- Volume 23, Issue 3, 1960
Volume 23, Issue 3, 1960
- Article
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Studies of the Morpholoǵical, Physioloǵical, and Biochemical Characters of Actinomyces bovis
More LessSUMMARY: A study was made of 11 bovine strains of Actinomyces. These strains were compared with 15 human strains identified as Actinomyces israelii and Actinomyces naeslundii. Ten of the bovine strains constituted a homogeneous group identified as Actinomyces bovis. One of the bovine strains was identified as A. israelii.
The characteristics of Actinomyces bovis were the following: it failed to form a true mycelium in vitro; it had less tendency than A. israelii and A. naeslundii to form mycelial elements in lesions in animals into which it was inoculated. Characteristically it formed two types of colonies when first isolated from animals and when maintained in culture. These colonies were: (1) a smooth glistening transparent microcolony having an entire or furred edge; (2) a raised, opaque, rough colony having an entire or furred edge. The microcolonies of A. bovis were very characteristic on brain heart infusion agar and were easily differentiated from the mycelial colonies of A. israelii and A. naeslundii. Variation of the morphology of the colonies occurred rapidly in vitro as a result of genetic change and the medium used. When large, on certain media, the colonies of either the rough or smooth variants were sometimes indistinguishable from colonies of A. israelii or A. naeslundii, but were easily distinguishable on brain heart infusion agar. A. bovis was a catalase negative anaerobe which did not hydrolyse gelatin or casein; but in contrast to A. israelii and A. naeslundii it hydrolysed starch rapidly and completely when tested with KI +12 solution. A. bovis produced acid but no gas from starch but did not form acid or gas from xylose, raffinose, and mannitol, and did not reduce nitrate to nitrite. A. israelii did not form acid or gas from starch; it usually produced acid but no gas from xylose and mannitol, and occasionally produced acid but no gas from raffinose; it reduced nitrate to nitrite sometimes. A. naeslundii produced no acid or gas from starch; it produced acid but no gas from raffinose but not from xylose or mannitol, and it reduced nitrate to nitrite.
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The Adaptive Deǵradation of L-Histidine by Paracolobactrum aeroǵenoides
More LessSUMMARY: The characteristics of an induced, enzyme system responsible for the degradation of l-histidine by a soil organism were studied. Induction could be achieved by exposing cells to l-histidine, d-histidine, urocanate, β-alanyl-l-histidine or l-histidyl- l-histidine, but not by exposure to a variety of other imidazoles. The kinetics of induction by l- and d-histidine differed considerably and the d-isomer was shown to be metabolized only very slowly by fully induced cells. Chloramphenicol and dl-p-fluorophenylalanine strongly inhibited enzyme synthesis, whilst a variety of purine and pyrimidine analogues were without effect. Nitrogen starvation of noninduced cells decreased but did not completely prevent the appearance of the enzyme system on induction with d-histidine. Non-induced cells possess a low level of ‘basal’ enzymes before exposure to an inducing substance.
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On Distribution of Filamentous-Cluster Orǵanisms (Krassilnikoviae) in Sea and Ocean Depths
More LessSUMMARY: The investigations carried out make it possible to conclude that filamentous- cluster organisms (Krassilnikoviae) rather form accumulations-layers at certain depths than get diffusely distributed in the sea and ocean water column. Possibly these layers occur at the junctions of water masses of different densities. The filamentous-cluster organisms have been found in all geographic zones of the world ocean, from Polar latitudes down to the equator.
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Transduction of Streptomycin Resistance in Proteus mirabilis
More LessSUMMARY: Five of eleven different temperate Proteus phages are capable of intrastrain transduction of a streptomycin resistance marker. Interstrain transduction of this marker was achieved with three of the five phages. Nuclear segregation and phenomic lag may both be involved in the delay in phenotypic expression of streptomycin resistance. The one transducing phage investigated appears to possess a normal phage genome in that transductant colonies are lysogenic and show lysogenic conversion, at multiplicities of phage input of less than 0·02, and under conditions where secondary infection on the plates can be excluded. However, under these conditions a few transductant clones were encountered which were not lysogenic. This indicates that the transducing and lysogenizing functions of this phage may be divorced from each other. Ultraviolet irradiation has a differential effect on its transducing and plaque-forming abilities.
