- Volume 122, Issue 1, 1981
Volume 122, Issue 1, 1981
- Biochemistry
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Formation of Enzymes of Autotrophic Metabolism During Heterotrophic Growth of Alcaligenes eutrophus
More LessAlcaligenes eutrophus strain H16 formed key enzymes of autotrophic metabolism during heterotrophic growth. The formation of the soluble and membrane-bound hydrogenases, ribulose-5-phosphate kinase and ribulosebisphosphate carboxylase were investigated. In addition, selected enzymes shared by autotrophic and heterotrophic carbon metabolism were examined. Key enzymes of autotrophic metabolism were not detected during exponential growth on succinate, pyruvate or acetate, but were found at intermediate activities in cells grown on fructose, gluconate or citrate. Growth with succinate at a suboptimal pH of 7·7 resulted in a decreased growth rate and a marked increase of enzyme activities. Oxygen-limited growth with succinate also led to a derepression of the synthesis of the hydrogenases and the key enzymes of the Calvin cycle. During growth on glycerol or formate, the activities of these enzymes were comparable with those found under autotrophic conditions with H2 and CO2.
The results indicate that both the hydrogenases and the key enzymes of the Calvin cycle were formed under conditions of limited availability of energy. Molecular hydrogen was not required for the formation of the hydrogenases. The regulation of the gluconeogenetic enzymes, common to both autotrophic and heterotrophic carbon metabolism, was more balanced. An increase of enzyme activities was observed under autotrophic conditions, in accord with the physiological role of these enzymes under autotrophic and heterotrophic growth conditions.
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Characterization of Two Mutant Strains of Saccharomyces cerevisiae Deficient in Coproporphyrinogen III Oxidase Activity
More LessTwo new haem-deficient Mutants of Saccharomyces cerevisiae were isolated on the basis of their catalase deficiency. Mutant H11 accumulated and excreted coproporphyrin III and was completely deficient in haem; the cell-free extract had no coproporphyrinogen oxidase activity. Mutant H12 accumulated uroporphyrin to coproporphyrin III and excreted coproporphyrin III, and contained a small amount of haem; the cell-free extract had a residual coproporphyrinogen oxidase activity. The two mutations were allelic and the mutant phenotypes were under the control of a single, recessive nuclear gene.
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The Effect of Age on the Properties of Poly(A)-containing Messenger RNA in Physarum polycephalum
More LessThe effect of ageing on the properties of polysomal poly(A)-containing messenger RNA [poly(A)+ mRNA] of Physarum polycephalum has been investigated. Using poly(U)-Sepharose affinity chromatography it was shown that shortening of the poly (A) tract occurred as the age of the mRNA population increased. Analysis of the poly(A) segments by use of polyacrylamide gel electrophoresis, after digestion of polysomal poly(A) + mRNA molecules with RNAase A and RNAase T1, revealed that their lengths ranged from 140 to 220 nucleotide residues. A reduction in the efficiency of utilization of mRNA for translation as the age of the mRNA population increased was demonstrated by measuring the proportion of poly(A)+ mRNA present in the polysomal fraction as compared with post-polysomal material.
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- Development And Structure
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Production and Chemical Composition of Extracellular Polysaccharides of Rhizobium
More LessFive cultures of Rhizobium meliloti (J7017, 202, 204, 207, 209) and one of Rhizobium trifolii (J60) produced water-soluble polysaccharides containing glucose, galactose and pyruvic acid in a molar ratio of 7:1:1 and some succinic and acetic acids. These were identified as succinoglycan-like polysaccharides on the basis of their components, methylation analysis and fragmentation with two specific β-glycanases. One culture of R. meliloti (IFO 13336) produced water-soluble polysaccharide containing glucose, galactose, glucuronic acid and acetic acid in a molar ratio of 5:1:1:2, and an unidentified component. Two cultures of R. meliloti (201, 206) produced water-soluble polysaccharides containing glucose, galactose, mannose and glucuronic acid in a molar ratio of 4:2:3:1 and 4:1:2:1, respectively, and some pyruvic acid. Rhizobium trifolii IFO 13337 and R. japonicum IFO 13338 produced water-soluble polysaccharides containing glucose, galactose, glucuronic acid, pyruvic acid and acetic acid in a molar ratio of 6:1:1:2:1. Two isolates from the stock culture of R. trifolii J60 produced large amounts of the water-insoluble polysaccharide curdlan. This is the first report in Rhizobium of the occurrence of curdlan and of spontaneous mutation in ability to produce succinoglycan-like polysaccharide and curdlan.
