- Volume 129, Issue 3, 1983
Volume 129, Issue 3, 1983
- Biochemistry
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Isolation of β-Amyrin from the Fungus Aspergillus nidulans
More LessThe pentacyclic triterpene alcohol β-amyrin, which is commonly found in plants, was isolated from wild-type cultures of the ascomycete fungus Aspergillus nidulans. The isolated β-amyrin was characterized by TLC, GLC, and HPLC and produced identical mass and 1H NMR spectra to those of authentic β-amyrin. This material was isolated from static (non-shaking) cultures.
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β-N-Acetylhexosaminidases of Physarum polycephalum: Some Characteristics of a New Form of the Enzyme
More LessDuring axenic growth, microplasmodia of Physarum polycephalum secreted chitinase and β-N-acetylhexosaminidase. Chitin added to the medium was depolymerized to N-acetylglucosamine, but this was not used for growth. Spent culture medium contained three enzymes with activity towards 4-methylumbelliferyl-β-N-acetylglucosaminide and these were separated by chromatography on DEAE-cellulose. In previous work β-N-acetylhexosaminidases X and Y were identified. The latter form has now been resolved to yield a new form Z. The Y form can be readily distinguished from both X and Z by its lack of activity towards N,N′-diacetylchitobiose. Comparison of β-N-acetylhexosaminidases X and Z revealed differences in thermal stability, pH optima and K m values. 3,4-Dinitrophenyl-tetra-N-acetylchitotetraoside is hydrolysed by β-N-acetylhexosaminidase Z, but not by the X form of the enzyme.
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A Thiol Inhibitor Produced by Aspergillus niger
More LessA low molecular weight inhibitor of the thiol proteases papain and bromelain has been identified and partially purified from the culture filtrates of Aspergillus niger. Further studies have shown that this inhibitor reacts with compounds containing a free thiol group and as such it is capable of inhibiting other enzymes that contain a functional thiol group at their active site.
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The Essential Role of Diaminopimelate Dehydrogenase in the Biosynthesis of Lysine by Bacillus sphaericus
More LessExtracts of Bacillus sphaericus NCTC 9602 catalysed the formation of meso-diaminopimelate from aspartic β-semialdehyde plus pyruvate, or from dihydrodipicolinate, even though no activities of tetrahydrodipicolinate acetylase (or succinylase) nor N-acetyl-(or N-succinyl-)ll-diaminopimelate deacylase nor diaminopimelate epimerase were found. However, meso-diaminopimelate d-dehydrogenase was present, and had very high activity at pH 7.5 in the direction of synthesis of meso-diaminopimelate from tetrahydrodipicolinate. A lysine-requiring mutant of B. sphaericus lacked diaminopimelate dehydrogenase, and this enzyme reappeared in a revertant that grew without lysine. Other lysine-requiring auxotrophs were defective in dihydrodipicolinate synthase or dihydrodipicolinate reductase or diaminopimelate decarboxylase, but had diaminopimelate dehydrogenase. Diaminopimelate dehydrogenase is not important in the assimilation of ammonia. Mutants that lack this enzyme or else cannot make one of its substrates (tetrahydrodipicolinate) still grow rapidly in minimal medium (plus 0.7 mm-l-lysine) containing ammonium chloride (36 mm) as the only major source of nitrogen. The wild-type grew with l-glutamine, but not with glutamate or lysine as sole source of nitrogen.
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Role of Primers in Glucan Synthesis by Glucosyltransferases from Streptococcus mutans strain OMZ176
More LessThe effects of isomaltosaccharides of various molecular weights (isomaltose to dextran T2000) on glucan synthesis by a water-soluble glucan-synthesizing glucosyltransferase enzyme (GTase-S) and a water-insoluble glucan-synthesizing enzyme (GTase-I), both from Streptococcus mutans OMZ176, were examined. The activity of GTase-S was not affected by the addition of the isomaltosaccharides, but GTase-I was stimulated increasingly by isomaltosaccharides with degrees of polymerization more than 10. The GTase-I activity first increased and thereafter decreased slightly with increasing amounts of a soluble dextran. Maximal stimulation occurred at concentrations in the range 0·1 to 0·2 mg ml−1, when dextran T10 was used as a primer. The rate of glucan synthesis was highly enhanced by the combined action of GTase-S and GTase-I. The profile of the net activity of GTase-I in the presence of various amounts of GTase-S was similar to that of GTase-I in the presence of increasing amounts of an exogenous dextran. These results collectively suggest that soluble glucan produced by GTase-S from sucrose acts as an intrinsic primer for the glucan synthesis by GTase-I, indicating the contribution of autopriming in glucan synthesis by crude GTase of S. mutans.