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The Growth of Micro-organisms in Relation to their Energy Supply
More LessSummary: When Streptococcus faecalis was grown anaerobically in a complex medium containing d-glucose, d-ribose or l-arginine as energy source the dry wt. of organism produced was proportional to the concentration of the energy source in the medium. However, S. faecalis will not grow in a defined medium with arginine as the energy source unless glucose is present at the same time. The anaerobic growth of both Saccharomyces cerevisiae and Pseudomonas lindneri was proportional to the concentration of glucose in the medium and the yield coefficient—defined as g. dry wt. organism/mole glucose—of the former was the same as that of S. faecalis grown upon glucose and approximately twice that of P. lindneri. Calculation of the g. dry wt. organism/mole adenosine triphosphate synthesized for these three organisms gave values ranging from 12·6 to 8·3 with an average of 10·5. These results suggest that, under anaerobic conditions, the yield of S. faecalis, S. cerevisiae and P. lindneri was proportional to the amount of ATP synthesized. When Propionibacterium pentosaceum was grown anaerobically with glucose, glycerol or dl-lactate as energy source there was, in all three cases, a linear relationship between the dry wt. of organisms produced and the concentration of the energy source in the medium. The values of the yield coefficients obtained were compatible with the formation of approximately 4 mole ATP/mole glucose, 2 mole ATP/mole glycerol and 1 mole ATP/mole lactate.
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Some Properties of a Gram-Negative Heterotrophic Marine Bacterium
More LessSummary: Some properties of a marine bacterium are described. This organism belongs to a large, but ill-defined, group comprising Gram-negative rods with no apparent action on monosaccharides. It is a polar flagellate, has limited acid tolerance, consistent with its inability to produce acid from sugars and has no constitutive system for metabolizing glucose. A weak inducible system was available, however, which enabled adapted organisms to grow on glucose and use it as a respiratory substrate. The organism also lacks a constitutive citric acid cycle but ability to metabolize succinate was induced by growth on succinate or glucose. It cannot use inorganic nitrogen for growth. Of the compounds examined, amino acids were the most generally satisfactory sources of energy, carbon, and nitrogen. The organism accumulated a relatively large pool of intracellular amino acids which probably contributed largely to its high rate of endogenous respiration. The classification of the bacterium is discussed.
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The Synthesis of Enzymes Concerned in Bacterio-chlorophyll Formation in Growing Cultures of Rhodopseudomonas spheroides
More LessSummary: The enzymes δ -aminolaevulic acid synthetase and <5-aminolaevulic acid dehydrase are concerned in the early stages of tetrapyrrole formation; factors controlling their synthesis have been studied in cultures of Rhodopseudomonas spheroides growing exponentially. In organisms growing in the dark under high degrees of aeration the differential rate of synthesis (increase in enzyme/increase in culture density) of both enzymes is about one-third of that in cultures growing anaerobically in the light. Organisms growing in the dark under low degrees of aeration form the enzymes at rates comparable to those in photosynthetic cultures. Under anaerobic conditions the differential rate of synthesis of both enzymes is decreased by increasing the light intensity. Enzyme synthesis in the light is repressed by oxygen, the effect being overcome on restoration of anaerobic conditions. Formation of bacterio- chlorophyll under these various conditions is affected in the same way as enzyme synthesis. Addition of δ-aminolaevulic acid or haemin to growing cultures stopped the synthesis of the synthetase and the dehydrase; magnesium protoporphyrin had no such effect. The activity of the synthetase, but not of the dehydrase, was decreased in organisms growing with suboptimal concentrations of biotin. A component of the electron transport chain as well as the intracellular concentration of biosynthetic intermediates may contribute, by mechanisms as yet unknown, to the regulation of synthesis of enzymes involved in bacteriochlorophyll formation.
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The Formation of Ribulose 1:5-Diphosphate Carboxylase by Growing Cultures of Athiorhodaceae
More LessSummary: Ribulose l:5-diphosphate carboxylase, which catalyses the conversion of ribulose l:5-diphosphate and CO2 to 3-phosphoglyceric acid, is a key enzyme in the reductive pentose cycle. It was formed only in traces by Rhodopseudomonas spheroides growing in the dark under conditions of high or low aeration but organisms grown photosynthetically were rich in the enzyme. The activity of some other enzymes of the cycle, phosphoriboisomerase, phosphoglyceric acid kinase and triosephosphate dehydrogenase (diphosphopyridine nucleotide-linked) did not vary significantly with the growth conditions. The differential rate of synthesis (increase in enzyme/ increase in culture density) of the carboxylase was studied in cultures of R. spheroides growing exponentially under various conditions. It was influenced by the light intensity, being decreased when this was increased. Oxygen completely repressed formation of the enzyme even under continuous illumination; this effect was annulled by restoration of anaerobic conditions. Dark-grown organisms formed the enzyme at a high differential rate immediately on transfer to anaerobic + light conditions, provided that they contained a minimal amount of bacteriochlorophyll. Biotin deficiency did not affect the synthesis of the carboxylase. The conditions which promoted carboxylase formation were in many respects similar to those favourable to synthesis of enzymes required for the early stages of bacteriochlorophyll formation. The connexion of these observations with the regulation of pigment synthesis and with the possible physiological role of the enzyme in the Athiorhodaceae is discussed.
