-
Volume 28,
Issue 1,
1962
Volume 28, Issue 1, 1962
- Article
-
-
-
Fimbriae and Haemagglutinating Activity in Strains of Proteus hauseri
More LessSUMMARY: Fimbriae were seen with the electron microscope on each of 79 strains of Proteus hauseri when these were in the haemagglutinating phase, but were absent from the non-haemagglutinating phase. All strains were variably fimbriate. The fimbriate mutant became dominant under anaerobic or relatively anaerobic cultural conditions. The non-fimbriate mutant became dominant under aerobic conditions. The properties of Proteus fimbriae are compared with those of Escherichia coli and Shigella flexneri. The fimbriation change is correlated with other mutations in Proteus strains.
-
-
-
-
Aberrant Forms of Mycobacterium phlei Produced by Streptomycin and their Multiplication on Streptomycin-free Media
More LessSUMMARY: Aberrant forms in a streptomycin-sensitive strain of Mycobacterium phlei could regularly be shown to arise in the presence of low concentrations of streptomycin. The effect of streptomycin on the morphology of M. phlei is comparable with that of penicillin on the morphology of organisms belonging to the Enterobacteriaceae. The transfer of aberrant forms of M. phlei to a streptomycin-free medium resulted in the atypical multiplication of these forms.
-
-
-
Rate of Growth of Bacillus cereus Between Divisions
More LessSUMMARY: Bacillus cereus organisms growing exponentially have a stable length distribution. This length distribution can be analysed by the method described to give the mean rate of increase in length of organisms at any given length. The validity of the method was confirmed by observing the growth of clones of B. cereus in the culture chamber. Both methods showed that the rate of increase in length increased as the organisms got longer, and that there was no hesitation before or after division. Possible applications of this general method to other parameters that can be measured in samples of bacteria taken from stable populations are suggested.
-
-
-
Chemical Composition and Antigenic Structure of Cell Walls of Corynebacterium, Mycobacterium, Nocardia, Actinomyces and Arthrobacter
More LessSUMMARY: A comparison has been made between the chemical composition of the cell walls of strains from the genera Corynebacterium, Mycobacterium, Nocardia, Actinomyces and Arthrobacter, and the antigenic composition of the same cell-wall fractions as judged by an agglutination test. A common antigenic component was identified in all those strains of corynebacteria, mycobacteria and nocardias which have arabinose and galactose as their principal cell-wall sugars. Some strains of corynebacteria, and 3 strains of Nocardia pelletieri which have a different pattern of cell-wall components, appear to lack this cell-wall antigen. The antigen was not present in the cell walls of 8 strains of actinomyces and 6 of arthrobacter. Seven of the 8 strains of actinomyces had a cell-wall composition identical with that previously described for Actinomyces israelii, and these 7 strains formed a homogeneous group serologically: the other actinomyces strain differed in cell-wall wall composition and its cell walls did not agglutinate with the ‘israelii’ serum, nor did those of any of the 6 strains of arthrobacter, although some of the latter resemble A. israelii in cell-wall structure. These results show that the antigenic studies tended to confirm relationships suggested by cell-wall composition alone, especially among corynebacteria, nocardias and mycobacteria: they also suggest that Corynebacterium as at present constituted is a mixture of species of diverse origin.
-
-
-
Electron Microscope Observations on the Structure of Fimbriae, with Particular Reference to Klebsiella Strains, by the use of the Negative Staining Technique
More LessSUMMARY: The method of application of negative staining with potassium phosphotungstate for the electron microscopy of bacterial surface structure is described. The method has been used to study the fimbriae of Klebsiella strains, and has confirmed, qualitatively, the results of other workers who used the shadow-casting technique. The diameters of the two types of fimbriae associated with the MS and MR adhesins were found to be 65-70 Å and about 48 Å, respectively. These figures are about 30 % less than earlier estimates. The resistance of both types of fimbriae to prolonged autolysis was shown. Other applications of the negative staining method include the study of bacterial flagellation, and of the structure of cells disintegrated by autolysis or other methods.