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Studies on the Mechanism of Intrinsic Resistance to β-Lactam Antibiotics in Group D Streptococci
More LessSix penicillin-binding proteins (PBPs) were detected in clinical isolates of each one of three group D streptococci: Streptococcus bovis, S. faecalis and S. faecium. When examined in whole organisms, the PBPs of S. faecium, the most penicillin-resistant species of group D streptococci, generally had lower affinities for the antibiotic than those of S. faecalis (intermediate penicillin resistance), which in turn were of lower affinity than those of S. bovis (penicillin-sensitive): On the other hand, no quantitative correlation could be established between the binding of penicillin to any one PBP or group of PBPs, and the penicillin MIC value for the corresponding micro-organism. Examination of the amounts of antibiotic bound and the rates of binding to PBPs of equal numbers of protoplasts and whole bacteria of S. faecalis and S. faecium, indicated that there was no permeability barrier to benzylpenicillin in the cell walls of these species. The lower antibacterial effectiveness of cephalothin compared with ampicillin in group D streptococci was paralleled by the higher concentrations of cephalothin needed in competition assays to inhibit the lower molecular size PBPs of these bacteria.
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Studies on Outer Membrane Proteins of Moraxella nonliquefaciens
More LessOuter membrane fractions of Moraxella nonliquefaciens 7784 strains SC-c and N-b, isolated by extraction with lithium acetate, were analysed by SDS-PAGE. Three main proteins were found, of which one, with an apparent molecular weight of 19500, was undetectable in membranes isolated by lysis of lysozyme/EDTA spheroplasts. All three major proteins were heat modifiable.
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Colicin E4-CT9 is Proteolytically Degraded after Discharge from Producing Cells in Liquid Cultures
More LessColicin E4 was produced in very large amounts when Escherichia coli K12 strain W3110 pColE4-CT9 was grown in the presence of 0.5 μg mitomycin C ml−1. The colicin was discharged from the producing cells when they lysed and was then degraded by a protease located on the surface of the producing cells. Colicins and proteolytic fragments derived from them could be concentrated from spent culture medium by filtration through Millipore membrane filters. Colicins are probably retained by these filters by hydrophobic interactions since binding was unaffected by changes in ionic conditions but-was completely inhibited in the presence of ionic or non-ionic detergents.
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Isolation of a Characteristic Phthiocerol Dimycocerosate from Mycobacterium leprae
More LessA characteristic mycobacterial wax, phthiocerol dimycocerosate, has been isolated from liver of armadillos experimentally infected with Mycobacterium leprae. The structure of this wax is generally similar to that produced by Mycobacterium tuberculosis, but the homologous phthiocerol and the mycocerosic acid components from M. leprae are significantly different from those of M. tuberculosis.
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- Development And Structure
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Complex Carbohydrates in the Cyst Wall of Histriculus similis
More LessA cytochemical and structural study of the cyst wall of Histriculus similis has been carried out. Application of cytochemical methods for complex carbohydrates indicated that the mesocyst is rich in sulphated glycosaminoglycans. The endocyst and granular layer contained neutral and sulphated glycoproteins, respectively.
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- Ecology
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The Influence of Growth Rate and Nutrient Limitation on the Microbial Composition and Biochemical Properties of a Mixed Culture of Oral Bacteria Grown in a Chemostat
A sample of human dental plaque was homogenized in transport fluid and inoculated simultaneously into a glucose-limited and a glucose-excess chemostat maintained at pH 7·0 and a dilution rate (D) of 0·05 h−1. In an attempt to ensure the establishment of slow-growing bacterial populations, two further inoculations of each chemostat with fresh samples of dental plaque took place before a steady-state was attained at this dilution rate. The dilution rate was increased step-wise to D = 0·6 h−1, and then returned directly to D = 0·05 h−1. Contrary to chemostat theory, microbial communities with a high species diversity were maintained under all of the experimental conditions employed, although not all of the bacterial populations present in the inocula established successfully in the chemostat. At each steady-state the bacteriological composition and biochemical properties (fermentation products, enzyme assays and acid production) of the communities of each chemostat was determined. Higher cell yields and a slightly more diverse community were obtained from the glucose-limited chemostat at all dilution rates. A complex mixture of end products of metabolism was obtained from the glucose-limited chemostat, suggesting amino acid catabolism, while lactate was the predominant acid of the glucose-excess culture. In washed-cell experiments, communities from the glucose-excess chemostat produced the lower terminal pH values following a pulse of glucose, with the lowest pH values occurring at the higher dilution rates. A film of micro-organisms, which accumulated around the neck of the chemostat, was sampled at the end of the experiment. The microbial composition of the films from each chemostat differed markedly, and both were different to the community of the bulk fluid of the respective chemostat. Spirochaetes and a population of yeasts were detected in the films from the glucose-limited and glucose-excess chemostats, respectively. No invertase or glucosyltransferase activity, and little glucoamylase-specific glycogen was detected in the communities from either chemostat, although significant endogenous activity, particularly at high dilution rates, was obtained with washed-cells from the glucose-excess chemostat. The results suggest that the chemostat could make a valuable contribution to the study of the ecology of dental plaque.
