- Volume 117, Issue 1, 1980
Volume 117, Issue 1, 1980
- Physiology And Growth
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Fatty-acyl Composition of the Lipids of Saccharomyces cerevisiae Grown Aerobically or Anaerobically in Media Containing Different Fatty Acids
More LessSaccharomyces cerevisiae grew at the same rate aerobically in a glucose/salts medium as anaerobically in a defined medium supplemented with ergosterol and either oleic, linoleic or α-linolenic acid. However, exponential growth extended for a longer time in aerobic cultures. Irrespective of the nature of the fatty acid provided, phosphatidylcholine from anaerobically grown organisms harvested from early mid-exponential phase cultures contained a higher proportion of residues chemically identical with that provided in the medium compared with the phospholipid from organisms harvested at later stages of batch growth. The fatty-acyl composition of phosphatidylethanolamine and of a fraction containing phosphatidylinositol and phosphatidylserine showed similar changes to those found in phosphatidylcholine. Similar trends were also detected in the fatty-acyl composition of triacylglycerols from organisms grown anaerobically in the presence of different fatty acids and harvested at different stages of growth. However, at all stages of growth there was a higher percentage incorporation of the exogenously provided acid into triacylglycerols. The fatty-acyl composition of individual classes of phospholipid and of triacylglycerols from aerobically grown organisms remained remarkably constant throughout growth in batch culture. There were, however, characteristic differences in the fatty-acyl composition of different classes of lipid.
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Extracellular Cellulase Production by Sporocytophaga myxococcoides NCIB 8639
More LessSporocytophaga myxococcoides NCIB 8639 utilized a number of cellulosic substrates and produced extracellular carboxymethylcellulase and activity towards Avicel (a milled micro-crystalline cellulose powder). Both types of enzyme were synthesized in media containing glucose but the activity was influenced by the nature and concentration of the carbon source. The ratio of carboxymethylcellulase activities measured by reducing sugar production and by viscosity decrease was also influenced by the nature of the cellulosic substrate supplied to cultures. The greatest extracellular enzyme production occurred in cultures grown on microcrystalline cellulose powders such as Avicel and Whatman CC31 at concentrations up to 4% (w/v). The greatest degradation rate observed was in cultures supplied with Avicel where 60 % of the substrate was degraded in 4 d.
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- Short Communications
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Transposition of Tn951 (Tnlac) and Cointegrate Formation are Thermosensitive Processes
More LessThe frequency of transposition of Tnlac to pGC200, an IncFII R plasmid, increased during the storage of the host strain. This result is explained by the fact that the transpositional event is temperature-dependent: it occurred readily when the host strain was grown at 30°C but it was nearly undetectable when the host strain was grown and kept at 37°C. Fusions between two different plasmids carrying Tnlac with pGC200 were also thermosensitive, suggesting a relation between cointegrate formation and transposition. Lactose did not influence the frequency of transposition of Tnlac.
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Disappearance of Nystatin Resistance in Candida Mediated by Ergosterol
Jaime Mas and Enrique PiATwo nystatin-resistant mutants of Candida were isolated in vivo and identified as C. albicans and C. krusei. Analysis of the sterol composition of these cells indicated a total absence of ergosterol and an increased level of a possible precursor. Successive cultures of the resistant strains in a medium supplemented with 10 μg ergosterol ml−1 induced in 5 d a sensitivity to nystatin identical to that of the wild-type strain. These ergosterol-supplemented strains had an ergosterol content similar to that of the wild-type strain cultured in the absence of ergosterol. Resistance to nystatin was recovered after 5 d subculture in medium without ergosterol.
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Inhibition of Sterol Biosynthesis in Candida albicans by Imidazole-containing Antifungals
More LessA simple procedure for studying sterol biosynthesis in cell-free homogenates of Candida albicans is described. The activities of some imidazole-containing antifungals (tioconazole, clotrimazole, econazole, ketoconazole and miconazole) as inhibitors of sterol C-14 demethylation have been determined using this technique.
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A Mutant Defective in Electron Transfer to Nitrate in Escherichia coli k12
More LessA mutant of Escherichia coli K12 is described which is unable to reduce nitrate with a variety of physiological electron donors but which retains nitrate reductase activity with the artificial electron donor benzyl viologen. It is suggested that the affected gene, chlI, located close to chlC, encodes the cytochrome b nr apoprotein.
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Gradient Elution from a DEAE-cellulose Column of Capsulate and Non-Capsulate Strains of Klebsiella aerogenes
More LessKlebsiella aerogenes strains A3 and A3(0) which had been grown at 37°C on nutrient agar medium were applied to a DE-52 cellulose/CC-31 cellulose column and eluted with a linear NaCl gradient in 0·05 m-phosphate buffer, pH 6·0. Characteristic elution profiles were observed: the encapsulated, slime-forming strain A3 gave an elution peak with 200 mm-NaCl and the non-capsulate, non-slimy strain A3(0) with 90 mm-NaCl. These observations may be interpreted in terms of ionic interactions between DEAE-cellulose and components of the cell surface.
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A Screening Method for the Estimation of Filter Paper Activity
More LessA simple method which enables rapid screening of cellulase activity was devised. The results of this test correlated with those obtained using published methods for determining filter paper activity.