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Pyrolysis Mass Spectrometry of Whole Cells, Cell Walls and Isolated Cell Wall Polymers of Bacillus subtilis var. niger WM
More LessBacillus subtilis var. niger WM was grown in continuous culture under phosphate-limited and under magnesium-limited conditions. Whole cells, cell walls and the isolated wall polymers peptidoglycan, teichoic acid and teichuronic acid were analysed by Curie-point pyrolysis mass spectrometry. Characteristic ion peaks for the wall polymers were established and facilitated the interpretation of the mass pyrograms of walls and whole cells. The mass pyrograms of magnesium-limited cells showed the characteristic peaks for protein, peptidoglycan and teichoic acid. Phosphate-limited cells showed peaks characteristic of teichuronic acid instead of teichoic acid.
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- Ecology
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Effects of Fungi on Barley Seed Germination
More LessBarley seeds placed in contact with straw buried in soil imbibed water more slowly and had a greater fungal biomass under the husk at germination than did seeds which had been in contact with soil only. The growth of fungi under the husk increased during imbibition and continued when the seed was fully imbibed; such growth resulted in poor seed germination. A common soil saprophyte. Gliocladium roseum . inoculated on to the outer surfaces of the seed husk, suppressed germination by competing with the embryo for available oxygen. The prevention of seed germination by some micro-organisms seems to be related to the microbial affinity for oxygen.
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- Genetics And Molecular Biology
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Naturally Occurring Diploid Isolates of Aspergillus nidulans
More LessSix wild isolates belonging to heterokaryon compatibility group A of the Birmingham Aspergillus nidulans collection were shown to be diploid. Five were proven heterozygous for a naturally occurring conditional lethal haploid genotype. It is considered unlikely that these diploids arose by mutation in storage. Consequendy, somatic diploidy is a regular occurrence in the natural population of this saprophytic species.
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Pleiotropic Compensation in the Regulation of Extracellular Protein Formation by a Low α-Toxin-producing Variant of Staphylococcus aureus (Wood 46)
More LessThe changes in bacterial density, total extracellular protein and haemolysin produced by bacteria from overnight cultures of Staphylococcus aureus (Wood 46) and a low α-toxin-producing variant suspended in fresh medium were followed at 37 °C. Although five extracellular proteins were produced at a reduced level by the variant (α-toxin formation was reduced more than tenfold), the differential rates of total extracellular protein formation by the two organisms were identical. The results are consistent with a common regulatory mechanism for extracellular protein formation in which a pleiotropic compensation may occur in order to saturate the extracellular protein-producing capability.
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- Medical Microbiology
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Immunological Analysis of the EDTA-soluble Antigens of Clostridium difficile and Related Species
More LessAntigens were extracted with EDTA from 32 strains representing 10 species of Clostridium . When these antigens were examined by an enzyme-linked immunosorbent assay, marked cross-reactions were observed between C. difficile, C. sordellii and C. bifermentans . The cross-reactive antigen, visualized by crossed immunoelectrophoresis, was carbohydrate.