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The Formation of Isocitratase by the Athiorhodaceae
More LessSummary: Isocitratase, which cleaves isocitrate to glyoxylate and succinate and is a key enzyme in the glyoxylate cycle, is formed by Rhodopseudomonas palustris and R. capsulatus when grown on acetate or butyrate either anaerobically in light or aerobically in the dark. Only traces of the enzyme are present in organisms grown on succinate or malate. In contrast, isocitratase is detectable in traces only in R. spheroides and Rhodospirillum rubrum grown on acetate, butyrate or other substrates. This suggests that the glyoxylate cycle cannot account for net synthesis of cell constituents from acetate or acetate precursors in these latter two organisms.
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The Effect of Inhibitors on the Formation of Flagella by Salmonella typhimurium
More LessSUMMARY: The synthesis of flagella by Salmonella typhimurium was used in a study of factors affecting the formation of a single protein. Regeneration of flagella by mechanically deflagellated organisms was completely inhibited by 2 : 4-dinitrophenol (0·001 m), but not by sodium azide (0·004 m), or by sodium arsenate (0·002 m). Ultraviolet (u.v.) irradiation or treatment with nitrogen mustard in a dose sufficient to result in a 99·99 % decrease in viable count, completely inhibited regeneration of flagella. None of the amino acid, purine or pyrimidine analogues tested, with the exception of p-fluorophenylalanine, prevented the regeneration of functional flagella, although many of them inhibited bacterial growth. Flagella synthesized in the presence of p-fluorophenylalanine were non-functional and the flagella wavelength was half that of the control. Growth of S. typhimurium at 44° resulted in a progressive decrease in the number of flagella/bacterium. On continued incubation at 44° the culture became non-motile. Subsequent incubation at 37° resulted in the recovery of motility after a lag about equal to the mean generation time of the bacteria. Addition of 2-thiouracil or 8-azaguanine to a non-motile culture immediately after transferring from 44° to 37° prevented the recovery of motility. When the addition of 8-azaguanine was delayed for 1 hr. after transferring from 44° to 37°, there was no inhibition of recovery of motility. The growth of S. typhimurium at 37° was not completely inhibited by 2-thiouracil (0·001 m) or 8-azaguanine (0·001 m), but there was a fall in no. flagella/bacterium after the addition of the analogue. Since regeneration of flagella occurred at 44°, these data were interpreted as indicating that the systems responsible for the formation of flagella were absent from cultures grown at 44°, but were synthesized during the lag before the appearance of flagella on transferring the culture to 37°.
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Interrelationship between Colicin Sensitivity and Phage Resistance
More LessSUMMARY: When cultures of Escherichia coli strain 15 were irradiated with ultraviolet radiation, the bacteria were induced to form a bactericidal material, colicin-15. Colicin-15 was released by the lysis of bacteria which underwent a residual growth without division. The only strains of bacteria sensitive to the action of colicin-15 were derivatives of strain 15. Three colicin-resistant strains were obtained, all of which became simultaneously sensitive to every T-phage, while the colicin-sensitive parental strains were lysed only by T2. By stepwise reversal of the phage sensitivity pattern, it was possible to revert colicin-resistant mutants to colicin sensitivity again. Only certain mutations conferring resistance in concert to phages T1, T3, T4, T5 and T7 seemed to result in colicin sensitivity. A model which will account for these phenomena is presented.
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The Fine Structure of Bacteriophages
D. E. Bradley and D. KaySUMMARY: The ‘negative contrast’ method for the preparation of viruses for electron microscopy was used to study 22 different bacteriophages. A great variety of features is described, leading to some morphological grouping. The use of uranyl acetate on coli phage T 5 revealed subunit structure in both the head and tail, features not shown by the conventional phosphotungstic acid treatment.
