- Volume 129, Issue 2, 1983
Volume 129, Issue 2, 1983
- Obituary
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- Article
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Two Separate Genes Involved In Sulphate Transport In Escherichia coli K12
More LessIn the course of the experiments described above it became clear that the two cys mutations used were not identical. The cysA471 mutation was isolated by Tully (1976) as conferring resistance to chromate, the cysZ474 mutation arose spontaneously and simultaneously with a ptsI mutation, (it may be the result of an inversion with ends in these two genes). The mapping of the genes (see above, Table 3) shows that cysA and cysZ lie on opposite sides of ptsI. We therefore investigated the biochemical nature of the mutations.
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- Biochemistry
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Environmental Factors Affecting The Formation Of Mesityloxide, Dimethylallylic Alcohol And Other Volatile Compounds Excreted By Anabaena cylindrica
More LessAnabaena cylindrica excretes a large number of volatile products. The major components are dimethylallylic alcohol and mesityloxide, while the minor components detected include various nor-carotenoids and lipid degradation products. The formation of mesityloxide is strictly light-dependent, and ceases in the dark. A direct association with photosynthesis can be ruled out since 3-(3, 4-dichlorophenyl)-1,1-dimethylurea (DCMU) does not affect the formation of mesityloxide during the first hour after application, but immediately inhibits the evolution of oxygen.
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The Bactericidal Action Of β-Lactam Antibiotics on an Autolysin-deficient Strain of Bacillus subtilis
More LessAn autolysin-deficient mutant of Bacillus subtilis was completely tolerant to 5 h incubation with 50–100 µg cycloserine ml−1whereas the wild-type was rapidly lysed and killed by 12 µg ml−1. Lysis also did not occur when low concentrations of β-lactams were added to exponentially growing cultures of the mutant, but over 90% of the bacteria were killed within 90-120 min. Protein, lipid and peptidoglycan synthesis as well as growth were inhibited after about 60 min. At this time, but not earlier, small amounts of these three cell components appeared in culture supernatants. Earlier, at about 20-30 min, the intracellular pools of amino acids started to decline rapidly and there was a temporary apparent increase in the rate of lipid synthesis. Neither of the latter phenomena occurred with cycloserine, with which protein and lipid synthesis declined only slowly and the rate of peptidoglycan synthesis was 80% inhibited within 30 min. Only occasional cells with damaged walls were seen 30–90 min after addition of either β-lactams or cycloserine to the cultures. It thus seems unlikely that wall hydrolysis or penetration by residual autolysins in the mutant are responsible for mass cell death caused by the β-lactams.
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Mechanism Of Phage-Induced Lysis In Pneumococci
More LessEarlier studies have suggested the possible role of host autolytic enzyme in the release of progeny phage from Dp-1 infected pneumococci. Several new experiments described here reinforce this notion. Specifically, the resistance of an autolysis-defective mutant to infection at low phage to cell ratios could be eliminated by prior ‘coating’ of the host bacteria with pneumococcal autolysin isolated from wild-type cells. Similar, productive infection was also possible by lowering the temperature of incubation to 30 °C, a condition that leads to a partial activation of the thermosensitive residual autolysin in the mutant cells. Other experiments, however, clearly indicate the role of the newly discovered phage-associated lysin (PAL), reported in the accompanying communication, in bacteriophage release and culture lysis; specifically, lysis was stimulated by reducing agents and inhibited by cardiolipin. It seems that both the host-related and the PAL activities are involved with Dp-1 induced lysis of pneumococci.
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A Phage-associated Murein Hydrolase in Streptococcus pneumoniae Infected with Bacteriophage Dp-1
More LessA phage-associated murein hydrolase activity capable of degrading pneumococcal cell walls was isolated and purified to homogeneity from the phage-induced lysate of an autolysis-defective pneumococcal mutant infected with the bacteriophage Dp-1. Some properties of the enzyme resembled those of the wild-type (host) pneumococcal murein hydrolase: cell walls prepared from ethanolamine-grown pneumococci were resistant to the enzyme; the activity was inhibited by the Forssman antigen and was sensitive to proteolytic enzymes. The phage-associated enzyme was not inhibited by antiserum prepared against the purified pneumococcal murein hydrolase; the activity was stimulated by reducing agents and was partially inhibited by cardiolipin. The subunit molecular weight of the phage-associated enzyme was somewhat smaller (31000) than that of the pneumococcal hydrolase (35000). This appears to be the first description of a phage-associated murein hydrolase activity in pneumococci.
