- Volume 19, Issue 3, 1958
Volume 19, Issue 3, 1958
- Article
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On the Intestinal Yeast Flora of Horses, Sheep, Goats and Swine
More LessSUMMARY: From the caeca of 252 horses, 503 sheep, 250 goats and 250 swine, 486 yeast isolates belonging to 28 species and 1 variety were obtained. The distribution of the yeasts of any species and for Candida albicans respectively was: horses, 52·4%, 4·4%; sheep, 6·8%, 4·2%; goats, 6·4%, 08%; swine, 88·8%, 9·2%. The suitability of the sheep and goats as hosts for yeasts of any species seems very limited.
The most frequent occurrences for single species were: Candida slooffii in swine (48·4%), Trichosporon cutaneum in horses (21·8%) and Saccharomyces tellustris (Candida bovina) in swine (14%).
One isolate of Cryptococcus neoformans was obtained from a healthy horse, suggesting that horses might sometimes contribute to the dispersal of this pathogen. Temperature relations, vitamin requirements and some assimilative properties of the following organisms were determined (total number of isolates in brackets): Saccharomyces tellustris (3), Torulopsis glabrata (6), T. pintolopesii (10), Candida bovina (6), C. slooffii (6), Cryptococcus neoformans (23) and Trichosporon cutaneum (12).
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The Morpholoǵy of Leptotrichia Species
More LessSUMMARY: The morphology is described of two species of filamentous oral bacteria, both of which have in the past been accorded the same name, Leptotrichia buecalis. Although these have certain characters in common, it is concluded that they are entirely distinct. Both show signs of a residual life-cycle, suggesting a remote relationship with more complex saprophytes.
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The Purification and Concentration of Viruses and Virus Soluble Antigens on Calcium Phosphate
More LessSUMMARY: Chromatography on columns of calcium phosphate has been used to purify and concentrate viruses and their related soluble antigens. The method is an adaptation of one which has already proved successful with proteins and other large molecules. An important advantage is that all operations are carried out at pH 7, elution being effected by alterations in phosphate concentration. The PR 8 strain of influenza was used as a model. Chromatrography on a calcium phosphate column effected a 30- to 100-fold increase in purity, with a recovery of 50–80 %. By chromatography on a second small column a 10- to 30-fold concentration could be obtained; little further purification occurred. Material with a purity up to 106 haemaggluti-nation units/mg. protein was obtained; this compares favourably with material purified by other methods. PR 8 soluble antigen was similarly purified and concentrated, and Semliki forest virus was also purified. In preliminary experiments, purification of vaccinia, encephalomyocarditis, Coxsackie and poliomyelitis type III viruses has also been effected. The method is simple and rapid and can be used with crude virus suspensions from different sources. The viruses retained both their infectivity and their antigenicity as judged by complement fixation.
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Some Studies on the Occurrence and Properties of a Larǵe Gram-Neǵative Coccus from the Rumen
More LessSUMMARY: A large Gram-negative coccus was isolated in a lactate-containing medium from the rumen of young calves. This organism is anaerobic and ferments only lactate, glucose, fructose, maltose, sucrose, mannitol and sorbitol. The coccus is found in large numbers (c. 109/ml.) in the rumen contents of young calves, but is present only in small numbers or is absent from the rumens of older cattle and sheep. An attempt made to establish the organism in large numbers in a sheep rumen was unsuccessful. The possibility of the coccus being a normal inhabitant of the throat of adult animals was also examined. Five serological types were obtained. The distribution of these types in the same animal over a period, and in different animals, appears to be random. The distribution of a small lactate-fermenting coccus (Veillonella gazogenes) is also described.