-
-
-
Sulphydryl Metabolism of Fungi Grown in Submerged Culture
More LessSUMMARY: Radioactive phenyl mercuric chloride (labelled with 203Hg) was used to measure-SH groups in the mycelium and in the medium. Tritiated phenyl mercuric chloride was used as a quantitative cytological reagent. The changes in -SH concentration of the fungus were not always directly related to the changes in total S in Aspergillus niger, Penicillium chrysogenum 49.133, Eremothecium ashbyii and Candida albicans. A peak in -SH concentration occurred in the cells of these organisms during the early growth phase. Extracellular -SH compounds were produced by all these organisms at some time during development. Cytological studies showed differences in the distribution of -SH compounds in the cell wall and cytoplasm. E. ashbyii and C. albicans had a strong -SH reaction in the cell wall, A. niger and P. chrysogenum 49.133 a weak one. Sulphydryl compounds were most concentrated in areas of hyphal bud formation in E. ashbyii but were not concentrated at the hyphal tip.
-
-
-
The Infrared Spectra of Some Acetic Acid Bacteria
More LessSUMMARY: The infrared spectra of 22 strains of the genus Acetobacter were significantly different from those of 9 strains of the genus Acetomonas, with one exception. Within each genus, however, the spectra formed smooth graduated series which showed no sudden differences which could be correlated with species boundaries, and exhibited no features which could be traced to the presence or absence of particular biochemical properties. These results support the division of the acetic acid bacteria into two genera Acetobacter and Acetomonas and render unlikely the existence of distinct species within the genera.
-
-
-
The Formation and Germination of Microcysts in Myxococcus xanthus
M. Dworkin and H. VoelzSUMMARY: An investigation has been made of the sequence of morphological events involved in the processes of microcyst formation and germination in the fruiting myxobacterium Myxococcus xanthus. By using time-lapse photo-micrographs and phase-contrast microscopy of living cells, microcyst formation is shown to involve a shortening and thickening of the entire vegetative cell with a subsequent increase of refractility. Germination is preceded by the casting off of a sheath followed by the gradual elongation and loss of refractility of the cell. Vegetative rods will readily form spheroplasts when exposed to a variety of conditions including sulphydryl compounds. The necessity for distinguishing between spheroplasts and microcysts is pointed out.
-
-
-
The Pathogenicity of Bacillus anthracis Lysogenic with Mutants of Phage W
More LessSUMMARY: Mutants of phage W with diverse virulence were used to lysogenize naturally occurring strains of Bacillus anthracis and their non-capsulogenic derivates. The temperate mutant β readily established itself as a prophage in both sporogenous and non-sporogenous strains of B. anthracis. Strains carrying β-prophage were stable, capable of giving rise to colonies, and their multiplication was not impaired in the mouse. Thus, the virulence of capsulogenic strains, lysogenic for phage β, was not diminished. A less temperate mutant of phage W, phage α, was not capable of lysogenizing an atypical asporogenous strain of B. anthracis, but formed more or less stable complexes with sporogenous strains. The stability of spores carrying phage genome α covered a wide range. Most of such spores did not give rise to colonies after germination but instead formed plaques. In some spores, however, phage α established itself as prophage so that stable lysogenic bacteria could be obtained under certain conditions. Spores of both capsulogenic and non-capsulogenic strains of B. anthracis lysogenic for phage α formed the same number of either plaques or colonies when plated on a sensitive indicator strain or spread on agar surface. When, however, the spores were spread on agar containing 0.025 M-sodium bicarbonate and the plates incubated at a high partial pressure of CO2, then phage development in the lysogenic spores was induced. Hence, under these conditions, the lysogenic spores did not give rise to colonies but lysed and liberated phage. A small proportion of capsulogenic spores carrying prophage α threw off non-lysogenic segregants which gave rise to mucoid colonies in CO2. These mucoid colonies consisted of encapsulated bacteria which probably remained non-lysogenic because their capsules prevented re-infection during their growth. Capsulogenic strains carrying prophage α were markedly less virulent in the mouse and this may be explained by induction of α-prophage by high CO2 tension in the animal body.