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Hydroxystreptomycin Production and Resistance in Streptomyces glaucescens
More LessThe wild-type strain of Streptomyces glaucescens produces hydroxystreptomycin and shows an inherent natural resistance to streptomycin group aminoglycoside antibiotics. Cell free extracts of the wild-type strain were able to inactivate streptomycin, hydroxystreptomycin and dihydrostreptomycin in the presence of ATP. The phosphotransferase did not inactivate other aminoglycoside antibiotics, including spectinomycin.
Mutant strains were isolated, which were highly sensitive to streptomycin group aminoglycosides, had no measurable phosphotransferase activity and were unable to form detectable amounts of hydroxystreptomycin. This suggests either a correlation between phosphotransferase activity, streptomycin resistance and hydroxystreptomycin formation or defects in more than one gene in the strS mutant strains tested.
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- Development And Structure
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Gas Vacuole Formation in Hormogonia of Nostoc muscorum
More LessGas vacuole formation was induced in a strain of Nostoc muscorum when the culture medium was diluted with water. The induction also occurred when a single ingredient of the culture medium, NaNO3, was withdrawn. Replacing this ingredient with one of a number of salts (NaCl, KCl, KNO3) in equiosmolar concentration prevented the induction, but replacing it with glucose or sucrose did not. Increased light intensity also induced gas vacuole formation. The combination of withdrawing NaNO3 and increasing light intensity gave a larger induction than the sum of each separately. Gas vacuoles disappeared about 3 d after formation. Their disappearance was accelerated by addition of chloramphenicol which led to collapse of the constitutive gas vesicles by rising cell turgor pressure. The induction of gas vesicles was accompanied by a number of other morphological changes representing the differentiation of hormogonia. Analysis of the cell protein extracts by polyacrylamide gel electrophoresis showed that de novo synthesis of the gas vesicle protein occurred during gas vacuole induction. A number of other proteins were also formed while others disappeared.
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Isolation And Properties Of Dictyostelium Discoideum Mutants Temperature-Sensitive For Spore Germination
More LessA new class of temperature-sensitive mutants defective in spore germination (termed spg) was isolated and characterized. The mutants germinate normally at 19 °C but are defective at 27 °C. Analysis of the germination of these mutants at the non-permissive temperature after periods of incubation at 19 °C shows that the temperature-sensitive step in germination occurs somewhere between 60 and 120 min at 19 °C. Activated mutant spores can be deactivated by incubation at 27 °C prior to shift to the permissive temperature. The mutants are not temperature-sensitive for growth or development.
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Isolation And Characterization Of The Outer And Cytoplasmic Membranes Of Pseudomonas cepacia
More LessA method is described for the separation of the outer membrane (OM) from the cytoplasmic membrane (CM) of Pseudomonas cepacia grown in nutrient broth and in chemically defined media under different nutrient depletions. The method is particularly valuable since it is effective when applied to stationary phase cells. Enzyme activities indicated that the contamination of the OM with the CM was less than 5%. The OM protein profile of magnesium-depleted cells was much simpler than that of the iron-depleted and nutrient broth grown cells. The apparent molecular weights of the OM proteins of magnesium-depleted cells were: 40000, 36000, 24500 and 14500. Iron depletion induced the synthesis of an OM protein with apparent molecular weight of 66000. The OM proteins with apparent molecular weights of 40000, 36000 and 24500 were heat-modifiable and the 24500 dalton protein was found also to be affected by the presence of 2-mercaptoethanol. The OM consisted of 50% protein and 20% phospholipid and the rest was probably LPS while the CM consisted of 80% phospholipid and 20% protein. The major phospholipid in both membranes was phosphatidylethanolamine with a smaller amount of phosphatidylglycerol and a trace amount of phosphatidylcholine; the OM contained more phosphatidylethanolamine than the CM.
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- Ecology
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Root Residues: Substrates Used By Fusarium Culmorum To Infect Wheat, Barley And Ryegrass
More LessFusarium culmorum was grown on different natural substrates and its subsequent pathogenicity towards wheat, barley and ryegrass studied. This fungus caused more inhibition of plant growth of all test species when grown on root residues than when present as a spore suspension in sand. More wheat seedlings were killed when sown into infected ryegrass root residues than when sown into infected wheat or barley residues. However, when ryegrass was sown into infected ryegrass roots no plant death occurred compared with over 50% when sown into infected wheat or barley. Dressing ryegrass seeds with a formulation containing calcium peroxide gave some control of F. culmorum. These results are discussed in relation to the problems that can sometimes occur following reseeding of grassland.
