- Volume 40, Issue 3, 1965
Volume 40, Issue 3, 1965
- Articles
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Extracellular Polysaccharide Synthesis by Members of the Genus Lactobacillus: Conditions for Formation and Accumulation
More LessSUMMARYMembers of the genus Lactobacillus were examined for their ability to synthesize extracellular polysaccharide from sucrose. Strains physiologically similar to L. pastorianus synthesized a glucan. Other strains liberated a complex polysaccharide which contained mannose and glucose. Variants of the glucan-producing strains occurred spontaneously and these lacked the capacity to synthesize glucan ; however, extracts of these bacilli contained glucansucrase and invertase. Manometric studies indicated that the latter enzyme functioned in the sucrose metabolism of these non-glucan producing variants.
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A Study of the Overall Similarity of Certain Actinomycetes Mainly of Oral Origin
More LessSUMMARYComputer techniques were applied to the study of 71 isolates of branching or diphtheroid bacteria from human and bovine sources. Features including morphological and colonial characteristics, nutritional and environmental growth requirements, fermentative abilities and end-products and cell-wall composition were used to determine the relationships between these organisms. The features were determined with aerobic or anaerobic growth conditions or both, according to the nature of the individual bacteria. Relationships between facultatively anaerobic micro-organisms were very similar whether the features were determined aerobically or anaerobically ; some apparently close relationships were shown between preferentially aerobic and preferentially anaerobic bacteria when they were compared with facultatively anaerobic micro-organisms.
The analysis separated groups of organisms corresponding to Actino-myces naeslundii, A. bovis, Nocardia salivae, Bacterionema matruchotii (Leptotrichia dentium) and Corynebacterium spp. The members of the various genera showed little affinity to each other. A. naeslundii and A. bovis were fairly closely related and some unplaced isolates, including typical A. israelii strains, showed a lesser relationship to either or both of these species. Isolates of A. odontolyticus showed high similarity to A. bovis and were included in this species despite their better aerobic growth. Several isolates of A. naeslundii grew well aerobically and produced catalase; production of this enzyme is not, by itself, sufficient to remove an organism from the genus Actinomyces.
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Lysis of Gram-Negative Bacteria by Host-Independent Ectoparasitic Bdellovibrio bacteriovorus Isolates
More LessSUMMARYMethods of isolation and nutritional requirements of Bdellovibrio bacteriovorus strains capable of growth on host-free media are described. Such strains retained their parasitic capacities for various Gram-negative bacteria after many transfers in host-free media. In parasite +host suspensions the spectrum of host specificity of various bdellovibrio strains was considerably wider than that obtained by examination for plaques on host lawns. The growth conditions therefore affect the capacity of the bdellovibrios to attach to and lyse host organisms. A proteolytic exoenzyme formed by certain bdellovibrio strains digested heat-killed, acid-treated or EDTA-treated host organisms, but did not affect intact host organisms. High phosphate concentrations inhibited exoenzyme activity. The morphological sequence of lysis induced by exoenzyme-forming parasitic bdellovibrio strains suggested that this lysis was a two-stage process: the first stage was specific attachment of bdellovibrios with damage to the cell wall of the host organisms ; the second stage was non-specific digestion of cellular components by exoenzyme produced by the bdellovibrios.
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Separation, Characteristics and Minimal Amino-Acid Requirements of Six Variants Derived from a Strain of Bacillus cereus
More LessSUMMARYMaintenance of a stock culture of Bacillus cereus by subculture on nutrient agar plates resulted in dissociation of the culture manifest as the development of fimbriate outgrowths from the initially entire peripheries of confluent streaks and isolated colonies. Auxanographic determination of minimal amino acid requirements of the dissociated culture indicated that it was composed of at least two types of organism: one was sensitive to (i.e. probably lysed by) l-lysine and the other resistant. They were further separated on the basis of sensitivity to lysine and colonial morphology into six different types. The microscopic appearance of organisms and their arrangement within colonies indicated that the original culture and each of the variants was a rough (R) type. At 28°, four variants required only l-glutamate for growth, while the remaining two required l-cysteine or l-α-alanine in addition. At 35° a greater number of amino acids had to be supplied for growth to occur. At neither temperature did the variants show a requirement for growth factors of the vitamin B-complex. These nutritional requirements, together with infrared spectra of whole organisms and biochemical characteristics determined by conventional methods, confirmed that each variant, though showing minor differences, did represent a culture of B. cereus. On auxanographic plates in the presence of l-lysine at 28°, three variants were lysed, one was unaffected, and the growth of two enhanced.
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An Alcaligenes Species with Distinctive Properties Isolated from Human Sources
More LessSUMMARYThe distinctive properties of an Alcaligenes-like organism isolated from human pathological material are described. The organism is readily recognizable by its characteristic colonial appearances, fruity smell and greening of blood agar. It resembles to a considerable extent Alcaligenes faecalis, ‘Bacterium alcali-aromaticum’, and A. odorans; the name A. odorans var. viridans is proposed for the organism. It appears to be non-pathogenic, but may be confused with Pseudomonas aeruginosa.