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Effect of Bentonite Clay on the Growth of Gaeumannomyces graminis var. tritici and on its Interactions with Antagonistic Bacteria
More LessThe effects were studied of increasing concentrations of bentonite clay on the interactions between the fungal pathogen Gaeumannomyces graminis var. tritici and two bacterial antagonists. Clay increased the growth rate of G. graminis; this increase was statistically significant, though small, and could have been due to an effect on water availability. The effectiveness of one of the bacterial culture nitrates in restricting the fungal growth was reduced by the clay, though antagonism was maintained in the presence of bacterial cells. The clay may adsorb some of the bacterial toxins, and lowered water availability may increase bacterial antagonism before it significantly reduces fungal growth. Antagonism by the other bacterium was not affected by clay.
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Tropic Responses of Fungi to Wood Volatiles
More LessSapwood blocks of lime (Tilia vulgaris) and pine (Pinus sylvestris) placed to one side of growing colonies of several wood decay fungi markedly influenced their hyphal extension patterns, particularly by causing positive or negative tropic responses. A method was devised to measure and quantify these responses and analyse them statistically. Chemotropic responses were demonstrated by Chaetomium globosum, Trichoderma viride, Serpula lacrymans and Coniophora puteana in the presence of air-dried and heat-dried wood but not by Coriolus versicolor or Humicola grisea. The implications of chemotropism as a factor influencing the invasion and colonization of wood are discussed.
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- Genetics And Molecular Biology
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Transformation In Escherichia coli: Studies On The Role Of The Heat Shock In Induction Of Competence
More LessEscherichia coli can be rendered competent for DNA uptake by exposure to a heat shock in the presence of divalent cations. We have studied the influence of variations of the incubation temperature in the competence regimen on the efficiency of competence induction, i.e. the efficiency of uptake of DNA into a DNAase resistant form. For cells grown at 37 °C DNA uptake occurs (1) during a heat shock from 0 °C to temperatures between 15 °C and 42 °C (optimal, 30 °C) and (2) after a heat shock from 0 °C to temperatures between 20 °C and 42 °C (optimal, 32 °C) and a subsequent cold shock to 0 °C. Under the latter conditions DNA uptake occurs during incubation of the transformation mixture at 0 °C after the heat shock. In both cases the efficiency of DNA uptake increases as the incubation temperature during the heat shock increases from about 18 °C to about 32 °C. When recipient cells are grown at 22 °C instead of at 37 °C, the temperature range at which competence induction occurs is shifted by 5 °C to lower temperatures. These results indicate that phase transitions of membrane lipids may play a critical role in induction of competence. When recipient cells are shocked from high temperature to low temperature, leakage of the periplasmic β;-lactamase occurs; the degree of leakage and the efficiency of competence induction are affected similarly by the temperature range of the shock. This observation indicates that phase transition of membrane lipids causes damage to the outer membrane, and that this damage may be essential for induction of competence.
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Hybrid Plasmids Containing The Pyruvate Dehydrogenase Complex Genes and Gene-Dna Relationships In The 2 To 3 Minute Region Of The Escherichia Coli Chromosome
More LessA sample of colonies from the Clarke-Carbon Co1E1-Escherichia coli DNA plasmid gene bank was screened by conjugation for complementation of the lipoamide dehydrogenase lesion of a deletion strain lacking all components of the pyruvate dehydrogenase complex, Δ(aroP aceE aceF lpd). Two Co1E1-lpd + hybrid plasmids were identified: pGS2 (Co1E1-ace lpd +; 24 kb) and pGS5 (Co1E1-lpd +; 14 kb). Enzymological studies confirmed that pGS2 expressed all the activities of the pyruvate dehydrogenase complex, whereas pGS5 expressed the lipoamide dehydrogenase and acetyltransferase activities (the latter from a ColE1 promoter). These and other plasmids were used to construct a 47-site (15 enzymes) restriction map for a 24·2 kb segment of bacterial DNA in the nadC-lpd region. A futher 13 sites (six enzymes) were defined in a 5·4 kb sub-segment containing the lpd gene. γ phage derivatives containing specific fragments were constructed and used in transduction studies which located the ace and lpd genes in a 7·78 kb sub-segment flanked by AccI and NruI sites.