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- Genetics And Molecular Biology
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Spovh and SpoVJ - New Sporulation Loci In Bacillus Subtilis 168
More LessThree sporulation mutants have been isolated which produce spores with an atypical resistance phenotype, i.e. they are sensitive to organic solvents and heat but resistant to lysozyme. All three mutants produced serine protease, alkaline phosphatase and glucose dehydrogenase which are biochemical marker events for stages I, II and III. Two of the three mutants produced dipicolinic acid, a late marker, but the third was defective in its production. Heat-resistance was not restored to any of the mutants by the provision of exogenous dipicolinate. Gel electrophoresis showed that the mutant spores had similar patterns of spore coat proteins to the wild-type and electron microscopy revealed no significant structural differences. The three mutations responsible for the phenotypes of the mutant spores lie in the phe-argA region of the Bacillus subtilis chromosome. Recombination index values indicate that the mutations are in three separate genes. They define at least two new sporulation loci, designated spoVH and spoVJ.
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The Isolation Of λ Transducing Phages Carrying the citG and gerA Genes Of Bacillus Subtilis
More LessSUMMARY: λgt WES derivatives carrying the citG (fumarase) gene of Bacillus subtilis have been detected by complementation of an Escherichia coli fumarase mutation in lysogen-filled plaques. The gerA gene, mutations in which affect the germination response of spores to l-alanine, is also present on the two citG transducing phages described. The cloned regions in these two phages include EcoRI-generated fragments of 5·0 kb and 1·4 kb; the former fragment carries citG4 +.
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Transduction of Escherichia coli trp Genes in Salmonella typhimurium and Effect of N-Methyl-N′-Nitro-N-Nitrosoguanidine on Transduction with Heterogenotic DNA
More LessSUMMARY: P1Kc-mediated transduction of Escherichia coli trp genes occurred at a frequency of about 10−8 in Salmonella typhimurium trp strains carrying mutations determining sensitivity to P1 and a low level of restriction enzymes. Heterospecific transductants were analysed by using them as donors in second-stage transductions mediated by bacteriophage KB int. One class of heterospecific transductants had the phenotype Trp+ Pro− but were extremely unstable and reverted at high frequency (up to 80%) to the parental phenotype. The Trp+ Pro− phenotype probably represents insertions of the E. coli trp genes in the S. typhimurium pro genes. It was stable in a RecA background.
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Phosphotransferase-Mediated Regulation Of Carbohydrate Utilization In Escherichia coli K12: the Nature of the iex (crr) and gsr (tgs) Mutations
More LessMutants of Escherichia coli K12 defective in the gene iex (crr) no longer utilize glucose or N-acetylglucosamine in preference to lactose, but competition between either of these sugars and another that also enters by a phosphotransferase (PT) mechanism is not affected. In this they differ from gsr (tgs) mutants. In gsr mutants, glucose does not exclude any other sugar, though N-acetylglucosamine still does so. In gsr mutants that are also ptsM the phosphoenolpyruvate-dependent phosphorylation of glucose or methyl α-glucoside is reduced by 90%: N-acetylglucosamine phosphorylation is not affected. The iex mutation does not affect the phosphorylation of either of these compounds. The wild-type alleles iex + and gsr + are dominant in λ heterozygotes. Glucose inhibits the lactose permease of wild-type cells, but only when the permease is present in low amounts. The inhibition is also relieved (1) by induction of another transport system that is subject to regulation by the iex system or (2) by an iex mutation. We suggest that the iex gene specifies a protein that, in cells transporting certain sugars by a PT mechanism, acts to inhibit active transport systems. The protein is present in limiting concentration in the cell, sufficient only to inhibit the basal, uninduced, level of the active transport systems. In consequence the inducer (or its precursor) may be excluded from the cell and induction thus prevented.
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Phosphotransferase-Mediated Regulation Of Carbohydrate Utilization In Escherichia coli K12: Location of the gsr (tgs) and iex (err) Genes by Specialized Transduction: With an Appendix: Two Separate Genes Involved in Sulphate Transport in Escherichia coli K12
More LessA lysogen of Escherichia coli K12 with λ cI857 S7 xis6 nin5 b515 b519 integrated into ptsI was induced and the lysates plated on a Pel− host [on which λ strains with less than the wild-type amount of DNA form plaques at low frequency ( Cameron et al., 1977 )]. All of the 40 plaques examined contained phage able to transduce at least two of the genes known from bacteriophage P1 transduction experiments to be closely linked to ptsI. Assuming that each specialized transducing phage arose by a single illegitimate recombination event, the distribution of phage types showed that the gene order is cysA gsr ptsI (ptsH, iex) cysZ lig; both gsr + and iex + were dominant. Analysis of restriction endonuclease digests of the transducing phage confirmed that no unexpected DNA rearrangements had taken place and allowed the construction of a map of the sites of action of the restriction endonucleases EcoRI, HindIII, BamI and Kpn for over 20 kilobases of E. coli DNA.