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The Effect of Infectinǵ the Cells of the De-embryonated Egg with Influenza Virus on their Uptake of Glucose and Amino Acids
More LessSUMMARY: A method was found for infecting all the cells of the de-embryonated hen’s egg with influenza B virus (strain Lee). Infected cells took up more glucose from the culture medium than did uninfected cells. Neither infected nor uninfected cells took up any of six amino acids, given singly. A mixture of thirteen amino acids was taken up well, and to the same extent, by infected and uninfected cells. When cysteine, histidine or methionine was omitted from this mixture, the remaining amino acids were taken up better by uninfected cells than by infected cells; when any other amino acid (arginine, glutamine, isoleucine, leucine, lysine, phenylalanine, threonine, tryptophan, tyrosine, valine) was omitted there was no significant difference in uptake by infected and uninfected cells. In this system, ethionine delayed multiplication of influenza virus, but β-phenylserine did not. These results are consistent with an increased requirement of the infected cell in this system for cysteine, histidine and methionine.
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Studies on the Bacterial Component of Soybean Root Nodules: Cytoloǵy and Organization in the Host Tissue
More LessSUMMARY: Light- and electron-microscope studies of bacteroids in soybean nodule sections and suspensions of isolated bacteroids have shown well-defined nuclear elements, containing tangled filaments and dense granules. The cytoplasm was poorly stained as seen in the light microscope but had considerable dye-reducing activity localized at the poles, giving the appearance of granules. However, electron micrographs revealed no electron dense granules in the cytoplasm near the poles. Cell walls were not found on bacteroids in suspensions isolated from nodules, but were present on bacteria grown in vitro, and on bacteroids in the host tissue. Electron micrographs of thin sections of mature nitrogen-fixing nodules revealed a system of double membranes enclosing groups of four or six bacteroids. These membranes appeared to originate from the host cells and their development was followed in nodules aged from 1–5 weeks; they could be centrifugally separated from the bacteroid fraction of crushed nodules. The origin of the membrane system and its possible role in nodule functions is discussed.
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The Globular Involution Forms of the Bifid Bacteria
More LessSUMMARY: The globular swellings known to appear occasionally in cultures of the bifid bacteria have been shown to occur in all known types of Lactobacillus bifidus. The swellings developed on a substrate which permitted abundant growth. The development of the globular involution forms was prevented by the addition of tryptic digest of cow’s milk to the substrate. The similarity between the globular forms of L. bifidus and protoplasts is mentioned. The globular forms are considered to be organisms with incomplete cell walls which develop on a substrate adequate for growth but not for normal cell wall synthesis.
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The Effect of Actidione and other Antifunǵal Aǵents on Nucleic Acid and Protein Synthesis in Saccharomyces carlsbergensis
More LessSUMMARY: The antifungal compound actidione has been found to inhibit both nucleic acid and protein synthesis in Saccharomyces carlsbergensis. At the minimum growth inhibitory concentration synthesis of deoxyribonucleic acid and protein is completely inhibited, whereas the synthesis of ribonucleic acid continues for some time after the addition of the antibiotic to the culture. Some other antifungal agents were found to inhibit both nucleic acid and protein synthesis, but in no case was any differential effect obtained.
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The Differential Effect of Temperature on Gas Production by a Coliform Orǵanism
More LessSUMMARY: The influence of the temperature of incubation on the course of formic acid and gas production by cultures of a coliform organism growing in buffered and unbuffered peptone media was studied. The evidence suggests that at 30° and at 37° the onset of gas production is determined by the concentration of undissociated formic acid in the culture, but that a higher concentration of acid is required to elicit response at 37° than at 30°. Undissociated formic acid is toxic to the organism and it appears that gas is not produced in unbuffered glucose medium at 37° because the environmental conditions do not allow elaboration of hydrogenlyase before inhibitory conditions of pH value and formate concentration are attained.
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The Sensitivity of Vibrio fetus to Streptomycin and the Emerǵence of Resistant Mutants
More LessSUMMARY: Forty-five strains of Vibrio fetus were examined for streptomycin sensitivity; in most cases, growth was inhibited by concentrations ranging from 0·5–20 μg./ml. Streptomycin resistance was found in 6 strains. By the replica plating technique it was shown, in the case of 1 strain, that resistance was due to spontaneous mutation which occurred in the absence of streptomycin.