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The Role of Calf Serum in the Growth of Chlamydia trachomatis in McCoy Cell Cultures
More LessChlamydia trachomatis is normally grown in McCoy monolayer coverslip cultures using partially defined media containing foetal calf serum at concentrations up to 10% (v/v). Omission of the serum decreased the number of inclusions produced by infecting the McCoy cells with a standard inoculum of a genital strain of C. trachomatis . Substitution of the foetal calf serum with a macromolecular fraction from the serum or with a mixture of sodium oleate, bovine serum albumin fraction V and fetuin maintained the inclusion count, but substitution with serum filtrate, containing the amino acids and other low molecular weight components, decreased the inclusion count of C. trachomatis . The role of calf serum and the need for a fully defined medium excluding serum for studying the growth of C. trachomatis in tissue culture are discussed.
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- Physiology And Growth
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Carotenoid Composition and Function in Nitrogen-fixing Bacteria of the Genus Azospirillum
More LessFour different carotenoids were isolated and purified from membranes of the N2-fixing bacterium Azospirillum brasilense strain Cd, grown under aerobic conditions, and one from strain Cd-1. Carotenoid synthesis did not occur under microaerobic conditions. Cells of these strains formed aggregates (>0·1 mm in diameter) when subjected to aerobic conditions. Neither carotenoids nor cell aggregation were observed in A. brasilense strains Sp 7, Sp81 and Sp51e. All of the differently pigmented Azospirillum strains tested contained similar amounts of soluble cytochrome c. In the presence of diphenylamine, which specifically inhibits carotenoid synthesis, the rate of acetylene reduction (N2 fixation) in strain Cd decreased to 50% of the control. Carotenoid synthesis was inhibited in cells grown in the presence of NH4Cl at concentrations higher than 10 mm. Carotenoid synthesis started in liquid cultures of suain Cd only after the concentration of NH4Cl in the medium decreased, and N2 fixation became evident at the same time. In comparison, strain Sp81 did not grow or fix nitrogen after NH4Cl was depleted. Carotenoids appear to protect the nitrogenase of A. brasilense strains Cd and Cd-1 from oxidative damage.
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Properties of Tn5-induced Carbohydrate Mutants in Rhizobium meliloti
More LessCarbohydrate mutants were isolated from Rhizobium meliloti L5-30 using the translocatable drug-resistance element Tn5. Enzyme assays with cell-free extracts of four mutants showed that they lacked mannitol dehydrogenase, ribose kinase, xylose isomerase and fructose kinase, respectively. An l-arabinose mutant was also isolated. Uptake studies showed that the ribose, xylose and fructose mutants still utilized the sugars on which they were unable to grow, possibly indicating that R. meliloti possesses alternative metabolic routes which do not result in growth. All the mutants were able to nodulate alfalfa plants, but the fructose kinase mutant was unable to fix nitrogen and the l-arabinose mutant showed either late or no nitrogen-fixing ability.
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Ribulose-1,5-bisphosphate Carboxylase/Oxygenase and Carbon Assimilation in Methylococcus capsulatus (Bath)
More LessIntact cells of chemostat-grown Methylococcus capsulatus (Bath) assimilated CO2 such that approximately 2.5% (w/w) of cell carbon arose from CO2 during growth with methane as carbon substrate. Radiolabelling studies suggested that CO2 was fixed by both ribulose-1,5-bisphosphate (RuBP) carboxylase and known heterotrophic mechanisms. The pattern of CO2 fixation was similar to that in heterotrophically grown autotrophs. Enzyme analysis suggested the presence of a complete Calvin cycle but attempts to grow the organism autotrophically were unsuccessful. A specific phosphoglycollate phosphatase, required for the metabolism of phosphoglycollate arising as a result of RuBP oxygenase activity, was present. The product of this reaction, glycollate, was further metabolized by reactions of the serine cycle, used for C1 assimilation in type II methylotrophs. The possession of this pathway explains both the presence of hydroxypyruvate reductase and the results of [14C]formate uptake reported by other workers. The relationship between RuBP carboxylase/oxygenase and net carbon assimilation is discussed.