In an Appendix, we show cysA and cysZ mutants to be deficient in sulphate assimilation.
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Release Of High Molecular Weight Dna From Neurospora Crassa Using Enzymic Digestions
More LessMethods are described that allow extraction of high molecular weight DNA from germinated conidia of Neurospora crassa. By labelling DNA with ribonucleosides, early conidia were shown to be active in DNA synthesis. These cells when treated with the enzyme Zymolyase became fragile and could be readily lysed with ionic detergents to release high molecular weight DNA.
The DNA extracted from Zymolyase treated cells on to alkaline sucrose gradients sedimented as a heterogeneous species of up to 150 ×106 molecular weight. A minor DNA species (presumably mitochondrial) of 20×106 molecular weight comprised 2-7% of the total. The identity of the DNA was confirmed by sensitivity to DNAase, the diphenylamine assay and TLC. Sedimentation patterns were unaffected by protease digestions and no anomalous high speed rotor effects were evident. Isopycnic gradients suggested that the DNA released was uncomplexed with either protein or carbohydrates. Sepharose chromatography of extracted, RNAase-treated Zymolyase lysate resulted in clearly separate high molecular weight DNA and RNA-protein elution profiles.
UV light preferentially inhibited nuclear DNA synthesis and drastically reduced the size and amount of nascent DNA being synthesized in the excision defective uvs-2 mutant. Sites in parental DNA sensitive to Micrococous luteus UV endonuclease were measured in cells made permeable with Triton X-100.
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Chromosomal Instability in Streptomyces glaucescens: Mapping of Streptomycin-sensitive Mutants
More LessStreptomyces glaucescens strain GLA0 (= ETH 22794) produces hydroxystreptomycin and has a high natural resistance to hydroxystreptomycin, dihydrostreptomycin and streptomycin. The wild-type strain gives rise spontaneously to streptomycin-sensitive (StrS−) variants at a frequency of 0.2 to 1.4%. These mutants lack streptomycin phosphotransferase activity responsible for the wild-type resistance to streptomycin group antibiotics and are unable to produce detectable amounts of hydroxystreptomycin.
Mapping experiments showed that the strS marker lies between the chromosomal markers lys-2 and ura-3 on the linkage map of S. glaucescens. The molecular basis for instability of this marker is as yet unknown.
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- Immunology
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Immunological Relationship Between The Capsular Polysaccharides Of Neisseria Meningitidis Serogroups Z and 29E
More LessThe immunological relationship between serogroups 29E and Z of Neisseria meningitidis was investigated using bacterial agglutination, precipitin-in-gel, primary antigen binding and immune lysis assays. The two capsular polysaccharides were both cross immunogenic and cross reactive. Demonstration of the relationship using group Z antisera depended on which assay was used. It was most readily apparent in assays of immune lysis, less apparent when precipitins were sought in gel and inapparent when bacterial agglutination, the standard assay for determining serogroup, was employed. The cross reacting epitope was expressed 10-fold more within the group 29E polysaccharide than within the group Z polysaccharide. These findings imply that inclusion of either polysaccharide in a polyvalent meningococcal vaccine may obviate the need to include the other polysaccharide.
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- Pathogenicity And Medical Microbiology
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Growth Of Tyzzer’s Organism in Primary Monolayer Cultures of Adult Mouse Hepatocytes
More LessThe Tyzzer’s disease organism was grown in primary monolayer cultures of adult mouse hepatocytes prepared by collagenase perfusion. The organisms produced a plaque-like cytopathic effect involving almost the whole culture around 72 h post-infection when the bacterial growth reached a maximum. The organisms showed specific immunofluorescence, and electron microscopy revealed that intracellular organisms had peritrichous flagella and underwent cell division. After intravenous inoculation of the infected cell culture into mice, necrotic hepatitis was produced and the organisms, recovered from the liver lesion, could be propagated in primary culture of mouse hepatocytes.