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Intracellular Distribution of Carbon Dioxide-fixing Enzymes in Trypanosoma cruzi and Crithidia fasciculata
More LessThe intracellular distribution of phosphoenlpyruvate carboxykinase (EC 4.1.1.49) and NADP-linked malic enzyme (EC 1.1.1.40) activity in epimastigotes of Trypanosoma cruzi (Tulahuén strain) and in Crithidia fasciculata has been studied by two procedures: (i) subcellular fractionation by differential centrifugation of homogenates obtained by breaking the cells in a mortar; (ii) selective disruption of cellular membranes by digitonin treatment. Phosphoenlpyruvate carboxykinase is particulate in both organisms, as is one of the two forms of malic enzyme present in T. cruzi (malic enzyme I), whereas the other malic enzyme of T. cruzi (malic enzyme II) and the single malic enzyme of C. fasciculata are in the cytosol.
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Isolation of a Non-adhesive Mutant of Vibrio cholerae and Chromosomal Localization of the Gene Controlling Mannose-sensitive Adherence
More LessA mutant (CD11) of Vibrio cholerae was isolated after exposure of a wild-type pathogenic strain (KB207) to N-methyl-N′-nitro-N-nitrosoguanidine. Although the mutant was motile and chemotactic, it adhered poorly to rabbit intestinal mucosa. Pretreatment of vibrios with 10 mg d-mannose ml−1 and of intestinal mucosa with 100 mmol sodium metaperiodate inhibited adherence of KB207 but not of CD11. The gene (ams) controlling mannose-sensitive adherence was mapped on the bacterial chromosome closely linked to the pur locus.
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Localization of Cholinesterase in Pseudomonas aeruginosa Strain K
More LessThe inducible cholinesterase of Pseudomonas aeruginosa strain K (ATCC 25102) degraded propionylcholine, acetylthiocholine, acetylcholine and acetyl-β-methylcholine at a high rate and butyrylcholine and succinylcholine at very low rates. The localization of the enzyme in the periplasmic space was indicated by a similar rate of acetylcholine degradation by intact cells or their extracts, by release of cholinesterase together with alkaline phosphatase into the culture medium during cell growth in a low phosphate-containing medium, by liberation of cholinesterase and alkaline phosphatase during lysozyme-induced conversion of cells to spheroplasts and by freezing and thawing. Treatment of cells with diazo-7-amino-1,3-naphthalenedisulphonic acid, which inactivates surface-located enzymes, abolished most of the cholinesterase and 5′-nucleotidase activities.
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- Taxonomy
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Properties of a New Group of Alkalophilic Bacteria
More LessFive strains of a new alkalophilic bacterium have been isolated from potato-processing effluent. These strains are Gram-positive, non-sporing, motile rods which form an orange, cell-bound pigment and are capable of growth in aerobic or anaerobic conditions at a pH up to 11·5 and between 7 and 43°C. For one representative strain the highest growth rate occurred in the pH range 8 to 10·5 and the minimum doubling time observed was 27 min at approximately 38°C. With glucose as substrate, lactate, acetate and formate were major end-products, the proportions depending on cultural conditions.
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Isoenzymes in Two Species of Acholeplasma
More LessThe reference strains Type A and Type B and two equine strains of Acholeplasma laidlawii were examined for a wide range of isoenzymes using thin-layer starch-gel electrophoresis; in addition two isoenzymes were examined in two strains of A. equifetale. The type strains A and B of A. laidlawii were differentiated by their lactate dehydrogenase, phosphogluco-mutase and aspartate aminotransferase patterns and the two equine strains by their hexo-kinase, lactate dehydrogenase and phosphoglycerate kinase patterns. The two pairs of strains differed from one another with respect to hexokinase, phosphoglucomutase, adenylate kinase and glucose-6-phosphate dehydrogenase. The two strains of A. equifetale could be distinguished by their isoenzymes of hexokinase. The two species were differentiated by their hexokinase and phosphoglucomutase patterns.
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Chemical Studies on Some Bacteria which Utilize Gaseous Unsaturated Hydrocarbons
More LessLipid and DNA studies on eight Gram-positive bacteria capable of utilizing gaseous unsaturated hydrocarbons as sole carbon sources indicated that the one strain which utilized acetylene as sole carbon source was a member of the genus Rhodococcus. The remaining seven strains which utilized ethylene and/or propylene as sole carbon sources all appeared to be members of the genus Mycobacterium.
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Isolation and Properties of a New Hydrogen Bacterium Related to Pseudomonas saccharophila
More LessA strain of hydrogen bacteria, phenotypically resembling Pseudomonas saccharophila, was extensively characterized. On the basis of a comparative study of the phenotypic properties of both organisms, and of DNA-DNA reannealing experiments with P. saccharophila and other species of the genus, it is concluded that the new strain is probably a member of a new species related to P. saccharophila. It is suggested that formal proposal of the new species be postponed until a larger collection of organisms of this group becomes available.
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Phenotypic and Genotypic Characterization of Some Thermophilic Species of Bacillus
More LessSome thermophilic species of Bacillus were characterized using biochemical tests, antibiotic sensitivity, bacteriocin and bacteriophage sensitivity, esterase patterns, DNA hybridization and % G+C content. The three caldo-active strains of bacilli isolated by Heinen (1971) were compared with strains of B. stearothermophilus. Eight of the strains examined showed characteristics which enabled them to be placed in the three main taxonomic groups suggested by Walker & Wolf (1971) . Two strains showed characteristics of both groups 1 and 3. Examination of genotype data showed taxonomic groupings which differed from those based on phenotypic characterization.
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