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Volume 42,
Issue 1,
1966
Volume 42, Issue 1, 1966
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Inhibition by o-Aminoazotoluene of the Incorporation of Certain Radioactive Amino Acids into Lipids of Mycobacterium Smegmatis
More LessSUMMARY: A carcinogenic substance, o-aminoazotoluene (AAT), inhibited the incorporation of [1-14C]glycine and [1-14C]leucine into the lipid fraction of Mycobacterium smegmatis. It inhibited transiently the incorporation of [1-14C]glutamic acid into lipids, but it did not inhibit the incorporation of [1-14C]acetate into lipids. AAT did not inhibit the incorporation into the protein and nucleic acid fractions of [1-14C]glycine, [1-14C]leucine, [1-14C]glutamic acid, and [1-14C]acetate.
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Inhibition by o-Aminoazotoluene of the Incorporation of Certain Radioactive Amino Acids into Lipids of Mycobacterium Smegmatis
More LessSUMMARY: A carcinogenic substance, o-aminoazotoluene (AAT), inhibited the incorporation of [1-14C]glycine and [1-14C]leucine into the lipid fraction of Mycobacterium smegmatis. It inhibited transiently the incorporation of [1-14C]glutamic acid into lipids, but it did not inhibit the incorporation of [1-14C]acetate into lipids. AAT did not inhibit the incorporation into the protein and nucleic acid fractions of [1-14C]glycine, [1-14C]leucine, [1-14C]glutamic acid, and [1-14C]acetate.
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Mycobacterium Parafortuitum: a New Species
More LessSUMMARY: A new species Mycobacterium parafortuitum is described. A number of strains of the genus Mycobacterium isolated from soil resembled M. fortuitum in their rapid growth, in their pattern of utilization of organic acids and in their pattern of amidase tests. However, these strains differed from M. fortuitum in the following points: they showed negative 3-day aryl-sulphatase test, they showed negative salicylate degradation and PAS degradation, they did not utilize nitrite as sole nitrogen source, and they formed acid from pentoses, arabinose, xylose, inositol and mannitol. This group of strains has been named as M. parafortuitum sp.nov.
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Mycobacterium Parafortuitum: a New Species
More LessSUMMARY: A new species Mycobacterium parafortuitum is described. A number of strains of the genus Mycobacterium isolated from soil resembled M. fortuitum in their rapid growth, in their pattern of utilization of organic acids and in their pattern of amidase tests. However, these strains differed from M. fortuitum in the following points: they showed negative 3-day aryl-sulphatase test, they showed negative salicylate degradation and PAS degradation, they did not utilize nitrite as sole nitrogen source, and they formed acid from pentoses, arabinose, xylose, inositol and mannitol. This group of strains has been named as M. parafortuitum sp.nov.
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Continuous Culture of Yeast on Phenol
More LessSUMMARY: Debaryomyces subglobosus (NCYC 459) was grown in continuous culture at 30° in media containing 3, 6.65, 9 and 12 μmoles phenol/ml. as sole source of carbon. With each medium, wash-out of organisms occurred at dilution rates in the range 0.33-0.36 hr-1. The yeasts became quickly adapted to the medium with lowest phenol content and grew readily at dilution rates between 0.1 and 0.3 hr-1. At lower dilution rates, however, the endogenous metabolism of the yeasts tended to outstrip the rate at which phenol was supplied. With 9 μmoles phenol/ml. the best rate of output of yeast was achieved but at 6.65 μmoles phenol/ml., was most fully utilized, utilization being complete up to a dilution rate of 0.3 hr-1. At the highest contents of phenol in the medium, the yeast adapted less readily and produced considerable amounts of riboflavin. The population became heterogeneous, with some yeasts clumping and other large and fragile. There was some evidence that the latter were unable to metabolize phenol but could utilize catechol, a product of metabolism of the normal organisms.
