- Volume 116, Issue 2, 1980
Volume 116, Issue 2, 1980
- Physiology And Growth
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The Effect of Sporulation Medium on Spores of Clostridium bifermentans
More LessSpores of Clostridium bifermentans produced on a Trypticase medium (TRY) and on reinforced clostridial medium (RCM) were compared. RCM-spores contained less dipicolinic acid, outgrew more slowly, were less resistant to hydrogen peroxide and to heat and lost more dipicolinic acid on heating. After treatment with urea/mercaptoethanol both TRY - and RCM-spores germinated with lysozyme, although heating RCM- but not TRY-spores before urea/mercaptoethanol treatment decreased their subsequent germination rate. In thin-section electron micrographs, TRY-spores showed thicker cortices and smaller protoplasts with less visible ribosomes than RCM-spores. The sporulation medium evidently has a marked effect on spore properties. Resistance to heat and to hydrogen peroxide appears to be related to spore structure.
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Oxidation of Dimethyl Ether, Methyl Formate and Bromomethane by Methylococcus capsulatus (Bath)
More LessSuspensions of Methylococcus capsulatus strain Bath oxidized dimethyl ether, methyl formate and bromomethane. The rate of disappearance of dimethyl ether was enhanced up to 11-fold in the presence of co-substrates such as formaldehyde. Dimethyl ether was oxidized by the purified methane mono-oxygenase from M. capsulatus (Bath) to give various amounts of methanol and formaldehyde. As M. capsulatus (Bath) cannot grow on dimethyl ether it was concluded that this ether is a non-growth substrate which can be fortuitously oxidized. Possible reasons for the lack of growth on dimethyl ether are discussed. Methyl formate and bromomethane were oxidized by the purified methane mono-oxygenase to yield equal stoicheiometric amounts of formaldehyde and formic acid, and formaldehyde alone, respectively. Methylococcus capsulatus (Bath) grew on methyl formate but not on bromomethane and it was concluded that the latter is a non-growth substrate which can be fortuitously oxidized. Preliminary evidence is presented for carbon assimilation during the oxidation of bromomethane.
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Glucose Phosphoenolpyruvate Phosphotransferase Activity and Glucose Uptake Rate of Klebsiella aerogenes Growing in Chemostat Culture
More LessGlucose-limited cultures of Klebsiella aerogenes NCTC 418 (and the supposedly identical strain NCIB 418) possessed a glucose phosphoenolpyruvate (PEP) phosphotransferase activity that varied markedly and progressively with growth rate, from more than 250 nmol min−1 (mg dry wt cells)−1 at D = 0·1 h−1 to less than 100 nmol min−1 (mg dry wt cells)−1 at D = 0·8 h−1. When relieved of the glucose limitation, substrate was used at a rate that bore no precise relationship to the cells’ phosphotransferase activity. Similarly, glucose-sufficient (phosphate- or potassium-limited) cultures metabolized glucose at high rates, whereas the cells possessed only moderate glucose PEP phosphotransferase activities. These results are compared with those reported for glucose-limited cultures of Escherichia coli and for variously limited cultures of K. aerogenes. Glucose-sufficient cultures, as well as glucose-limited cultures that had been temporarily relieved of glucose limitation, excreted partially oxidized products of glucose catabolism in considerable amounts. The relevance of this ‘overflow’ metabolism to studies of glucose transport using [U-14C]glucose is emphasized.
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Cross-pathway Regulation of Ornithine Carbamoyltransferase Synthesis in Aspergillus nidulans
More LessRegulation of the cross-pathway type was found in Aspergillus nidulans. Ornithine carbamoyltransferase, a biosynthetic enzyme of the arginine pathway, is derepressed as a result of deprivation not only of arginine but also of histidine, proline and tryptophan. Cross-pathway regulation operates in the mutant suD19 in which the ornithine carbamoyl-transferase level is insensitive to arginine. The spectrum of the amino acids involved in this type of regulation seems to be different from those described for other fungi.
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Catabolism of l-Arginine by Pseudomonas aeruginosa
More LessPseudomonas aeruginosa is known to break down arginine by the arginine deiminase pathway. An additional pathway has now been found whereby arginine is converted to putres-cine with agmatine and N-carbamoylputrescine as intermediates. The following enzyme activities belonging to this pathway were detected in crude extracts: arginine decarboxylase (EC 4.1.1.19), which catalyses the release of CO2 from arginine to give agmatine; agmatine deiminase (EC 3.5.3.12), which degrades agmatine to N-carbamoylputrescine; and N-carbamoylputrescine amidinohydrolase (EC 3.5.3.-), which then removes the ureido group of carbamoylputrescine. In crude extracts, arginine decarboxylase activity was stimulated by pyridoxal phosphate, Mg2+ and by the products of the catabolic pathway, putrescine and spermidine.