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Repression of β-Ureidopropionase by Ammonia in Rhodopseudomonas capsulata
More LessThe overall rate of reductive pyrimidine degradation in Rhodopseudomonas capsulata R10 was limited during growth with an excess of uracil as sole exogenous nitrogen source. β-Ureidopropionase was the rate-limiting step in the degradative pathway. The synthesis of this enzyme was repressed by ammonia, which accumulated during uracil degradation, while dihydrouracil dehydrogenase was induced in the presence of its substrate. It is postulated that β-ureidopropionase may not be specific for reductive pyrimidine degradation.
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Growth Characteristics of Saccharomyces cerevisiae and Aspergillus nidulans when Biotin is Replaced by Aspartic and Fatty Acids
More LessWhen either aerobic or anaerobic cultures of Saccharomyces cerevisiae were supplemented with aspartic and fatty acids in place of biotin, stationary phase populations were very small compared with those obtained in the presence of biotin. Similarly, these acids failed to fulfil the role of biotin in a biotin-requiring strain of Aspergillus nidulans . Furthermore, a requirement for saturated fatty acid was found with anaerobically cultured S. cerevisiae . Cells were fragmented when biotin was replaced by aspartic and oleic acids alone, while cellular integrity was maintained, but with only slight growth, when biotin was replaced by oleic and palmitic acids together with aspartate. The importance of biotin in the growth of A. nidulans was particularly pronounced in the presence of glucose. In a medium containing glucose, growth ceased when biotin was replaced by aspartate and Tween 80 (a source of saturated and unsaturated fatty acids), but such replacement permitted a very small amount of growth to occur in the absence of glucose.
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A Continuous Culture Study of Growth of Bacillus cereus T
More LessGrowth of an oligosporogenic strain of Bacillus cereus T was studied in continuous culture. The maximum specific growth rate obtained was 0·47 h−1. RNA content increased linearly with increasing growth rate. Protein content decreased at high growth rates, but the DNA content of the culture was not affected by the growth rate. Activities of enzymes involved in glutamate utilization and energy production increased with increasing growth rate. The maximum specific activity for all enzymes assayed was obtained at a dilution rate of about 0.30 h−1. Changing the concentration of zinc or manganese in the medium by as little as 10−7 M from the concentration optimum for growth caused a significant reduction in the steady-state bacterial population. Zinc appeared to affect the efficiency of conversion of substrate to biomass. Manganese was very toxic at concentrations slightly above the concentration optimum for a specific growth rate.
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The Potential for the Formation of Sclerotia in Submerged Mycelium of Sclerotium rolfsii
More LessSynchronous formation of sclerotia in Sclerotium rolfsii was induced in both solid and liquid synthetic media. Sclerotial initials were formed when mycelium was forced to pass from the submerged to the aerial growth phase in one of the following ways: (i) by removal of aerial mycelium with a scalpel; (ii) by growing the mycelium under a cover glass which was later removed; (iii) by inverting the agar in a Petri dish containing the fungal culture; (iv) by pouring a layer of agar over a colony. In all cases hyphae which emerged from the submerged phase produced many sclerotia synchronously. When grown in shaken liquid culture S. rolfsii did not produce any sclerotia while submerged, but when samples of the shaken culture were poured into a Petri dish 50 to 90 h after inoculation and incubated further, sclerotial initials were formed synchronously within 16 h on the liquid surface.
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- Short Communication
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A Correlation between in Vivo and in Vitro Effects of the Microtubule Inhibitors Colchicine, Parbendazole and Nocodazole on Myxamoebae of Physarum polycephalum
More LessThe effects of the microtubule inhibitors colchicine, parbendazole and nocodazole on the growth of myxamoebae of Physarum polycephalum were closely paralleled by the effects of these drugs on the assembly in vitro of purified amoebal microtubule protein. Colchicine at 100 µ m did not inhibit amoebal growth and did not inhibit formation, or depolymerization, of amoebal microtubules. The benzimidazole carbamate derivatives nocodazole and parbendazole were very effective in both inhibiting growth and inhibiting the assembly in vitro of amoebal microtubule protein. Parbendazole was the most effective.