The appendix provides a comparison between the reported results and those calculated from the growth constants using classical mathematical treatment of continuous culture. Substantial deviations are attributed to high maintenance energy requirements, flocculation of the yeast and toxicity of the medium.
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Continuous Culture of Yeast on Phenol
More LessSUMMARY: Debaryomyces subglobosus (NCYC 459) was grown in continuous culture at 30° in media containing 3, 6.65, 9 and 12 μmoles phenol/ml. as sole source of carbon. With each medium, wash-out of organisms occurred at dilution rates in the range 0.33-0.36 hr-1. The yeasts became quickly adapted to the medium with lowest phenol content and grew readily at dilution rates between 0.1 and 0.3 hr-1. At lower dilution rates, however, the endogenous metabolism of the yeasts tended to outstrip the rate at which phenol was supplied. With 9 μmoles phenol/ml. the best rate of output of yeast was achieved but at 6.65 μmoles phenol/ml., was most fully utilized, utilization being complete up to a dilution rate of 0.3 hr-1. At the highest contents of phenol in the medium, the yeast adapted less readily and produced considerable amounts of riboflavin. The population became heterogeneous, with some yeasts clumping and other large and fragile. There was some evidence that the latter were unable to metabolize phenol but could utilize catechol, a product of metabolism of the normal organisms.
The appendix provides a comparison between the reported results and those calculated from the growth constants using classical mathematical treatment of continuous culture. Substantial deviations are attributed to high maintenance energy requirements, flocculation of the yeast and toxicity of the medium.
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Numerical Taxonomy of Bacteria — Some Published Data Re-examined
More LessSUMMARY: A probabilistic similarity index has been calculated from published data for the genera Chromobacterium and Mycobacterium, and for the Enterobacteriaceae. The resulting similarity matrices have been used as a basis for classification with significance tests.
The results show very good general agreement with the original analyses using simple Jaccard similarity indices, but the new index has proved rather more sensitive, and has enabled certain additional subdivisions to be made.
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Numerical Taxonomy of Bacteria — Some Published Data Re-examined
More LessSUMMARY: A probabilistic similarity index has been calculated from published data for the genera Chromobacterium and Mycobacterium, and for the Enterobacteriaceae. The resulting similarity matrices have been used as a basis for classification with significance tests.
The results show very good general agreement with the original analyses using simple Jaccard similarity indices, but the new index has proved rather more sensitive, and has enabled certain additional subdivisions to be made.
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Autolytic Enzymes in Fungal Cell Walls
More LessSUMMARY: Autolytic glucanase and protease activity was detected in cell walls of some pythium species prepared by ultrasonic treatment. The glucanase activity was correlated with mycelial development. Maximal glucose release was detected in growing cultures during the linear growth period of the fungus. Assays of glucanase activity in cell walls prepared from mycelium harvested at different times showed that the enzymic activity increased with the age of mycelium from which the cell walls were prepared. The relationship between autolytic enzymes and mycelial development is discussed.
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Autolytic Enzymes in Fungal Cell Walls
More LessSUMMARY: Autolytic glucanase and protease activity was detected in cell walls of some pythium species prepared by ultrasonic treatment. The glucanase activity was correlated with mycelial development. Maximal glucose release was detected in growing cultures during the linear growth period of the fungus. Assays of glucanase activity in cell walls prepared from mycelium harvested at different times showed that the enzymic activity increased with the age of mycelium from which the cell walls were prepared. The relationship between autolytic enzymes and mycelial development is discussed.