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Control of recA dependent activities in Escherichia coli: a possible role for the recF product
More LessDNA repair and genetic recombination have been studied in recF143 mutants of Escherichia coli in which expression of inducible, SOS repair activities was altered by additional mutations either in lexA or recA.recF143 and lexA3 appeared to act additively to increase sensitivity to UV irradiation and to reduce recombination proficiency. The recF defect was suppressed in strains carrying the tif-1 allele of recA but not in strains carrying mutations that increased synthesis of recA + protein or which directly inactivated lexA repressor. These and other data are interpreted to suggest that the recF defect is related to a reduced activity of recA protein. The implications of these findings are discussed in relation to the control of SOS activities and cell division during normal growth.
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Bacillus subtilis Strains Carrying Two Non-Tandem Duplications Of The trpE-ilvA and the purB-tre Regions Of The Chromosome
More LessBacillus subtilis strains possessing the trpE30 marker (splitting of the trpE locus and a non-tandem duplication of chromosome segment Ib: purB-tre) when transformed or transduced to tryptophan independence mainly give rise to haploid cells with the genetic structure of strain 168. However, among the Trp+ transformants or transductants about 10% are merodiploid carrying a non-tandem duplication of segment C (trpE-ilvA) while maintaining that of segment Ib. Linkage and segregation studies made it possible to determine their genetic structure, which can be represented by three different maps. In map a the copies of Ib are inverted repeats and one of them is flanked by two direct repeats of segment C; in map b two Ib-C segments are inverted repeats and in map c the copies of C are inverted repeats with one of them flanked by direct repeats of Ib. It is proposed that transition from map a to map b and then to map c, and vice versa, may occur by recombination between inverted repeats of either Ib or C. The merodiploids are unstable, recombination between direct repeats leading to haploid cells of 168-type structure. The models proposed for merodiploid formation call for fusion of two recipient chromosomes mediated by the donor segment and recombination between copies of a DNA sequence of the two chromosomes located in different regions. In the case of PBS-1 mediated transduction the greater length of the donor DNA segment makes it possible to obtain the merodiploids with a single recipient chromosome and this needs only a slight modification of the models. No trpE30 + merodiploids are found in transformation when the recipient carries a deletion of the SPβ prophage, or in transduction when both donor and recipient possess this deletion. These results indicate that the homologous sequences involved may be part of the SPβ prophage or that a sequence of bacterial DNA has a good homology with it.
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Genetic Mapping in Methylophilus methylotrophus AS1
More LessPrime plasmids have been isolated from Methylophilus methylotrophus AS1 using the IncP-1 plasmid pMO172. Such plasmids can complement mutant function when transferred to appropriate strains of Pseudomonas aeruginosa PAO. From the range of particular functions complemented by each prime plasmid, a preliminary map of the M. methylotrophus AS1 genome with four groups of linked markers was obtained. Physical examination of two of these prime plasmids showed that each had acquired an additional DNA segment. Southern hybridization experiments showed there was sequence homology between the additional DNA segments and M. methylotrophus AS1 DNA, confirming that these prime plasmids carried a segment of the M. methylotrophus AS1 genome. Mapping by complementation may be applicable to other bacteria in which mutants suitable for selecting recombinants are not readily available.
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Relationship of the Replication and Incompatibility Genes of an IncFVI Haemolysin Plasmid with Other F-like Haemolysin Plasmids
More LessThe replication and incompatibility region of the IncFVI plasmid pSU502 has been isolated by in vitro DNA manipulation as part of a 12·6 kb plasmid, denominated pSU503. Plasmid pSU503 was strongly incompatible with its parental plasmid, pSU1, but was fully compatible with the haemolytic plasmids pSU316 (IncFIII/IV), pHly152 (IncI2) and pSU233 (Inc-pSU233). Furthermore, the 6.9 kb EcoRI fragment of pSU503 which carries the replication and incompatibility determinants of pSU1 did not show any detectable homology (<70 %) with any of the haemolysin-determining plasmids with which it is compatible. Thus, homologous haemolysin determinants have become linked to apparently unrelated replicons.