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Studies of Extracellular and Intracellular Bacterial Deoxyribonucleic Acids
More LessSummary: Highly polymerized bacterial deoxyribonucleic acids (DNAs) obtained from extracellular and from intracellular locations were analysed. DNAs from two strains (Staphylococcus aureus and S. epidermidis) were of the type having high adenine and thymine contents; two others (Alcaligenes faecalis and Pseudomonas Jluorescens) had a high content of guanine and cytosine. For each micro-organism the composition of extracellular DNA was essentially the same as that of the intracellular DNA. Conditions associated with the extracellular accumulation of DNA in cultures of 3 strains were investigated. S. aureus elaborated a deoxyribonuclease (DNase) which required calcium ion and high pH for activity. In a culture medium of c. pH 6 and insufficient calcium, the DNase was inactive and DNA slime accumulated. In cultures of P. fluorescens a specific ribonuclease-sensitive DNase inhibitor protected slime DNA from depolymerization by culture DNase. In cultures of A. faecalis, also, both a DNA slime and a low concentration of DNase may occur. This enzyme, detected by studying its action against solutions of calf thymus DNA prepared from dried fibres, was activated by various cations within the pH range of cultures. Unlike other DNases, however, it has little capacity to attack the slime-layer DNA, which presumably is more nearly native.
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The Influence of pH on the Antibacterial Action of Subtilin A
More LessSummary: The influence of pH value on the antibacterial action of subtilin A has been demonstrated by survivor counts, inhibition of respiration, and pH gradient plates. Staphylococcus aureus is more sensitive to subtilin as the pH value increases; Escherichia coli is more sensitive as the pH value decreases. The results are analogous to those obtained by other investigators working with cationic detergents, and are consistent with the hypothesis that the basic surface-active antibiotics kill bacteria by the same general mechanism as do the quaternary ammonium germicides. A survey of the growth inhibition of other organisms on pH gradient plates indicates that Bacillus cereus behaves like S. aureus, while B. megaterium, Corynebacterium poin- settiae, and Streptococcus faecalis behave like E. coli.
A pH/mobility curve for subtilin A, obtained by paper electrophoretic studies, indicates no striking changes in the charge of the molecule over the pH range 4–9, although the presence of at least one free α-amino group is indicated by inflexion points in the range of pH 6–7. The isoelectric point of subtilin A at ionic strength 0·1 is approximately 6·7.
The use of sectored, square-shaped Petri dishes for pH-gradient plate studies with germicides is described.
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An Electro-Taxonomic Survey of Bacteria
More LessSummary: A taxonomic survey of a wide range of bacteria has been made with the aid of an electrical computing machine. The strains examined fell into five main groups: (1) Gram-positive organisms, including streptococci, micrococci, staphylococci, Aerococcus, Erysipelothrix, Listeria and certain diphtheroids; (2) predominantly Gram-negative organisms, including enterobacteria, pseudomonads Pasteurella, Vibrio, Actinobacillus, Loefflerella, Brucella, Neisseria, Chromobacterium and also Bacillus', (3) Corynebacterium diphtheriae; (4) acid-fast bacilli; (5) spirilla.
Within group 1 were subgroups representing Streptococcus, Micrococcus and Staphylococcus. Within group 2 were subgroups representing: (a) most enterobacteria together with Pasteurella pestis and Vibrio; (b) Brucella, Neisseria, Actinobacillus lignieresi, Pasteurella septica and possibly also Shigella; (c) pseudomonads; (d) Bacillus; (e) Chromobacterium violaceum and (f) Proteus.
The taxonomy suggested by this study is compared with that in current use. Temporary working type strains of most of the species are suggested for use in surveys of this kind. The limitations of the method and of using old laboratory records are discussed.