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DNA Homology and Taxonomy of Pseudomonas and Xanthomonas
More LessSUMMARY: The relatedness between several nomen species of the Pseudomonas-Xanthomonas group and some other organisms was numerically fixed through DNA homology and DNA base composition. For Pseudomonas the numerically analysed strains proposed by Lysenko as neotypes were used. The mean % (G+C) was in the range 60-67.5. 14C-DNA from either Pseudomonas fluorescens or P. putida was hybridized with DNA from 17 different species centres and the DNA homology was in the range 50-100%. Genetic species differentiation in the genus Pseudomonas seems justified. In three border cases (P. iodinum, P. diminuta and P. atlantica) DNA homology was only 28-50%, so the inclusion of these organisms in the genus Pseudomonas is uncertain. The species centres P. pavonacea and P. rubescens are omitted from the genus Pseudomonas because of their very low DNA homology and aberrant DNA base composition. Twenty-eight nomen species of Xanthomonas all form a narrow group in the range 63.5-69% (G+C). With two exceptions DNA homology with a median strain Xanthomonas pelargonii was always over 75% and frequently nearly complete. 14C-DNA from P. fluorescens hybridized with Xanthomonas-DNA to the same extent as with the pseudomonads proper. The Xanthomonas cluster overlapped perfectly with part of the Pseudomonas group. It is proposed therefore to gather all xanthomonads in a single genetic species P. campestris. This is such a dense cluster that the preservation of separate species names for the border cases seems undesirable. About one half to two-thirds of Pseudomonas- and Xanthomonas-DNA is identical. The genera Rhizobium, Azotobacter and Azomonas appeared to be rather closely related to Pseudomonas since they shared some 40-50% of their DNA. The genus Serratia appeared to be more closely related to Pseudomonas than to Escherichia. The genera Gluconobacter, Acetobacter, Serratia and Escherichia shared some 20-30% DNA with Pseudomonas, but Bacillus-DNA was almost entirely different. From a comparison between DNA homology and taximetric similarity, it appeared that most pseudomonads would not contain unused genes. The advantages of a classification based on % (G+C) and DNA homology are obvious.
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DNA Homology and Taxonomy of Pseudomonas and Xanthomonas
More LessSUMMARY: The relatedness between several nomen species of the Pseudomonas-Xanthomonas group and some other organisms was numerically fixed through DNA homology and DNA base composition. For Pseudomonas the numerically analysed strains proposed by Lysenko as neotypes were used. The mean % (G+C) was in the range 60-67.5. 14C-DNA from either Pseudomonas fluorescens or P. putida was hybridized with DNA from 17 different species centres and the DNA homology was in the range 50-100%. Genetic species differentiation in the genus Pseudomonas seems justified. In three border cases (P. iodinum, P. diminuta and P. atlantica) DNA homology was only 28-50%, so the inclusion of these organisms in the genus Pseudomonas is uncertain. The species centres P. pavonacea and P. rubescens are omitted from the genus Pseudomonas because of their very low DNA homology and aberrant DNA base composition. Twenty-eight nomen species of Xanthomonas all form a narrow group in the range 63.5-69% (G+C). With two exceptions DNA homology with a median strain Xanthomonas pelargonii was always over 75% and frequently nearly complete. 14C-DNA from P. fluorescens hybridized with Xanthomonas-DNA to the same extent as with the pseudomonads proper. The Xanthomonas cluster overlapped perfectly with part of the Pseudomonas group. It is proposed therefore to gather all xanthomonads in a single genetic species P. campestris. This is such a dense cluster that the preservation of separate species names for the border cases seems undesirable. About one half to two-thirds of Pseudomonas- and Xanthomonas-DNA is identical. The genera Rhizobium, Azotobacter and Azomonas appeared to be rather closely related to Pseudomonas since they shared some 40-50% of their DNA. The genus Serratia appeared to be more closely related to Pseudomonas than to Escherichia. The genera Gluconobacter, Acetobacter, Serratia and Escherichia shared some 20-30% DNA with Pseudomonas, but Bacillus-DNA was almost entirely different. From a comparison between DNA homology and taximetric similarity, it appeared that most pseudomonads would not contain unused genes. The advantages of a classification based on % (G+C) and DNA homology are obvious.