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- Pathogenicity And Medical Microbiology
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A Rapid Bioluminescence Method for Quantifying Bacterial Adhesion to Polystyrene
More LessBioluminescence ATP analysis has been used to assess bacterial adhesion with hydrophobic polystyrene tubes as the attachment surface. The assay was performed at 37 °C and pH 6.8 with a 10 min incubation period. A variation of more than 200-fold was observed in the adherence capacity of 34 urinary isolates of Escherichia coli, and organisms could be classified as strongly or weakly adherent. All strains capable of strong adhesion possessed both type 1 fimbriae and flagella, and maximum adhesion was expressed during the exponential growth phase. Attachment was in all cases virtually eliminated by addition of 2.5% (w/v) d-mannose to the incubation buffer. Conversely, strains which were deficient in type 1 fimbriae or flagella, or both, were weakly adherent during all phases of growth. There was no correlation between adherence of E. coli to polystyrene and adherence to buccal or uroepithelial cells, but there was a significant association with adherence to uromucoid (P < 0.002).
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Analysis of Polypeptides of Mutants of Mycoplasma pneumoniae that Lack the Ability to Haemadsorb
More LessHaemadsorption-negative mutants of Mycoplasma pneumoniae were isolated which varied in their capacity to adsorb erythrocytes of various animal species suggesting adherence to erythrocytes is mediated by different binding mechanisms. Trypsin treatment of the wild-type strain resulted in loss of haemadsorbing activity; several polypeptides, some of which regenerated with haemadsorbing activity following further incubation, were also trypsin sensitive. The haemadsorption-negative mutants could be divided into two groups according to their polypeptide pattern. In the first group (11 mutants) the PAGE pattern was identical to that of the wild-type strain. The second group comprised 7 mutants which differed from the wild-type by lack of one or more polypeptides with molecular weights of 190000, 90000 or 40000. During growth attachment to glass was weak or absent in the mutants. Surface hydrophobicity as measured by hydrophobic-interaction chromatography was nearly comparable in mutants and parent strain.
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Antibody Responses to Antigens of Streptococcus mutans in Monkeys (Macaca fascicularis) Immunized against Dental Caries
More LessImmunization of rabbits or monkeys with walls prepared from Streptococcus mutans by a procedure including extraction with SDS at room-temperature induced antibodies to three antigens (A, B and C) detectable by crossed Immunoelectrophoresis. Antigens A and B have previously been characterized as proteins of molecular weight 29000 and 190000, respectively. Antigen C was characterized as having a molecular weight of 70000 and was purified by immunosorbent affinity chromatography and hydrophobic interaction chromatography. Another wall protein, antigen D, of molecular weight 13000, was extracted from walls with Triton X-100. Immunization of monkeys with walls prepared from cultures of S. mutans grown at a high (D = 0.5 h−1) or low (D = 0.05 h−1) dilution rate in a chemostat showed that only the latter induced protection against dental caries. There was a positive correlation between levels of antibody to antigens A and C and induction of protection and a negative correlation between protection and the level of antibody to antigen B. No antibody to antigen D was detected in protected monkeys and an experiment in which monkeys were immunized with pure antigen D confirmed that it does not induce protection.
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- Physiology And Growth
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The Effects Of Methanol, Ethanol, Propanol and Butanol On Bacterial Attachment To Surfaces
More LessThe effects of methanol, ethanol, propanol and butanol, at concentrations of 0·2, 0·5, 1·0, 1·5 and 2·0 % (v/v), on the attachment of a marine Pseudomonas sp. to polystyrene dishes (PD) and tissue culture dishes (TCD) were determined. When the bacteria attached in the presence of the alcohols, attachment to TCD was increased with certain concentrations of ethanol (0·2 and 0·5 %), propanol (0·2, 1·5 and 2·0 %) and butanol (1·0 %), with either a decrease in attachment or no effect with the other concentrations tested. With PD, there was no increase in attachment, but the relationship between numbers of attached bacteria and alcohol concentration paralleled that obtained with TCD. Pre-incubation of the bacteria with the alcohols affected their subsequent attachment, but the resultant increases or decreases in attachment were not consistent with those obtained when attachment occurred in the presence of alcohols. Physicochemical properties of the attachment system were evaluated by measuring liquid Surface tensions (γLV) and sessile drop (θSD) and air bubble (θB) contact angles on TCD and PD of the bacterial suspending medium with the various alcohol concentrations, both before and after incubation with the alcohols. There was a relationship between numbers of attached bacteria and medium γLV, with minimum attachment occurring at γLV, values of 64-69 mN m−1. The increase in attachment to TCD in the presence of ethanol, propanol and butanol was accompanied by an increase in respiration rate, which could reflect a modification of cell surface components.
