers partially substituted with α-d-glucosyl residues. The membrane teichoic acid, isolated as a complex with lipid (lipoteichoic acid), was antigenic when injected into rabbits with Freund’s adjuvant. The α-d-glucosyl substituents are primarily responsible for the serological specificity of the membrane antigen, and account for the reaction of wall teichoic acid with antisera to the membrane teichoic acid. Glycerol teichoic acids either differing in or lacking sugar substitution may cross-react and the significance of these observations is discussed.
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- Genetics And Molecular Biology
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Two Mutations Affecting Utilization of C4-Dicarboxylic Acids by Escherichia coli
More LessSUMMARY: Studies with a mutant of Escherichia coli reported to be deficient in phospho- enolpyruvate carboxykinase activity (ab257suc −) indicate that it possesses two mutations. One affects growth on succinate (S −), and the other primarily affects growth on fumarate and malate and affects growth on succinate to a lesser extent (FM −). Neither of these mutations has a direct effect on carboxykinase activity. Presence of the S − mutation also prevents growth on acetate. It delays growth on other substrates such as lactate, glycerol and malate and it specifically inhibits the oxidation of succinate by mutant suspensions. The only biochemical lesion which could be detected was a deficiency in succinate dehydrogenase and it is thought that the S − locus may be situated in the structural gene for this enzyme. Transduction with phage P1 indicates linkages between S − and glt A and suc A of 97 and 90 %, respectively and the gene order S… suc A… gal was established. The FM − mutation was also found in the parental strain ab257. It affects the oxidation of succinate, fumarate and malate by mutant suspensions. The uptake of the dicarboxylic acids is also impaired but no other biochemical lesion could be detected. Genetic studies indicate that the FM − mutation is located near xyl.
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- Physiology And Growth
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Induction of Cellulase (Cx) in Verticillium albo-atrum
More LessSummary: Of a large number of sugars and polysaccharides, only cellulose substrates or cellobiose induced Cx (B-i,4-glucan glucano hydrolase; Enzyme Commission no. 3.2.1.4) in Verticillium albo-atrum. Many of the sugars tested inhibited the induction of Cx in the presence of carboxymethyl-cellulose (CM cellulose); this is explained on the basis of a balance between growth and enzyme production such that a low growth rate is usually coupled with high Cx levels and vice versa. One per cent glucose completely repressed Cx induction in 0·1 % cellobiose medium. Cellobiose caused slight inactivation of Cx by end-product inhibition. If the mycelium has no physical contact with insoluble cellulose in liquid cultures, virtually no growth occurs and Cx values are insignificant. These results are discussed in relation to the postulated C1 enzyme involved in the initial stages of cellulose degradation.
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The Utilization of Cellobiose by Verticillium albo-atrum
More LessSUMMARY: β-Glucotransferase was demonstrated in mycelial extracts and culture filtrates of Verticillium albo-atrum grown on 2 % cellobiose as the sole source of carbon. Analysis of the mycelium indicated relatively large amounts of cellobiose and gentiobiose, as well as small amounts of a series of three oligosaccharides (DP3,4, 5) and glucose; the same compounds were detected in the culture filtrate but at much lower concentrations (except for cellobiose) and glucose was barely detectable. Cellobiose phosphorylase was also present in mycelial extracts, and it is suggested that the production of glucose-1-phosphate from the phosphorylytic cleavage of cellobiose and its rapid utilization as a respiratory substrate explains why the fungus grows so much faster on cellobiose than on glucose. The level of these two enzyme systems is considered to be an important factor in controlling the rate of growth. The significance of the formation of oligosaccharides by the transferase system is discussed in relation to cellulose degradation.
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A Simple Chemically Defined Medium for the Production of Phase I Bordetella pertussis
More LessSUMMARY: A simple, chemically defined medium is described consisting of sodium glutamate, proline, cystine, salts, and growth factors, which is suitable for the large-scale production of phase I Bordetella pertussis. More than 30 × 109 organisms/ml. were produced in 48 to 72 h. growth in shake flasks and fer- mentors. The cultures were detoxified by the addition of 0·14 % formalin to yield vaccines which were non-toxic to mice and guinea pigs and had good mouse-protective antigen levels. The antigenic stability was satisfactory after storage of the final vaccines at elevated temperatures.
