- Volume 52, Issue 1, 1968
Volume 52, Issue 1, 1968
- Article
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The Influence of Metal Ion Concentrations and pH Value on the Growth of a Nitrosomonas Strain Isolated from Activated Sludge
More LessSUMMARY: A strain of Nitrosomonas europaea was isolated from activated-sludge effluent by a dilution method which readily demonstrated the presence of contaminating heterotrophs and yielded a high proportion of tubes containing pure cultures of ammonia-oxidizing bacteria. Copper, sodium, calcium and magnesium stimulated growth of pure cultures, and effects of deficiencies of these metals were demonstrated. Ethylenediaminetetra-acetic acid improved growth in the basal medium, and abolished the toxic effect of added copper; it was, however, inhibitory at low calcium concentrations. The effect of pH value on the growth of N. europaea appeared to be dependent on the metal ion content of the medium although the optimum pH value was always between 7.5 and 8. The growth rate constant in pure culture was similar to that previously observed for nitrification in Thames water, but double that previously observed for nitrification of sewage by activated sludge. The Michaelis constants for ammonia and oxygen were similar to those found for nitrification in activated sludge.
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The Carotenoids of Corynebacterium fascians Strain 2 Y
More LessSUMMARY: An analysis of the carotenoids of Corynebacterium fascians, strain 2 Y, showed the presence of 13 fractions. The main pigments identified were β-carotene, a β-carotene-like fraction (possibly β-isorenieratene), leprotene, a mono-hydroxy pigment, P 450, a second xanthophyll, P 452 and a glucoside of hydroxy-chlorobactene. The minor constituents have been identified as phytoene, phytofluene, β-zeacarotene, neurosporene, ζ-carotene, lycopene and either γ-carotene or chlorobactene. P 452 forms a purple derivative with an absorption maximum at 560 mμ in the presence of calcium salts which can be converted to the original P 452 form by treatment with traces of acid or alkali. The total carotenoid content of the organisms is estimated at between 0.5 and 0.6 mg. carotenoid/g. dry weight of organism.
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Gene Transfer in Strains of Pasteurella pseudotuberculosis
More LessSUMMARY: Pasteurella pseudotuberculosis strain 321V accepted the F'lac episome from Escherichia coli strain 23.10S and behaved as a gene donor in crosses with several different auxotrophs of P. pseudotuberculosis. Some selected donor markers were transferred at frequencies of 10−4-10−5 per donor cell while others appeared not to be transferred. Up to 40% of recombinants were Lac+. Selected recombinants showed differing unselected marker frequencies with differing selected markers; those obtained by using double marker selection showed increased unselected marker frequencies. Some alternative explanations for the origin of recombinants (syntrophic growth, mixed clones, multiple recipient reversions) were not supported by experiment.
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The Genetics and Biochemistry of Mutants of Aspergillus nidulans Resistant to Chlorinated Nitrobenzenes
More LessSUMMARY: 2,3,5,6-Tetrachloronitrobenzene (TCNB) was a more effective fungistat than pentachloronitrobenzene (PCNB) for Aspergillus nidulans. Four mutants selected for resistance to TCNB or PCNB were resistant to both these compounds and to other halogenated nitrobenzenes, diphenyl, methylene blue and brilliant cresyl green. Resistance was conferred by either of two recessive genes in linkage group III. Three of the mutants were allelic. In crosses the frequency of resistant ascospores was less than 50%. Diploids heterozygous for resistance exposed to PCNB produced fast-growing resistant haploid or homozygous diploid segregants. PCNB decreased growth more than DNA synthesis in sensitive strains but these were unaffected in resistant strains. Five times as much TCNB was extracted from the mycelium of sensitive strains than from that of resistant strains. Resistance is probably caused by an inability to take up the chemicals rather than to an ability to metabolize them.
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Chemical Composition of Cell-wall Polysaccharide of Rough Mutants of Salmonella typhimurium
More LessSUMMARY: Quantitative analyses of monosaccharide constituents of the cell-wall polysaccharide of the smooth form and rough mutants of Salmonella typhimurium were made by gas-liquid chromatography of glycitol acetates produced from acid hydrolysates of phenol+water extracts of cell-wall preparations. The presence, in varying amounts, of sugars characteristic of the S-specific repeating unit was detected in all rough mutants investigated. Definite conclusions about the core structure of the different rough mutants could not be drawn by using only the basis of the monosaccharide composition of the cell-wall polysaccharide. Ribose was found in the cell-wall polysaccharide of the smooth form in small amounts.