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Growth Of Streptococcus Pyogenes and Streptolysin O Production In Complex and Synthetic Media
More LessA comparative study of the growth of a highly haemolytic group A streptococcal strain in Trypticase-yeast extract medium and in a chemically defined medium was undertaken. Appreciable growth was obtained in the latter medium with the release of significant amounts (120 haemolytic units) of streptolysin O. This indicates that toxinogenic factors present only in the peptones of complex media are not essential for biosynthesis and release of this cytolytic toxin, as is the case for many bacterial toxins. NADase was also released in the synthetic medium. Bacterial cell mass, growth rate, and streptolysin O production were threefold higher in the complex medium. The effects of various carbohydrates on streptolysin O production in complex medium are investigated. No repression of toxin formation by glucose was observed. The relationship between growth and toxinogenesis in streptococci and in other toxinogenic bacteria is discussed.
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The Role Of Limited Respiration In The Incomplete Oxidation Of Glucose By Saccharomyces Cerevisiae
More LessThe respiratory capacity of Saccharomyces cerevisiae growing in continuous culture on glucose and on mixtures of glucose and ethanol was investigated. An oxygen uptake rate of 8 mmo1 g−1 h−1 was found to limit the ability of the organism to degrade a substrate purely oxidatively. On glucose as sole energy and carbon source, this respiration rate was invariably achieved at an identical growth rate and thus at an identical substrate uptake rate when the inlet glucose concentration was varied. The rate of ethanol co-consumption together with glucose was strictly governed by this limiting maximum respiratory capacity and no repression of respiration was observed at dilution rates where ethanol was excreted by the cells. Hence, a limitation in some step in the oxidative branch of catabolism is likely to be responsible for incomplete oxidation of glucose at high growth rates rather than an undefined action of glucose repression.
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Modifications of Cell-wall Polysaccharides during Stipe Elongation in the Basidiomycete Coprinus cinereus
More LessModifications of cell-wall polysaccharides during stipe elongation in Coprinus cinereus were investigated by gel-filtration and Smith-degradation analyses. During stipe elongation two polysaccharide fractions (I and IVa) decreased in average molecular weight, whereas two other fractions (II and III) increased marginally in molecular weight. The decreases in molecular weight of the former fractions were accompanied by changes in glycosidic linkage composition. Glucans comprised the bulk of all fractions; additionally there was an appreciable contribution from mannose and xylose in fraction II. The results are discussed in relation to the mechanisms of stipe elongation.
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The Utilization of Nitriles and Amides by Nocardia rhodochrous
More LessNocardia rhodochrous LL100-21 grew on acetonitrile, acetamide, a range of aliphatic nitriles and amides, benzonitrile and benzamide as the sources of carbon and/or nitrogen. It also grew on acetate, several other aliphatic acids, and benzoate as carbon sources. Growth on either acetonitrile or acetamide resulted in induction of both acetonitrilase and acetamidase activities, which were shown to be due to separate enzymes. Growth on benzonitrile resulted in the ability to release ammonia from benzonitrile but not benzamide, acetonitrile or acetamide. Growth on benzamide resulted in the ability to form ammonia from benzamide but not benzonitrile, acetonitrile or acetamide. Measurements of respiratory activity of the bacteria grown on the various substrates showed a similar pattern of induction of oxidative activity for these compounds.
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Glucose-induced Trehalase Activation and Trehalose Mobilization during Early Germination of Phycomyces blakesleeanus Spores
More LessWhen dormant spores of Phycomyces blakesleeanus were activated without concomitant activation of trehalase, breakdown of storage trehalose during early germination was not prevented. Measurement of trehalase activity during early germination of spores activated in this way indicated a subsequent rapid activation of trehalase upon incubation of the spores in germination medium. Trehalase activity reached a maximum after about 10 min of germination; thereafter it declined to values somewhat higher than those found in dormant spores. The same was observed when the activation of trehalase which normally occurs during heat activation of the spores was suppressed by adding long-chain alcohols to the activation medium. These results argue against previous speculation that trehalase is a 73 ‘luxury’ molecule in the spores and that its activation has no significant role in the induction of germination. They point, on the other hand, to an important role for trehalase in the induction of germination. The main factor in the germination medium responsible for the activation of trehalase was found to be glucose. When spores were incubated under conditions in which they reverted to the dormant state, this subsequent trehalase activation was not seen. The increase in trehalase activity was not dependent on protein synthesis. A less pronounced increase was seen with glucose analogues. In the presence of azide the activation was only retarded, whereas in the presence of azide and salicylhydroxamic acid strong inhibition of trehalase activation was observed.