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Chemistry of Hyphal Walls of Phytophthora
More LessSUMMARY: Hyphal walls of two phytopathogenic moulds, Phytophthora cinnamomi and P. parasitica, were isolated essentially free from cytoplasmic contamination. They have a complex chemical structure consisting of polysaccharide, protein and lipid. D-Glucose was the main monosaccharide detected in acid hydrolysates. Chromatographic evidence suggested the presence of small amounts of mannose (0.6%), glucosamine (0.3%) and traces of galactosamine and ribose. Glucans constituted nearly 90% of the wall but only about a maximum 25% of the wall could be regarded as cellulose I on the basis of solubility, resistance to hydrolysis and X-ray diffraction. Most of the wall glucan exhibited chemical and physical properties unlike typical cellulose.
The spectrum of amino acids commonly found in fungal walls was detected; hydrolysates also contained hydroxyproline and two minor unidentified ninhydrin-positive components. Protein comprised 3-5% of the wall. A small amount of lipid (1-3%), mostly of the bound type, was found, and also traces of phosphorus, and compounds with absorption maxima at 263 mμ. Hyphal walls of Phytophthora cinnamomi and P. parasitica differed only slightly in quantitative composition.
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Chemistry of Hyphal Walls of Phytophthora
More LessSUMMARY: Hyphal walls of two phytopathogenic moulds, Phytophthora cinnamomi and P. parasitica, were isolated essentially free from cytoplasmic contamination. They have a complex chemical structure consisting of polysaccharide, protein and lipid. D-Glucose was the main monosaccharide detected in acid hydrolysates. Chromatographic evidence suggested the presence of small amounts of mannose (0.6%), glucosamine (0.3%) and traces of galactosamine and ribose. Glucans constituted nearly 90% of the wall but only about a maximum 25% of the wall could be regarded as cellulose I on the basis of solubility, resistance to hydrolysis and X-ray diffraction. Most of the wall glucan exhibited chemical and physical properties unlike typical cellulose.
The spectrum of amino acids commonly found in fungal walls was detected; hydrolysates also contained hydroxyproline and two minor unidentified ninhydrin-positive components. Protein comprised 3-5% of the wall. A small amount of lipid (1-3%), mostly of the bound type, was found, and also traces of phosphorus, and compounds with absorption maxima at 263 mμ. Hyphal walls of Phytophthora cinnamomi and P. parasitica differed only slightly in quantitative composition.
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Flagellar Synthesis in Salmonella typhimurium: Factors Affecting the Formation of the Flagellar ε-N-Methyllysine
More LessSUMMARY: In growing cultures of Salmonella typhimurium, flagellar ε-N-methyllysine (NML) can be isotopically labelled with either L-[Me-14C]methionine or L-[U-14C]lysine. This isotopic labelling of flagellar NML was unaffected by the addition of DL-NML to the incubation medium. The methionine analogues, D-methionine and DL-ethionine, competitively inhibited the incorporation of the methyl group from methionine into flagellar NML, but had no effect on the incorporation of L-[U-14C]lysine. Although it is probable that methylation of lysine occurs after it has been incorporated into the flagellin molecule, it has not been possible by using antibiotics and purine and pyrimidine analogues to differentiate between flagellar synthesis and the formation of flagellar NML. Attempts to obtain a cell-free preparation capable of synthesizing NML have so far been unsuccessful.
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Flagellar Synthesis in Salmonella typhimurium: Factors Affecting the Formation of the Flagellar ε-N-Methyllysine
More LessSUMMARY: In growing cultures of Salmonella typhimurium, flagellar ε-N-methyllysine (NML) can be isotopically labelled with either L-[Me-14C]methionine or L-[U-14C]lysine. This isotopic labelling of flagellar NML was unaffected by the addition of DL-NML to the incubation medium. The methionine analogues, D-methionine and DL-ethionine, competitively inhibited the incorporation of the methyl group from methionine into flagellar NML, but had no effect on the incorporation of L-[U-14C]lysine. Although it is probable that methylation of lysine occurs after it has been incorporated into the flagellin molecule, it has not been possible by using antibiotics and purine and pyrimidine analogues to differentiate between flagellar synthesis and the formation of flagellar NML. Attempts to obtain a cell-free preparation capable of synthesizing NML have so far been unsuccessful.