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Immunochemical Studies on Cell-wall Polysaccharide of Rough Mutants of Salmonella typhimurium
More LessSUMMARY: Immunological studies were made in order to characterize the lipopolysaccharides of rough mutants of Salmonella typhimurium and S. minnesota. Groups of mutants, specified by their phage pattern, also showed group homogeneity with respect to their immunological specificity, especially when using the passive haemagglutination inhibition technique. Cross-reactions between mutants belonging to different phage groups could generally be explained on the basis of the carbohydrate composition of the lipopolysaccharide.
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Histochemical Demonstration of Certain Hydrolytic Enzymes within Cytoplasmic Particles of Botrytis cinerea Fr.
More LessSUMMARY: Established histochemical methods were used to locate the activities of several acid and neutral hydrolases within cytoplasmic particles of Botrytis cinerea Fr. The Gomori procedure revealed acid phosphatase activity and this was used as a marker to show that these particles in fresh material were inactive until subjected to treatments which affected the permeability of lipid-protein membranes. This behaviour was interpreted as indicating that these particles may be comparable with the lysosomes of animal cells. It was shown that acid phosphatase, acid deoxyribonuclease II, β-galactosidase and several esterases were localized within these particles. Attempts to demonstrate β-D-glucuronidase activity were unsuccessful; aryl sulphatase activity was weak.
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Serological Relationships of Corynebacteria
More LessSUMMARY: The serological relationships between 39 strains of pathogenic corynebacteria from man, animals and plants were studied by precipitin, double gel-diffusion, and immuno-electrophoretic techniques, with polysaccharides and nucleoproteins as antigens. Five distinct serological groups were established among the plant pathogenic corynebacteria: (1) Corynebacterium flaccumfaciens, C. flaccumfaciens var. aurantiacum, C. poinsettiae and C. betae; (2) C. michiganense and C. insidiosum. (3) C. tritici and C. rathayi; (7) C. sepedonicum; and (5) C. facians. C. diphtheriae (type gravis, mitis, intermedius, and atypical forms), C. hoffmanii, (syn. C. pseudodiphtheriticum) and the animal pathogens C. equi, C. renale and C. kutscheri belonged to two or three serological groups. The plant pathogen C. fascians appeared to occupy an intermediate position between the plant and animal pathogens, and shared many antigens in common with the plant pathogens in group 1 and the animal pathogens. Other cross-relationships were detected between the groups. An immuno-electrophoretic study was made of protein fractions from the plant pathogenic bacteria.
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The Involvement of Cellulase and Laminaranase in the Formation of Pythium Protoplasts
More LessSUMMARY: Five inducible streptomycete lytic enzyme complexes were equally capable of producing protoplasts from a Pythium sp. strain PRL 2142, when compared on a quantitative basis. Both cellulase and laminaranase from various microbial sources were required to produce the protoplasts under standard conditions. Protease was not required; lipase shortened the survival time of protoplasts. It was concluded from an analysis of the products of enzymic hydrolyses that Pythium sp. PRL 2142 cell wall contained cellulose, β-D-(1→3) glucan, and a β-D-(1→3) glucan possessing D-glucose units attached by β-(1→6)-linkages.
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The Effect of Aerosolization upon Survival and Potassium Retention by Various Bacteria
More LessSUMMARY: Previous studies with populations of Escherichia coli strain B, recovered from aerosols, showed that, of the biochemical changes which were shown to precede death, the most dramatic was a rapid loss of ability to maintain cellular potassium concentrations. Loss of control over potassium may cause or contribute to death in bacteria recovered from aerosols and also probably implies a loss of control over other ions and substrates. Potassium ion efflux studies with this organism have been extended here to E. coli var. communis, E. coli strain JEPP, Aerobacter aerogenes strain H, Serratia marcescens strain 8 UK and Staphylococcus epidermidis strain NCTC 7291. After aerosolization all these organisms rapidly lost ability to retain intracellular potassium, as a consequence of damage initiated in the aerosol. Evidence for a positive correlation between survival and potassium retention was found over a limited range of conditions for most of the organisms examined. The significance of these results in relation to death processes in aerosolized bacteria is discussed.