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On the Infrared Absorption Spectrum of Bacillus megaterium
More LessSummary: The infrared absorption spectra of the aerobic spore-forming bacilli are variable. Evidence is presented to show that, for Bacillus megaterium, the nature of the spectrum is related to the morphology of the bacteria, both showing a cyclic variation with time. The time scale of the cycle is affected by the temperature at which the cultures are incubated, by their population density and by the medium on which they are grown; it may be affected by induced drug resistance. Some of the characteristics of the spectrum of vacuolated vegetative organisms are due to the presence of an extractable substance which may be a polymer of β -hydroxybutyric acid. Difference spectroscopy is used to demonstrate the presence of this substance, its disappearance as the bacteria autolyse and the appearance of β-hydroxybutyric acid in the autolysed material. This technique is applied also to establish the state of dipicolinic acid in the resting spores of B. megaterium. Any application of infrared spectroscopy to the study of aerobic spore-forming bacilli must take account of the morphological state of the bacteria.
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Torulopsis ingeniosa n.sp., from Grass Leaves
More LessSummary: An undescribed species of Torulopsis has been isolated from pasture grass leaves. It does not ferment sugars and assimilates glucose, sucrose, maltose, lactose, galactose and potassium nitrate. It is distinguished from Torulopsis aeria by the oval shape of its cells, mucoid cultures on solid media, and the ability to liquefy gelatin rapidly. It is proposed to name it T. ingeniosa.
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Dihydrostreptomycin and Anaerobiosis—Indirect Evidence for Two Sites of Action of Dihydrostreptomycin
More LessSummary: The sensitivity of 4 strains of Escherichia coli and of Aerobacter aero-genes when growing under aerobic and under anaerobic conditions in heavily buffered enriched medium was compared. Each comparison covered a series of pH values from 5·5 to 8·0. A distinct pattern emerged for each group of organisms and this would appear to be related to the enzymic make-up of the organism with respect to carbohydrate metabolism and not to the pH developed in the medium during growth or to the growth rate of the organism. Comparison of the behaviour of A. aerogenes under identical conditions, but in a simple medium, suggests that dihydrostreptomycin is more effective against synthesizing than against energy-producing mechanisms.
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Dependency on Medium and Temperature of Cell Size and Chemical Composition during Balanced Growth of Salmonella typhimurium
More LessSummary: Ceil mass, the average number of nuclei/cell and the content of RNA and DNA were studied in (Salmonella typhimurium during balanced (steady state) growth in different media. These quantities could be described as exponential functions of the growth rates afforded by the various media at a given temperature. The size and chemical composition characteristic of a given medium were not influenced by the temperature of cultivation. Thus, under conditions of balanced growth, this organism exists in one of a large number of possible stable physiological states.
The variations in mass/cell are due to changes in the number of nuclei/cell as well as in mass/nucleus. An increase in the number of ribonucleoprotein particles at higher growth rates could, it appears, largely account for the increase in mass/nucleus. Calculations indicate that the rate of protein synthesis per unit RNA is nearly the same at all growth rates.
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The Transition Between Different Physiological States During Balanced Growth of Salmonella typhimurium
More LessSummary: When cultures of Salmonella typhimurium undergoing balanced growth are shifted from one medium to another, a definite pattern of rate changes is observed. Shifts from a low to a high growth rate result in a strict succession of events: RNA synthesis is immediately affected and its rate rapidly increases to that characteristic of the new medium; the increase in optical density shows a lag of a few minutes before the new rate is attained; DNA synthesis and cell division, on the other hand, continue at the old rate for appreciable periods of time and then abruptly shift to the new rates. The times at which these shifts take place are, at 37°, invariably 20 and 70 min., regardless of the actual growth rates before and after the shift. This rate maintenance effect on DNA synthesis and cell division is discussed in terms of specific rate-controlling mechanisms.
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The Nutritional Requirements of Rumen Strains of Streptococcus bovis Considered in Relation to Dextran Synthesis from Sucrose
More LessSummary: Five rumen strains of Streptococcus bowis all required biotin for good anaerobic production of dextran from sucrose in a simple acetate+bicarbonate + amino acids medium. Three of these strains required at least pantothenate also. When phosphate replaced acetate as a buffer, dextran production did not occur unless a soluble protein was also supplied in the medium.
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