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Characteristics of Cell Walls from Morphological Variants of Escherichia Coli
More LessSUMMARY: Two strains (E-26 and B) of Escherichia coli were examined for their growth response in a medium containing 0.75% (w/v) NaCl, 1% (w/v) L-lysine hydrochloride, 2% (w/v) glucose, 2.4% (w/v) nutrient broth, and 5% (w/v) casein hydrolysate. Strain E-26 grew as a rod which was slightly larger than when it was grown in a defined medium. Strain B grew as a filamentous and branched form; while in defined medium it grew as a rod of normal dimensions. Cell walls were isolated from both strains. Chemical analysis showed that the filamentous and branched forms had one-third the amount of hexosamine and one-fifth the amount of reducing sugar as compared with the morphologically normal form. The abnormal cell walls were more susceptible to trypsin action, more resistant to lysozyme action and more completely disaggregated by sodium dodecyl sulphate than the walls from the morphologically normal organisms.
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Characteristics of Cell Walls from Morphological Variants of Escherichia Coli
More LessSUMMARY: Two strains (E-26 and B) of Escherichia coli were examined for their growth response in a medium containing 0.75% (w/v) NaCl, 1% (w/v) L-lysine hydrochloride, 2% (w/v) glucose, 2.4% (w/v) nutrient broth, and 5% (w/v) casein hydrolysate. Strain E-26 grew as a rod which was slightly larger than when it was grown in a defined medium. Strain B grew as a filamentous and branched form; while in defined medium it grew as a rod of normal dimensions. Cell walls were isolated from both strains. Chemical analysis showed that the filamentous and branched forms had one-third the amount of hexosamine and one-fifth the amount of reducing sugar as compared with the morphologically normal form. The abnormal cell walls were more susceptible to trypsin action, more resistant to lysozyme action and more completely disaggregated by sodium dodecyl sulphate than the walls from the morphologically normal organisms.
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Studies on the Mode of Action of the Streptogramin Antibiotics
More LessSUMMARY: Streptogramin is a complex antibiotic containing two components, streptogramin A and streptogramin B. The individual components are bacteriostatic whereas the mixture is bactericidal. At growth-limiting concentrations streptogramin A and the streptogramin complex inhibit Staphylococcus aureus by blocking protein synthesis but not nucleic acid and cell wall synthesis. Protein, nucleic acid and cell wall synthesis were all reduced in the presence of streptogramin B.
Streptogramin A, but not streptogramin B, inhibits the binding of radioactive chloramphenicol to bacterial ribosomes. However, streptogramin B enhances this effect of streptogramin A in a cell-free system containing both bacterial soluble fraction and ribosomes. The results suggest that streptogramin A inhibits protein synthesis by bacteria at the ribosome level, and that this effect is enhanced by streptogramin B.
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Studies on the Mode of Action of the Streptogramin Antibiotics
More LessSUMMARY: Streptogramin is a complex antibiotic containing two components, streptogramin A and streptogramin B. The individual components are bacteriostatic whereas the mixture is bactericidal. At growth-limiting concentrations streptogramin A and the streptogramin complex inhibit Staphylococcus aureus by blocking protein synthesis but not nucleic acid and cell wall synthesis. Protein, nucleic acid and cell wall synthesis were all reduced in the presence of streptogramin B.
Streptogramin A, but not streptogramin B, inhibits the binding of radioactive chloramphenicol to bacterial ribosomes. However, streptogramin B enhances this effect of streptogramin A in a cell-free system containing both bacterial soluble fraction and ribosomes. The results suggest that streptogramin A inhibits protein synthesis by bacteria at the ribosome level, and that this effect is enhanced by streptogramin B.
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