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A Staphylococcal Toxic Complex Affecting Particular Areas of the Mitochondrial Electron Transport System
More LessSUMMARY: Mitochondrial respiration can be impaired in vitro by a toxic complex, termed succinic oxidase factor (s.o.f.), produced by 70% of coagulase-positive staphylococci. The oxidation of succinate is most sensitive, cytochrome oxidase less so while succinic dehydrogenase is resistant. The complex consists of at least two components, differing in degree of heat sensitivity. The more heat-resistant component impairs electron transfer in the region of ubiquinone (ubiquinone can reverse the impairment), while the other component impairs electron transfer in the region of cytochrome c (cytochrome c can reverse the impairment). It is thought that the components of s.o.f. may be of enzymic nature, acting on the phospholipids responsible for the integrity of the electron transport chain.
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Identification of Mycoplasmas of Human Origin
Hava Haas, T. G. Sacks and S. RazinSUMMARY: Fifty-five strains of the genus Mycoplasma were isolated from sputam of 95 patients suffering from various respiratory tract diseases. The polyacrylamide gel electrophoretic method was used to identify the isolated strains, in addition to the conventional biochemical methods and growth-inhibition by antisera. The electrophoretic patterns of the isolated strains were compared with those of known human mycoplasmas. The electrophoretic patterns obtained were species specific and highly reproducible. The results of the identification of the isolated strains by the gel electrophoretic method correlated well with those of the growth inhibition test. It is suggested that polyacrylamide gel electrophoresis of whole cell proteins might become a useful routine method for identification of mycoplasmas.
The most prevalent Mycoplasma found in the sputa was Mycoplasma salivarium, only four strains were identified as M. orale type 1 and one strain as M. pneumoniae. One strain was similar to, but not identical with, M. salivarium. The three oral anaerobic mycoplasmas (M. salivarium, M. orale types 1 and 2) showed a certain similarity when examined by the gel electrophoretic method, they may be genetically related to each other.
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Free Endotoxin and Non-toxic Material from Gram-negative Bacteria: Electron Microscopy of Fractions from Escherichia coli
More LessSUMMARY: Toxic and non-toxic fractions, isolated from culture supernatant fluids or from organisms of Escherichia coli O78 K 80, were examined with the electron microscope after negative staining with phosphotungstate. Preparations of endotoxin from the supernatant fluids (‘free endotoxin’) contained large numbers of rod-like particles, considered to be the native undegraded endotoxic lipopolysaccharide-protein complex. Phenol-water extraction of either free endotoxin particles or whole organisms caused aggregation of the complex, leading to chain-like structures. Both ‘rods’ and ‘chains’ were observed in an endotoxin preparation extracted from organisms by aqueous ether. A non-toxic predominantly polysaccharidic preparation from E. coli was not visible after negative staining; but this fraction, and to a lesser extent the toxic fractions derived from culture supernatant fluids, were found to contain well-defined fragments believed to be derived from the bacterial cell wall.
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The Catabolism of Acyclic Polyols by Yeasts
More LessSUMMARY: Eight polyols were employed in turn as sole carbon source for aerobic growth tests with sixteen yeasts. The yeasts studied varied from those using none to others using all the polyols. Mean generation times in aerated, liquid, shaken medium for five yeasts and four polyols, were from 2 to 7.5 hr.
With seven yeasts, oxygen uptake was measured for different polyols as sole carbon source, of washed, starved yeast cells, harvested in the exponential phase of growth. No yeast respired a substrate on which it did not grow, or vice versa. Except when glucose, erythritol or galactitol (dulcitol) were employed, respiration rates were not greatly affected by the carbon source for growth.
Coenzyme-linked polyol dehydrogenase activity was measured with crude cell-free extracts of four yeasts and several polyols or sugars. The enzymes had a low affinity for their substrates. In certain cases the polyol oxidation products were examined chromatographically.
The polyol dehydrogenases of four yeasts were separated from crude cell extracts by gel electrophoresis, and detected on the gels by their activity with different polyols, and with NAD+ or NADP+. One strain of Torulopsis candida appears to synthesize at least eight polyol dehydrogenases which differ in their specificity for polyols, coenzyme or inducer. Similarly, four polyol dehydrogenases were found in a strain of Candida utilis. Most of these enzymes were inducible.
There was no evidence that phosphorylation was the first step in polyol catabolism.
From experiments with 14C-labelled polyols, it seems that Candida utilis and Pichia membranaefaciens do not utilize D-glucitol (sorbitol) or D-mannitol because these substrates do not enter the yeast cells.
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- Corrigendum
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