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A Comparative Study on the Biochemical Bases of the Maximum Temperatures for Growth of Three Psychrophilic Micro-Organisms
More LessSUMMARYThree psychrophilic micro-organisms (strains of Arthrobacter, Candida and Corynebacterium erythrogenes) were capable of growth for a period when exponential-phase cultures in chemically defined media were transferred from temperatures at or near the optima for growth (20, 10 and 15°, respectively), to 37,25 and 30°, respectively. The latter temperatures were 3–5° above the maxima for the growth of the organisms in freshly inoculated cultures. Growth at the higher temperatures was greatest with the Candida and least with the Arthrobacter. Cultures of the Arthrobacter and Candida grew when transferred back to the optimum temperatures for growth, after a lag which increased with the length of time that the cultures had spent at the higher temperatures. C. erythrogenes cultures grew almost immediately after they were transferred back to the optimum growth temperature. Growth of the organisms at the higher temperatures was not affected by supplementing cultures with bacteriological peptone and/or yeast extract. There was a rapid decline in the viability and in the rates of respiration of endogenous reserves and of exogenous glucose and pyruvate when Arthrobacter and Candida cultures were transferred to the higher temperatures. But with C. erythrogenes the respiratory activities were not so markedly affected by the change in incubation temperature, while the viability of this bacterium increased slightly after the transfer of cultures to the higher temperature. The activities of many of the tricarboxylic acid cycle enzymes in Arthrobacter and Candida were diminished after the transfer of organisms from the optimum temperature to one above the maximum for growth; but the activities of these enzymes in C. erythrogenes were less affected by the change in incubation temperature. There was no marked intracellular accumulation or excretion of ultraviolet-absorbing compounds by the organisms after the transfer of cultures to the higher temperatures. The results are discussed in relation to the biochemical factors which may determine the maximum temperatures for growth of these organisms.
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Growth abnormalities in Hfr Derivatives of Escherichia coli Strain c
I. SASAKI and G. BERTANISUMMARYFrom Escherichia coli strain c, made F+ by infection with the sex factor F normally carried by E. coli strain k-12, several Hfr (‘high frequency of recombination’) strains were derived. Among these, four were found which exhibited a defective growth pattern on minimal media at 37°. Reversion to the F+ state was accompanied by re-establishment of normal growth habit. In the case best studied (strain c-132) the Hfr bacteria form colonies smaller than normal, acquire a rough surface upon prolonged incubation, and are unable to grow at 42°. Growth is normal at room temperature and on rich media; it can be improved by the addition of methionine to minimal media. The rate of reversion from the Hfr to the F+ state (i.e. from defective to normal growth) is of the order of 1/20,000 per generation. Defective growth is not due to a genetic peculiarity of the F factor, nor is it dependent on the map location of the ‘ origin’ or leading end of the particular Hfr strain, or on its direction of chromosome transfer; possibly it results from the manner in which the F factor is integrated at any given chromosomal site.
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Mutations in Symbiotic Effectiveness in Rhizobium trifolii Caused by Transforming DNA and Other Agents
More LessSUMMARYA strain of Bhizobium trifolii able to fix nitrogen in root nodules of clover plants lost its effectiveness when treated with deoxyribonucleic acid (DNA) from an ineffective strain. Attempts to transform two ineffective strains to effectiveness failed, even when the donor of DNA and the recipient strains were genetically related and apparently differed only in symbiotic property. The efficiency of transformation by DNA to ineffectiveness was compared with mutagenic and selective treatments. The results support the idea that symbiotic effectiveness involves compatability between several plant and bacterial factors, changes in any one of which makes the bacterium ineffective.
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Carbohydrate Metabolism of Iron-Rich and Iron-Poor Staphylococcus aureus
More LessSUMMARYComparative studies were made of the metabolic activities of a strain of Staphylococcus aureus grown in iron-poor and iron-rich trypticase medium, with and without glucose. Four nutritionally distinctive types of organisms were produced: iron-rich without glucose (Fe + G –); iron-poor without glucose (Fe– G –); iron-rich with glucose (Fe + G + ); iron-poor with glucose (Fe– G+). Fe+ G– cocci oxidized glucose, l- and d-lactate, pyruvate, acetate, formate, and Krebs cycle intermediates to completion. Of these substrates, only glucose and the lac-tates were oxidized by the Fe– G– organisms. These latter oxidations proceeded at decreased rates and incompletely to acetate and acetoin. Fe+ G+ cocci in comparison with the Fe+ G– cocci showed glucose inhibition of oxidative capacity by metabolizing only glucose, L-lactate and pyruvate to acetate and failing to oxidize d-lactate, acetate and Krebs cycle intermediates. The Fe– G+ cocci showed the most severe restriction of oxidative capacity by oxidizing only glucose with the accumulation of much lactate and minor amounts of pyruvate, acetate and acetoin. The Fe – G –, Fe – G +, and Fe + G + cocci glycolysed glucose at comparable rates, while the highly oxidative form Fe+ G– showed a markedly decreased glycolytic activity. The catalase activity of both types of iron-poor cocci was very much lower than that of the iron-rich organisms. Of the latter, the Fe+ G+ cocci showed a catalase activity only 20% that of Fe + G – cocci.