This competition between prophage induction and capsule formation, both of which were induced by high CO2 tension, explains the apparent diminution of the virulence of strains of B. anthracis lysogenic for α-phage.
-
-
-
Characters of a Group of Bacillus Phages
More LessSUMMARY: The general characters are given of a group of phages related to phage β, a temperate phage carried by Bacillus cereus strain W (McCloy, 1951, 1953, 1958). One phage, β´, has been isolated only once but may be a mutant of phage β since it, and its clear plaque variant, γ´, have many properties in common with the other phages.
-
-
-
Enumeration of Rumen Micro-organisms
More LessSUMMARY: Techniques are described for counting and differentiating the rumen microbial population. The rumen liquor is fixed and preserved in formol saline, and counts are made in two counting chambers, whose dimensions depend on the size of the organism to be counted; stained smears of the bacteria are also examined. Counts made on small samples of rumen liquor obtained through a fistula have been compared with counts on samples of the entire rumen contents; the ratio of these counts seemed to depend on the particular organism counted, the ration and the time after feeding. The importance of differential as opposed to total counts is emphasized.
-
-
-
Some Factors Influencing the Rumen Microbial Population
More LessSUMMARY: In sheep fed once daily, the concentrations of micro-organisms in the rumen changed with the time after feeding, some organisms fluctuating in numbers more than others; peak concentrations were reached at different times for different organisms. These changes in concentration were reflected in changes in the proportion of dividing cells, for example, in Dasytricha ruminantium this proportion varied from less than 0.2% throughout most of the day to a maximum of 23 % a few hours before feeding; for Entodinium spp. the variation was less: it was possible to calculate the minimum doubling time for these latter organisms as about 5 hr.
One animal at different times, or different animals, on the same ration and dietary regime had very different rumen microbial populations, these differences being particularly marked in the case of some organisms. Reasons why these marked differences in microbial population are not reflected in similarly marked differences in over-all rumen metabolism are discussed.
Feeding different quantities of the same ration had little effect on the concentration of rumen microbes, provided the ration was above a minimal level; it is, however, suggested that output of microbial cells from the rumen may have varied with the amount of feed given. Starvation for a few days or prolonged under-nutrition had a marked effect, some organisms being drastically reduced in numbers or dying out completely. When the qualitative nature of the diet was changed, about 10 days were needed to complete the major adjustments in the rumen microbial population.
-
-
-
Effect of Biotin-Sparing Substances on Growth of Biotin-Deficient Saccharomyces cerevisiae and on the Synthesis of Nucleic Acids and Protein
More LessSUMMARY: An examination was made of the ability of amino acids, purines and related compounds, and fatty acids to stimulate growth of Saccharomyces cerevisiae in biotin-deficient medium and to restore the synthesis of nucleic acids and protein. Adenine, adenosine, aspartic acid and Casamino acids (Difco) each stimulated growth to some extent and brought about a partial restoration of nucleic acid and protein synthesis. Oleic acid also stimulated growth, but the effect was much slower than that brought about by the other biotin-sparing compounds tested and it was not accompanied by a restoration of nucleic acid and protein synthesis. Stimulation of growth in biotin-deficient media supplemented with aspartic acid + oleic acid was greater than the stimulation brought about by these compounds singly. During growth of the yeast in biotin-deficient media supplemented with this or certain other mixtures of biotin-sparing compounds there was a well defined exponential phase of growth which was not apparent during growth of the yeast in unsupplemented biotin-deficient medium. But the final cell crop in these supplemented media was still only about half of that obtained in biotin-optimal medium. These results are discussed in relation to the role of biotin in the synthesis of various yeast cell constituents.