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Duplication Cycle in Filamentous Forms of Saccharomyces cerevisiae
More LessSaccharomyces cerevisiae strain S288C/1 was grown in a glucose-limited chemostat. At the fastest growth rates filamentous forms constituted a small percentage of the total cell number and were presumed to arise from the failure of cells to undergo cell separation. The phenomenon seemed to be distinct from chain formation, dimorphism and pseudomycelial growth and showed extensive analogies with the duplication cycle described for the filamentous fungi.
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Phage C-1: an IncC Group Plasmid-specific Phage
More LessA phage was isolated from sewage and shown to form plaques on Salmonella typhimurium strains carrying C plasmids. It failed to multiply on strains lacking plasmids of this group. It also plated on Proteus mirabilis and Serratia marcescens strains carrying various IncC plasmids but failed to form plaques on Escherichia coli strains harbouring most of these plasmids, although in all cases, phage multiplication on the strains was demonstrated. No phage increase occurred in any of the strains which lacked an IncC plasmid or contained plasmids of other incompatibility groups. The phage is small, hexagonal in outline, contains RNA, is resistant to chloroform and adsorbs to the shafts of pili coded for by IncC plasmids.
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Plasmids and Phaseolotoxin Production in Pseudomonas syringae pv. phaseolicola
More LessNo correlation was found between phaseolotoxin production and the presence of any one plasmid in twelve Pseudomonas syringae pv. phaseolicola strains. The spontaneous loss of ability to produce phaseolotoxin by three of these strains was not associated with loss of a specific plasmid.
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Correlation Between Isocitrate Dehydrogenase Activity and Glutamate Excretion by Citrobacter intermedius C3
More LessGlutamic acid was excreted by Citrobacter intermedius strain C3. which carries the extrachromosomal S factor, but not by strains lacking S factor. There was a correlation between the isocitrate dehydrogenase activity of cell-free extracts and the rate of glutamate excretion by various strains. Differences were detected in the Km for isocitrate, the specific activity and stability of isocitrate dehydrogenase from strains CBC356 and C3 which differ in their ability to excrete glutamate. We suggest that the S factor plasmid is required for isocitrate dehydrogenase synthesis in C. intermedius C3 and that this enzyme plays an important role in the regulation of glutamate excretion.
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- Taxonomy
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Characterization of Strains of Clostridium puniceum sp.no v., a Pink-pigmented, Pectolytic Bacterium
More LessThe properties of ten strains of pink-pigmented, pectolytic clostridia implicated in spoilage of potatoes and one strain isolated from carrots have been compared with reference strains. On the basis of the position of spore formation, ability to degrade gelatin, and formation of butanol plus acetic and butyric acids, the organisms resemble Clostridium acetobutylicum, C. aurantibutyricum and C.felsineum , but they differ sufficiently from these bacteria to warrant recognition as a new species.
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Pyrolysis Mass Spectrometry: A New Method to Differentiate Between the Mycobacteria of the “Tuberculosis Complex” and Other Mycobacteria
More LessPyrolysis mass spectrometry (p.m.s.) was applied to differentiate 91 coded mycobacteria as belonging to either the ‘tuberculosis complex’ ( M. tuberculosis, M. bovis and M. bovis BCG) or to other species of Mycobacterium . Strains were analysed in batches; in each batch three strains each of M. tuberculosis, M. bovis and M. bovis BCG were included as references. Mass spectra were evaluated by computerized multivariate analysis. A 92% positive correlation with classical identification tests was found (2·2% false negative, 5·5% false positive). Approaches for further improvement of this score are indicated. High speed and complete automation of sample analysis, as well as computerized data-processing, make p.m.s. a potential tool for routine application. Sample transfer from peripheral laboratories to a p.m.s. facility is easy, as samples can be sterilized before shipping.
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Volumes and issues
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