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Isopropyl-Substituted Phenols Have A Different Effect From Other Phenols On The Breaking Of Dormancy By Heat Shock In Phycomyces Blakesleeanus Spores
More LessPhenols are able to lower the temperature of heat activation (breaking of dormancy by heat shock) in Phycomyces blakesleeanus spores. The effect was observed with a series of phenols ranging, according to increasing lipophilic character, from unsubstituted phenol to 2,4-dichlorophenol. However, the concentration required to produce the same effect with each phenol was reduced with increasing apolar character. A linear relationship was obtained between the log of the concentration of each phenol needed to produce a 4 °C shift of the half-activation temperature and the log of its octanol/water partition coefficient. In contrast, the isopropyl-substituted phenols thymol, 2- and 4-isopropylphenol and 3-isopropylcatechol all raised the half-activation temperature of the spores. The same effect was observed with menthol, the unsaturated analogue of thymol. The heat resistance of the spores was lowered by all phenols, including isopropyl-substituted phenols. Although the reason for the anomalous behaviour of isopropyl-substituted phenols is not known, the opposite effect on spore heat activation and spore heat resistance indicates that the activation process of the spores is not linked to the process of spore killing. Therefore, spore activation is not due to some kind of non-specific sublethal protein denaturation, as might have been concluded previously from the fact that many spore activation methods are sublethal treatments.
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Mineral Ion-containing Vacuolar Inclusion Bodies Associated with Ca2+ Deficiency in Oogonia of Saprolegnia diclina and S. terrestris
More LessThe frequency of occurrence of electron-dense vacuolar inclusions in oogonia of Saprolegnia diclina and S. terrestris was significantly greater under Ca2+-deficient culture conditions than under Ca2+-sufficient conditions. Bodies similar to inclusions seen in sections of oogonia were present in debris from living cultures ground up in de-ionized water. Energy dispersive X-ray analysis of inclusions in sections showed the presence of Mg, P, Ca, and Mn in both species and Na, S and Zn in S. diclina. The bodies from ground cultures contained Mg, P, Mn and Zn in both species and Na in S. terrestris.
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Non-coordinate Regulation of Rhizobium Nitrogenase Synthesis by Oxygen: Studies with Bacteroids from Nodulated Lupinus angustifolius
More LessExperimental conditions which allowed liquid suspensions of lupin bacteroids (Rhizobium NZP 2257) to reduce acetylene at high rates were established. At a dissolved oxygen concentration of 2 μm, swirled suspensions of the bacteroids reduced acetylene at a linear rate of 23 ± 5 nmol (mg cell protein)−1 min−1. The kinetics of protein synthesis were measured by pulse labelling with [35S]methionine followed by two-dimensional electrophoretic analysis of cell lysates. When the suspensions were suddenly exposed to air, the rate of synthesis of the two nitrogenase components declined differentially. The decline in the rate of synthesis of the Fe-protein polypeptides resembled that observed for all the nitrogenase polypeptides in Klebsiella pneumoniae ( Eady et al., 1978 ); the rate of synthesis of the MoFe-protein polypeptides, however, showed a much slower decline. Several models are proposed to account for these results.
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Peptidoglycan-degrading Enzymes in Ether-treated Cells of Neisseria gonorrhoeae
More LessThe incubation of peptidoglycan fragments with ether-treated cells of Neisseria gonorrhoeae resulted in breakdown products that showed the presence of previously undescribed lytic enzymes. The properties of an endopeptidase able to hydrolyse peptide-linked bis-disaccharide peptide dimer to monomer units were examined. An exo-N-acetyl-glucosaminidase was also shown to release free N-acetylglucosamine. The breakdown pattern of glycosidically-linked dimer indicated the existence of an endo-N-acetylglucosaminidase. The activities of the latter enzyme and of the endopeptidase were both sensitive to βlactam antibiotics.
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- Short Communication
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Degrees of O-Acetylation and Cross-linking of the Peptidoglycan of Neisseria gonorrhoeae during Growth
More LessThe progress of incorporation of radioactive glucosamine into the O-acetylated and non-O-acetylated sub-units of the insoluble peptidoglycan of growing Neisseria gonorrhoeae was examined. More than 80% of the final degree of cross-linking was achieved within 3 min; the remainder of the process took much longer. Rapid O-acetylation occupied up to 10 min, at which time only about 65% of the maximum value had been reached. There was thus evidence for maturation of peptidoglycan both in regard to cross-linking and to O-acetylation.