Growth of P. aeruginosa on arginine as the sole carbon and nitrogen source markedly increased the activity of arginine decarboxylase. Agmatine and N-carbamoylputrescine induced the synthesis of agmatine deiminase and N-carbamoylputrescine hydrolase. Addition of succinate or citrate to medium containing arginine or agmatine led to repression of the agmatine deiminase and N-carbamoylputrescine hydrolase was further increased when P. aeruginosa was grown in media with agmatine plus glutamine or agmatine plus succinate and ammonia. This suggests that the expression of the agmatine pathway may be regulated by carbon catabolite repression as well as nitrogen catabolite repression.
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N-Carbamoyl-βd(+)-glucopyranosylamine Metabolism by Rumen Microbes
More LessDegradation of N-carbamoyl-β-d(+)-glucopyranosylamine (NCG) by rumen micro-organisms in vitro required a viable population as it did not occur if the microbial preparation had been sterilized. Production of CO2 from glucose, or the glucose portion of NCG, was not affected by acetohydroxamic acid (AHA), but urea hydrolysis was inhibited by 79%. With N-[14C]carbamoyl-β-d]carbamoyl-β-d(+)-glucopyranosylamine, production of 14CO2 decreased and [14C]urea accumulated when AHA was included in the medium. Cell-free rumen fluid did not degrade NCG. These observations support the hypothesis that the first nitrogenous component formed from the degradation of NCG is urea.
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Metabolism of Naphthalene by the Cyanobacterium Oscillatoria sp., Strain JCM
More LessOscillatoria sp., strain JCM grown photoautotrophically in the presence of naphthalene oxidized the aromatic hydrocarbon to cis-1,2-dihydroxy-1,2-dihydronaphthalene, 4-hydroxy-1-tetralone and 1-naphthol. The major metabolite was 1-naphthol. Each product was isolated and shown to have ultraviolet and mass spectra identical to those of authentic compounds. In addition, each metabolite had properties identical to those of authentic compounds when analysed by thin-layer, high-pressure liquid and gas-liquid chromatography. Experiments with [14C]naphthalene showed that, over a 24 h period, the organism oxidized 4·8 % of the added naphthalene. The ratio of organic-soluble to water-soluble metabolites was 41:59. Incubation of whole organisms with naphthalene and 18O2 led to the isolation of 1-naphthol that contained 18O. The organism oxidized 1-[14C]naphthol to 4-hydroxy-1-tetralone. The mechanism of naphthalene oxidation by this cyanobacterium is discussed.
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Oxidation of Naphthalene by Cyanobacteria and Microalgae
More LessEighteen different algal cultures were examined for their ability to metabolize naphthalene. The strains tested included nine cyanobacteria (blue-green algae), five green algae, one red alga and one brown alga; two diatoms were also examined. All these organisms oxidized naphthalene under photoautotrophic conditions. Experiments with [14C]naphthalene showed that each organism oxidized naphthalene to at least six metabolites. One of the metabolites was identified as 1-naphthol. Under the experimental conditions used in this study the extent of naphthalene metabolism to organic-soluble derivatives ranged from 0·1 to 2·4%.
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- Short Communication
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A Procedure for Isolating High Quality DNA from Spores of Bacillus subtilis 168
More LessA method of isolating DNA from spores of Bacillus subtilis is described. The DNA has approximately the same efficiency in genetic transformation as DNA isolated from vegetative cells and gives a restriction pattern similar to that from vegetative DNA.
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The Cell Surface in Amoeboid Locomotion: Behaviour of Naegleria gruberi on an Adhesive Lectin Substrate
More LessThe behaviour of Naegleria gruberi amoebae on coverslips coated with concanavalin A was followed by reflection interference microscopy. Locomotion continued briefly on the protein and much material was shed before the cells halted. The effect was overcome by perfusion with hapten sugars. These carbohydrates dissociated those trails formed in water from the substrate save for areas of focal contact, whereas trails generated in 10 mm-KCl were unaffected by hapten. These results argue for direct cell-substrate contact over a limited portion of the cell surface during this type of locomotion.