-
-
-
Evidence for a Flavoprotein Photoreceptor in Phycomyces
More LessSUMMARY: It is shown that the flavin inhibitors mepacrine and lumichrome have a greater effect on the growth of illuminated than unilluminated static liquid cultures of Phycomyces. The possible relevance of these findings to our understanding of the mechanism of phototropism is discussed.
-
-
-
Salmonella enteriditis as a Genetic Donor in Intraspecific and Interspecific Grosses Initiated by Colicine Factors
More LessSUMMARY: Colicine factors I and E1 enable Salmonella enteriditis, like S. typhimurium, to pair at high frequency (e.g. with 50-90 % of recipient cells) either with its own derivatives or with those of other species such as S. typhi and S. typhimurium. However, genetic recombinants occur at only low frequency in intraspecific crosses (about 10−7 of recipient cells); whereas in interspecific crosses with S. enteriditis as donor, recombination with S. typhimurium involving either closely linked or single markers occurred at an even lower frequency (about 10−9 of recipient cells). No detectable recombinants were isolated when using either S. enteriditis or S. typhimurium as donor and S. typhi as recipient, although colicine factors were transferred at high frequency.
-
-
-
Absence of the Group-specific and the Cell-wall Polysaccharide Antigen in L-phase Variants of Group D Streptococci
More LessSUMMARY: The L-phase variants of group D streptococci, analysed in this study, were not only characterized by the absence of the cell-wall polysaccharide antigen, but also by the absence of the group D antigen, which is not a constituent of the cell wall.
-
-
-
Indifferent and Haemolytic Streptococci Possessing Group-Antigen F
More LessSUMMARY: ‘Indifferent’ strains of streptococci-i.e. strains which give no haemolysis or greening on blood-agar plates-frequently occur in cultures from dental root-canals. A serological study of over 200 strains of these streptococci showed that about half of them belonged to Lancefield groups F, G or C. It was shown by cross-absorption that the group-antigen of indifferent streptococci of group F is identical with the group-antigen of haemolytic strains of group F. Apart from the group-antigen, five independent carbohydrate type-antigens, localized in the cell wall, were demonstrated in group F strains. These type-antigens were found in groups other than F, e.g. the type-antigen I was observed in haemolytic and indifferent strains of group G; the type-antigen III occurred in indifferent strains of group C. Several strains with a type-antigen but without group-antigens were observed. The presence of carbohydrate type-antigens in formamide extracts can cause confusing cross-reactions in the grouping procedure, unless strains without type-antigen are used for the preparation of sera.
-
Volumes and issues
-
Volume 169 (2023)
-
Volume 168 (2022)
-
Volume 167 (2021)
-
Volume 166 (2020)
-
Volume 165 (2019)
-
Volume 164 (2018)
-
Volume 163 (2017)
-
Volume 162 (2016)
-
Volume 161 (2015)
-
Volume 160 (2014)
-
Volume 159 (2013)