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On the Function and Structure of the Septal Pore of Polyporus rugulosus
More LessSUMMARYMicrographs of serial sections of Polyporus rugulosus Lev. show minute and regularly spaced pore-cap perforations which are of similar dimensions to nuclear membrane pores. The presence of two types of pore apparatus in Basidiomycetes is established, and suggestions are made about the function and evolutionary development of the septal pores of Basidiomycetes.
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The Role of Lomasomes in Wall Formation in Penicillium vermiculatum
More LessSURMMARYWhen ascospores are formed within the ascus each nucleus and associated cytoplasm becomes enclosed by a cell wall. The origin of this wall is traced in a soft cleistothecial species, Penicillium vermiculatum Dangeard. Asci in this fungus arise by budding, and some aspects of bud-wall formation are recorded here.
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The Chemical Composition of the Nucleic Acids and Other Macromolecular Constituents of Mycoplasma mycoides var. capri
More LessSURMMARYSamples of deoxyribonucleic acid (DNA), microsomal ribonucleic acid (RNA) and a neutral polysaccharide from Mycoplasma mycoides var. capri were isolated and analysed. The DNA was found to have an adenine + thymine/guanine + cytosine value of 3·04, and the RNA to have an adenine+ uracil/guanine + cytosine value of 1·21.
The amino acid composition of the protein of the organism was also determined and found to be in close agreement with the values expected by extrapolating the curves obtained from the amino acid contents of the protein of several bacteria having DNA’s with a wide range of adenine + thymine/guanine + cytosine values ( Sueoka, 1961 ). The values were also in close agreement with those obtained for the protein of Tetrahymena pyriformis, which has a DNA of similar base composition (A + T/G + C = 3·0). Two significant exceptions were noted: the value for proline was almost twice as large as would have been expected and a large amount of cysteine was found.
The mycoplasma organisms contained a very small amount of a neutral polysaccharide in which only glucose was detected.
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A Comparison by the Use of Gel Electrophoresis of Soluble Protein Components and Esterase Enzymes of some Group D Streptococci
More LessSURMMARYSoluble cell constituents of strains of Streptococcus faecalis, S. faecium and S. durans were studied by electrophoresis in polyaery lamide gels followed by staining the gel to reveal the patterns of separated proteins and esterase enzymes. The patterns of proteins and of esterases found in S. faecalis differed from those in S. faecium and S. durans. Strains of S. faecalis differing in serotype and variety showed a very similar series of proteins, some differences in patterns of esterases were found, but similar patterns occurred in strains differing in type and variety. The major protein bands of S. faecium and S. durans differed in mobility from the major proteins of S. faecalis; different strains of S. faecium and S. durans showed some differences in other protein bands. Esterase activity of S. faecium and S. durans was weaker than that of S. faecalis, and in the case of most strains only faint esterase bands were detected. A strain of S. faecium which gave protein and esterase patterns different from those of the remaining strains, differed also in showing motility.
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The Role of Phage in the Transduction of the Toxinogenic Factor in Corynebacterium diphtheriae
More LessSURMMARYStrains of Corynebacterium diphtheriae which produced large amounts of toxin (e.g. pw8) were found to be non-lysogenie, but they contained a cytoplasmic toxinogenic factor designated as T+. After infection with phage they produced less toxin. It is possible to remove the phage from the lysogenic strains without affecting the T+ factor by treatment with small amounts of acriflavine. When treated with larger amounts of acriflavine the T+ factor was also removed, rendering the strain non-toxinogenic. The toxin-inducing phages can be converted in vitro into non-toxinogenic phages by treatment with small amounts of acriflavine. After passage through the pw8t + strains these phages revert to toxin-inducing ability. Similarly, the naturally occurring, non-toxinogenic γ phage can be made to induce toxin production. This indicates that the role of phage in diphtheria toxin production is to transduce the T+ factor.
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Interaction between Phytophthora infestans and Tissue Cultures of Solanum tuberosum
More LessSURMMARYIt has been shown that tissue cultures of Solanum tuberosum var. Majestic (susceptible) stimulated the growth of Phytophthora infestans. A similar stimulus was produced by cell suspensions of the S. tuberosum var. Orion (resistant), but was not manifested by larger tissue aggregates of this variety. The failure of Orion tissue aggregates to stimulate was independent of the size of the fungal inoculum and was annulled by boiling the Orion tissue. Freezing of both Majestic and Orion tissue aggregates destroyed the stimulus, but freezing followed by boiling or boiling followed by freezing did not. It is suggested that the failure of living Orion tissue aggregates to stimulate the growth of P. infestans was a direct effect of their excluding the fungus.
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