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Specificity of Exochelins for Iron Transport in Three Species of Mycobacteria
More LessIron chelated to the water-soluble extracellular iron-binding compound (exochelin) from Mycobacterium smegmatis was taken up by that organism by an energy-coupled transport system which was not found in M. bovis BCG or M. intracellulare. The uptake of iron from the chloroform-soluble exochelins produced by the latter two species was by an inhibitor-insensitive system which was also found in M. smegmatis.
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Genetical Analysis of a Sterile Mutant by Protoplast Fusion in the Fission Yeast Schizosaccharomyces pombe
More LessThe genetical analysis, by protoplast fusion, of the sterile strain ED22 of Schizosaccharomyces pombe is described. Two major mutations are harboured by this strain. One, cdc 25·22, is conditionally defective in mitosis. The other mutation, ste 1·1, causes sterility in strains of h −, h + or mat 2·102 mating-type. Sterility is due to the failure of cell agglutination. We present evidence that ste 1·1 is defective in the production of a non-diffusible and non-mating-type specific factor. ste 1 and cdc 25 both map on chromosome I and are loosely linked.
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Autoradiography of Haustoria of Erysiphe pisi
More LessLeaves of Pisum sativum infected with Erysiphe pisi were exposed to 14CO2 for 2 h, and then haustorial complexes were isolated. The distribution of 14C in the isolated fraction was studied by light microscopic autoradiography. Solvent extraction prior to autoradiography indicated that most of the 14C resided in compounds insoluble in ethanol, chloroform and methanol. The haustorial complexes contained 82 to 84 % of the 14C in the fraction. Considerable variation, not correlated with haustorium age, was found in the labelling of individual haustorial complexes.
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Intracellular Concentrations of Citric and Isocitric Acids in Cultures of the Citric Acid-excreting Yeast Saccharomycopsis lipolytica Grown on Alkanes
More LessThe intracellular concentrations of citric and isocitric acids were very low for most of the growth cycle of Saccharomycopsis lipolytica on alkanes. They increased linearly during the phase of acid excretion and the intracellular concentration was similar to the extracellular concentration (for citric acid) or a little below (for isocitric acid). The high ratios of isocitric to citric acid observed in the external medium (0·73) and in the internal pool (0·42) may be explained by compartmentalization of the metabolism of these acids which probably involves a selective transport of isocitric acid from the mitochondrion to the cytoplasm. The results suggest that acid excretion from the cytoplasm to the external medium takes place by diffusion.
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Sterol Requirement for the Growth of Treponema hyodysenteriae
More LessThe addition of cholesterol to a liquid medium containing bovine serum albumin (BSA) fraction V or acetone-delipidized BSA fraction V instead of serum stimulated the growth of Treponema hyodysenteriae, a serum-requiring spirochaete associated with swine dysentery. As little as 1·25 μg cholesterol ml−1 increased viable counts about 1000-fold. Sitosterol and cholestanol, but not pregnenalone, cholestenone or stigmasterol, produced a growth response comparable to that of cholesterol. The results suggest that T. hyodysenteriae requires a sterol for growth.
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Crude Lysates of Staphylococcus aureus Can Transform Bacillus subtilis
More LessPlasmids can be transferred from Staphylococcus aureus to Bacillus subtilis by crude lysates prepared with penicillin or lysostaphin. These lysates mediate drug-resistance plasmid transformation in competent B. subtilis at an efficiency paralleling that of purified DNA.
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Physicochemical Characteristics of Listeria Specific Antigen 2
Listeria specific antigen 2 (Ag2) was purified to within 97 % of homogeneity, with a high yield, using both gel filtration and polyacrylamide gel electrophoresis. Ag2 is a glycoprotein. Its isoelectric point is about 4·2. As determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, its molecular weight is 16710 ± 450. Ag2 may aggregate easily since it was previously found in gel filtration in a peak corresponding to a molecular weight of 160000. No enzyme activity has been found in Ag2.
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Properties of a Transmissible Plasmid Conferring Citrate-utilizing Ability in Escherichia coli of Human Origin
More LessTransfer of citrate utilization (Cit+) was achieved with a plasmid (pCIT354) which is Fi+, has F-like pili and fails to inhibit phage propagation. Transduction of Cit+ was achieved with P1 phage. Results of incompatibility tests with R plasmids indicated that pCIT354 is a self-repressed F-like plasmid.
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