-
Volume 158 (2012)
-
Volume 157 (2011)
-
Volume 156 (2010)
-
Volume 155 (2009)
-
Volume 154 (2008)
-
Volume 153 (2007)
-
Volume 152 (2006)
-
Volume 151 (2005)
-
Volume 150 (2004)
-
Volume 149 (2003)
-
Volume 148 (2002)
-
Volume 147 (2001)
-
Volume 146 (2000)
-
Volume 145 (1999)
-
Volume 144 (1998)
-
Volume 143 (1997)
-
Volume 142 (1996)
-
Volume 141 (1995)
-
Volume 140 (1994)
-
Volume 139 (1993)
-
Volume 138 (1992)
-
Volume 137 (1991)
-
Volume 136 (1990)
-
Volume 135 (1989)
-
Volume 134 (1988)
-
Volume 133 (1987)
-
Volume 132 (1986)
-
Volume 131 (1985)
-
Volume 130 (1984)
-
Volume 129 (1983)
-
Volume 128 (1982)
-
Volume 127 (1981)
-
Volume 126 (1981)
-
Volume 125 (1981)
-
Volume 124 (1981)
-
Volume 123 (1981)
-
Volume 122 (1981)
-
Volume 121 (1980)
-
Volume 120 (1980)
-
Volume 119 (1980)
-
Volume 118 (1980)
-
Volume 117 (1980)
-
Volume 116 (1980)
-
Volume 115 (1979)
-
Volume 114 (1979)
-
Volume 113 (1979)
-
Volume 112 (1979)
-
Volume 111 (1979)
-
Volume 110 (1979)
-
Volume 109 (1978)
-
Volume 108 (1978)
-
Volume 107 (1978)
-
Volume 106 (1978)
-
Volume 105 (1978)
-
Volume 104 (1978)
-
Volume 103 (1977)
-
Volume 102 (1977)
-
Volume 101 (1977)
-
Volume 100 (1977)
-
Volume 99 (1977)
-
Volume 98 (1977)
-
Volume 97 (1976)
-
Volume 96 (1976)
-
Volume 95 (1976)
-
Volume 94 (1976)
-
Volume 93 (1976)
-
Volume 92 (1976)
-
Volume 91 (1975)
-
Volume 90 (1975)
-
Volume 89 (1975)
-
Volume 88 (1975)
-
Volume 87 (1975)
-
Volume 86 (1975)
-
Volume 85 (1974)
-
Volume 84 (1974)
-
Volume 83 (1974)
-
Volume 82 (1974)
-
Volume 81 (1974)
-
Volume 80 (1974)
-
Volume 79 (1973)
-
Volume 78 (1973)
-
Volume 77 (1973)
-
Volume 76 (1973)
-
Volume 75 (1973)
-
Volume 74 (1973)
-
Volume 73 (1972)
-
Volume 72 (1972)
-
Volume 71 (1972)
-
Volume 70 (1972)
-
Volume 69 (1971)
-
Volume 68 (1971)
-
Volume 67 (1971)
-
Volume 66 (1971)
-
Volume 65 (1971)
-
Volume 64 (1970)
-
Volume 63 (1970)
-
Volume 62 (1970)
-
Volume 61 (1970)
-
Volume 60 (1970)
-
Volume 59 (1969)
-
Volume 58 (1969)
-
Volume 57 (1969)
-
Volume 56 (1969)
-
Volume 55 (1969)
-
Volume 54 (1968)
-
Volume 53 (1968)
-
Volume 52 (1968)
-
Volume 51 (1968)
-
Volume 50 (1968)
-
Volume 49 (1967)
-
Volume 48 (1967)
-
Volume 47 (1967)
-
Volume 46 (1967)
-
Volume 45 (1966)
-
Volume 44 (1966)
-
Volume 43 (1966)
-
Volume 42 (1966)
-
Volume 41 (1965)
-
Volume 40 (1965)
-
Volume 39 (1965)
-
Volume 38 (1965)
-
Volume 37 (1964)
-
Volume 36 (1964)
-
Volume 35 (1964)
-
Volume 34 (1964)
-
Volume 33 (1963)
-
Volume 32 (1963)
-
Volume 31 (1963)
-
Volume 30 (1963)
-
Volume 29 (1962)
-
Volume 28 (1962)
-
Volume 27 (1962)
-
Volume 26 (1961)
-
Volume 25 (1961)
-
Volume 24 (1961)
-
Volume 23 (1960)
-
Volume 22 (1960)
-
Volume 21 (1959)
-
Volume 20 (1959)
-
Volume 19 (1958)
-
Volume 18 (1958)
-
Volume 17 (1957)
-
Volume 16 (1957)
-
Volume 15 (1956)
-
Volume 14 (1956)
-
Volume 13 (1955)
-
Volume 12 (1955)
-
Volume 11 (1954)
-
Volume 10 (1954)
-
Volume 9 (1953)
-
Volume 8 (1953)
-
Volume 7 (1952)
-
Volume 6 (1952)
-
Volume 5 (1951)
-
Volume 4 (1950)
-
Volume 3 (1949)
-
Volume 2 (1948)
-
Volume 1 (1947)
Most Read This Month