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Nutrition and Chemotaxis in the Myxomycete Physarum polycephalum: the Effect of Carbohydrates on the Plasmodium
More LessSummary: The ability of a range of carbohydrates to support the growth of plasmodia of the myxomyeete Physarum polycephalum was investigated and a method for the objective study of the chemotaxis of plasmodia was developed. Plasmodia showed positive chemotaxis to solutions of glucose, maltose, mannose and peptone, and to galactose after a delay. They did not respond to sucrose, fructose or ribose. The chemotactic effectiveness of sugars paralleled their ability to support growth.
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Comparison of Galactokinase Induction in Protoplasts and Intact Bacteria of Bacillus megaterium 216
More LessSUMMARY: Bacillus megaterium 216 was induced with d-galactose to form galactokinase (EC 2.7.1.6) in amounts comparable with those induced in Escherichia coli K12. When compared with the basal level, the increase was 20 times greater than in E. coli.
The greater the concentration of d-galactose, the greater the production of galactokinase in both protoplasts and whole bacteria. In each case the maximum amount of enzyme was induced by 5 mm d-galactose. d-Fucose, a gratuitous inducer, produced approximately half the specific activity of enzyme in protoplasts as d-galactose at any particular concentration. The yield of enzyme in the presence of an optimal concentration of d-galactose was increased when the medium was fortified with low concentrations of casein hydrolysate. The specific activities of galactokinase induced in protoplasts and in whole bacteria were respectively 148 % and 37 % greater in the presence of 0·01 % casein hydrolysate.
The maximum specific activity of galactokinase achieved after induction of protoplasts for 60 min. was 3·7 units/mg. protein compared with 12·5 units/ mg. protein in whole bacteria. However, over the first 15 min. after the addition of inducer the same specific activity of galactokinase was achieved in protoplasts as in whole bacteria.
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- Short Communication
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Decreased Uptake of Cadmium by a Resistant Strain of Staphylococcus aureus
More LessPenicillinase plasmids, and some related extrachromosomal elements in Staphylococcus aureus, can specify resistance to inorganic ions, including Hg2+ and Cd2+ (Richmond & John, 1964; Novick & Roth, 1968; Peyru, Wexler & Novick, 1969). There is some tentative evidence that resistance to Hg2+ ions is due to the impermeability of the cells to the ions and not to a higher concentration of free -SH groups in resistant cells (Vaczi, Fodor, Milch & Rethy, 1962), but the biochemical basis of resistance to cadmium ions is unknown. The experiments described here show that there is a markedly decreased rate of uptake of Cd2+ ions by resistant cells when compared with strains that lack the cad-r gene.
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- Taxonomy
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Comparison of Serological and Physiological Classification of the Genus Saccharomyces
More LessSUMMARY: The physiological and morphological properties of 28 species of the genus Saccharomyces were subjected to numerical analysis. Ten groups were distinguished, which agreed well with serological groupings, thus: (1) S. bailii, S. bisporus, S. mellis and S. rouxii, of serological group A; (2) S. carlsbergen- sis and S. cartilaginosus (A); (3) S. cerevisiae (AB); (4) S. oviformis, S. steineri and S. veronae (AC) and S. bay anus and S. pastorianus (C); (5) S. acidifaciens and S. elegans (AD); (6) S. fragilis and S. marxianus (B); (7) S. chevalieri (BC); (8) S. cerevisiae var. ellipsoideus, S. diastaticus, S. logos, S. uvarum, S. willianus and a further group of strains of S. carlsbergensis (all of group C); (9) S. fermentati, S. microellipsodes and S. rosei (D); (10) S. delbrueckii (D).
Serological classification offers results sufficiently close to those obtained by morphological and physiological tests to provide a rapid and reliable method of identification of Saccharomyces species.
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Division of Mycoplasmas into Subgroups
More LessSUMMARY: The deoxyribonucleic acid (DNA) base compositions of 12 recently isolated or new species of mycoplasmas fell within the range known for the Mycoplasma group. By DNA-DNA hybridization a new sterol-nonrequiring strain, s-743, was unrelated to Mycoplasma laidlawii or M. granularum, the latter two strains showing moderate cross-reactivity; swine strain B3 appeared to be related to M. mycoides var. capri. From these results and information in the literature, the mycoplasmas have been divided into six provisional subgroups on the basis of physiological characters, DNA base composition and nucleic acid hybridization. Some speculations are made on the significance of heterogeneity among mycoplasmas.
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