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An Improved Method for Viable Counts of Bacteria of the Ovine Rumen which ferment Carbohydrates
More LessSUMMARY: A method is described which is suitable for routine viable counts of rumen bacteria capable of fermenting various carbohydrates. The contribution of different steps in the preparation of the medium towards the final redox potential was determined and the choice of a suitable reducing agent, redox indicator and source of rumen fluid supplement is discussed. In a sheep on a constant practical ration, the variation in numbers of cellulolytic bacteria was greater than the differences between five successive samples withdrawn at one time, and much greater than the variation due to the method.
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The Lysogenicity of Staphylococci isolated in Poland
More LessSUMMARY: Strains of staphylococci were tested for lysogenicity and different ‘lysogenicity patterns’ were defined on the basis of the phage lytic spectra. The test of lysogenicity was used to indicate the pathogenicity, and to complement the phagetyping pattern. None of the coagulase-negative strains (65) carried a phage. The lysogenicity patterns of 76% of the coagulase-positive strains (122 tested) were determined. With the method of phage typing 80 % of the coagulase-positive strains of staphylococci were classified. By using both methods (phage-typing and the test of lysogenicity) the classification of 92 % of coagulase-positive strains was possible. Differentiation of identical phage-typing patterns was obtained by using lysogenicity patterns.
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A New Type of Flagellar Variation associated with New Antigens in the Salmonella Group
More LessSUMMARY: A new type of phase variation which changes in one direction only has been noted in some members of the Salmonella group. This was found in association with three hitherto undescribed flagellar antigens, z43, z45 and z46, which are characterized. These occurred naturally with particular frequency in Salmonella group E and in cultures which possessed an alternate g, s, t phase. Two of these antigens, z43 and z45, were found less frequently in other O groups and in organisms possessing other alternative phases. Although the antigens in question can be readily transformed to the alternate phases of the organisms in which they occur, these alternate phases could not be changed to z43, z45 or z46.
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The Properties of some Antigens of Trypanosoma brucei
More LessSUMMARY: A soluble trypanosomal antigen occurs in the serum of rats infected with Trypanosoma brucei. This ‘exoantigen’ is probably not a protein and is electrophoretic- ally a slow-moving component in the serum. The exoantigen which is also present on the surface as an agglutinogen appears to protect the trypanosomes against adverse environment, preserving their infectivity for long periods in vitro. Rats and mice immunized with exoantigen are protected against infection with the homologous strain of T. brucei. Rabbits infected chronically with T. brucei form antibodies to exoantigen. On disintegration of the trypanosomes, in addition to exoantigen, ‘bound’ antigens are released. In the natural disease exoantigens induce antibodies which may be concerned with protection against further infection.
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A Classification of the Klebsiella Group
More LessSUMMARY: Klebsiella strains are divided into six categories on the following reactions: fimbriation, production of gas from glucose at 37°, acid from lactose and dulcitol, methyl red test, acetoin production, citrate, urease, gluconate, malonate, lysine decarboxylase, growth in the presence of KCN and ability to produce gas from lactose at 44°. Five of the six categories are assigned specific rank, the sixth subspecific rank. The tests enable Friedländer’s pneumobacillus to be distinguished from Aerobacter aerogenes. A new species, Klebsiella edwardsii, and a new subspecies, K. edwardsii var. atlantae, are named. Neotype strains of old species are proposed, holotypes of the new species and variety designated, and the catalogue numbers in the National Collection of Type Cultures and American Type Culture Collection given.
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The Titration of Trachoma and Inclusion Blennorrhoea Viruses in Cell Cultures
More LessSUMMARY A technique is described for titrating trachoma and inclusion blennorrhoea viruses by counting the inclusions formed in HeLa cell monolayers. The method compares favourably in accuracy with other techniques used for the assay of viruses and is more reliable than titration in the chick embryo yolk sac.
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Serological Typing of Strains of Streptococcus faecium and Unclassified Group D Streptococci Isolated from Canned Hams and Pig Intestines
More LessSUMMARY A collection of 85 strains of Streptococcus faecium and unclassified group D streptococci isolated from canned hams and pig intestines was typed serologically. Seventy-seven of the isolates, which included two motile strains, were distributed amongst 15 types and 4 subtypes. The distribution of types was widespread, the same type being isolated from several different countries.
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