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Mycolic Acid Patterns of Four Vaccine Strains of Mycobacterium bovis BCG
Thin-layer chromatography of methanolysates of four widely used vaccine strains of Mycobacterium bovis BCG showed that only one organism had the expected pattern of mycolic acid methyl esters characteristic of Mycobacterium bovis and Mycobacterium tuberculosis. The remaining three BCG strains lacked methoxy mycolic acid.
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- Taxonomy
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Differentiation between Gram-negative Anaerobic Bacteria by Pyrolysis Gas Chromatography of Lipopolysaccharides
More LessLipopolysaccharides extracted by phenol-water from nine strains of Gram-positive anaerobic bacteria (Bacteroides, Fusobacterium and Veillonella), have been examined by means of pyrolysis gas chromatography. Lipopolysaccharides were fragmented into a group of low molecular weight components and four characteristic high molecular fractions probably consisting of hydrocarbons from the lipid part of the material. The latter fractions were specific for each of the genera tested. At the species level characteristic differences were also found although a limited number of strains were tested. Due to the high reproducibility of the technique, the potential of using the method in differentiating Gram-negative anaerobic bacteria was indicated.
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Numerical Taxonomy of Streptococcus
More LessA numerical taxonomic study of strains of Streptococcus, together with representatives of allied genera, showed 28 reasonably distinct phenons. The major areas, with their phenons, were: (a) enterococcal species group (S. faecalis, S. faecium, ‘S. avium’ and a proposed new species ‘S. gallinarum’); (b) paraviridans species group (S. bovis, S. equinus, S. salivarius, ‘S. casseliflavus’, S. mutans, S. raffinolactis and an unidentified Oral Group I); (c) lactic species group (S. lactis including S. cremoris); (d) thermophilic species group (S. thermophilus); (e) viridans species group (S. mitis, S. sanguis, a proposed new species ‘S. oralis’ and ‘S. milleri’); (f) pyogenic species group (S. agalactiae, S. pyogenes, S. equi, ‘S. equisimilis’ including ‘S. zooepidemicus’, and a cluster of Lancefield Group B strains of human origin); (g) parapyogenic species group (S. uberis, ‘S. dysgalactiae’, and a cluster of strains of Lancefield Groups R, S and T). Species of Aerococcus, Gemella, Leuconostoc and Pediococcus are very closely related to the streptococci.
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Numerical Classification Of Mycobacterium Farcinogenes, Mycobacterium Senegalense and Related Taxa
More LessSixteen strains designated Mycobacterium farcinogenes, fifteen Mycobacterium senegalense, and ten Nocardia farcinica were, together with strains of Mycobacterium and Nocardia, subjected to numerical phenetic analyses using 96 unit characters. The data were examined using the simple matching (S sm), Jaccard (S J) and pattern (D P) coefficients and clustering achieved using the unweighted average linkage algorithm. Cluster composition was not markedly affected by the coefficient used or by test error, estimated at 2.5%. The N. farcinica strains formed a distinct and homogeneous cluster in an aggregate taxon corresponding to the genus Nocardia. The M. farcinogenes and M. senegalense strains were recovered in well-defined and homogeneous phena within the genus Mycobacterium. Mycobacterium senegalense consistently showed a high overall similarity with clusters equated with M. chelonei and M. fortuitum, while the M. farcinogenes cluster was not closely associated with any of the mycobacterial clusters. The results are discussed in the light of other developments in the taxonomy of the bovine farcy bacteria.
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Immunodiffusion Analyses of Mycobacterium farcinogenes, Mycobacterium senegalense and Some Other Mycobacteria
More LessThirty-one strains of Mycobacterium farcinogenes and M. senegalense were analysed together with twenty-five strains representing ten mycobacterial species. The comparative immunodiffusion technique was employed, using two reference systems, one for M. farcinogenes and the other for M. senegalense. The results indicate that the slow growing M. farcinogenes and the fast growing M. senegalense strains are closely related and can not be separated into two clearly distinct clusters. Both species were closely related to M. fortuitum, including strains designated ‘M. peregrinum’ but clearly different from other tested mycobacterial species. The serological data are consistent with the classification of M. farcinogenes and M. senegalense, and possibly M. fortuitum, in a single species. The results are discussed within the context of other taxonomic analyses of M. farcinogenes and M. senegalense.
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- Corrigenda
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