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Virulence For Mice Of A Proteinase-Secreting Strain Of Candida Albicans and A Proteinase-Deficient Mutant
More LessA proteinase-deficient mutant of Candida albicans, M12, was produced by nitrosoguanidine mutagenesis of a proteinase-producing strain, ATCC 28366. The mutant was phenotypically identical to its parent in nearly all biochemical and morphological characteristics except proteinase production. The mutant was considerably less lethal than the parent when inoculated intravenously into mice and lower counts of C. albicans were recovered from the organs of mice infected with the mutant. Both strains were phagocytosed and killed to a similar extent by human and murine polymorphonuclear leukocytes when the yeasts were grown in a medium that did not induce proteinase production. However, in a proteinase-inducing medium, ATCC 28366 was phagocytosed and killed less well than M12. These results indicate that proteinase secretion by C. albicans is one factor determining the virulence of the species, but that other virulence factors are also involved in the pathogenesis of systemic candidosis.
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Insect Pathogenic Properties Of Serratia Marcescens. Passive And Active Resistance To Insect Immunity Studied With Protease-deficient And Phage-Resistant Mutants
More LessMany insects have a cell-free immune system in which small basic proteins called cecropins are the main defence against Gram-negative bacteria. We have earlier shown that an insect pathogenic strain of Serratia marcescens was resistant to insect immunity and that certain mutants resistant to phage ɸJ become sensitive to cecropins. We have found that protease-deficient mutants with and without resistance to ɸJ appear to be deficient in the mechanism of protease induction. Three different protease fractions exist and for two of the enzymes we describe a partial purification and characterization. The proteases show pronounced autodegradation which increases with the purity. Both enzymes are only partly affected by EDTA and they are highly toxic to Drosophila melanogaster. All three enzymes destroy cecropins in immune haemolymph from Cecropia pupae. However, in vivo experiments with different mutants indicate that in Serratia, passive resistance to insect immunity is more important for virulence in Drosophila than the production of proteases which can destroy cecropins.
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- Physiology And Growth
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A Minimal Medium For The Cultivation Of Infective Trypanosoma Cruzi Epimastigotes
More LessSUMMARY: In a culture medium containing bovine liver catalase, but lacking exogenous free amino acids, only two vitamins (choline and folic acid) were found to be essential for the continuous in vitro multiplication of seven different infective strains of Trypanosoma cruzi. The provision of additional vitamins or sugars had no stimulatory effect under these culture conditions. These, and previous studies, have allowed the design of a trypanosomal minimal medium composed only of bovine liver catalase, choline, folic acid, glucose and inorganic salts. This was able to support the continuous cultivation of T. cruzi for more than 12 consecutive passages (i.e. about 160 d of culture). By several criteria, namely morphological features as seen by electron microscopy, infectivity for vertebrate and invertebrate hosts, glucose utilization and protein biosynthesis, this medium (which is the simplest so far described) proved to be nutritionally adequate for Trypanosoma spp. In addition, the medium appeared to be relatively specific for T. cruzi, as it did not support the growth of T. rangeli and American isolates of leishmania.
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Growth Defects Of Escherichia Coli Cells Which Contain The Gene Of An α-Amylase from Bacillus coagulans on a Multicopy Plasmid
More LessAn α-amylase gene from Bacillus coagulans has previously been cloned in Escherichia coli and shown to direct the synthesis of an enzymically active protein of 60000 Dal ( Cornelis et al., 1982 ). In one particular E. coli host, strain HB101, amylase was found to accumulate in the periplasmic space. To study the processing and the location of the amylase, plasmid pAMY2 was introduced into E. coli 188 which is a strain constitutive for alkaline phosphatase, a periplasmic marker, and for β-galactosidase, a cytoplasmic marker. Abnormally large amounts of both a-amylase and β-galactosidase were found in the culture fluid of cells grown in rich medium. Furthermore a severe growth defect was found when cells containing pAMY2 were grown in maltose and glycerol media, while the ability to grow on glucose remained normal. This defect could be reversed by two types of spontaneous mutations. Mutations in the first class are located on the plasmid and correspond to the insertional inactivation of the amylase gene by IS1. Mutations in the second class are located on the host chromosome. These results suggest that the synthesis and export of B. coagulans α-amylase is deleterious to E. coli, especially in media containing maltose or glycerol as sole carbon source.
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Catabolite Effects On Enzyme Induction And Substrate Utilization In Rhizobium leguminosarum
More LessThe catabolism of l-histidine and p-hydroxybenzoate in Rhizobium leguminosarum 3841 is inducible. Glucose or succinate have relatively little effect on the induction of histidase whereas they produce about 50% repression of the p-hydroxybenzoate catabolic system. When grown in the presence of a mixture of carbon sources, e.g. glucose plus histidine, or succinate plus p-hydroxybenzoate, the cells co-utilize both substrates. However, consumption of histidine and p-hydroxybenzoate (which support slower growth rates than glucose or succinate) is substantially reduced in comparison with that of glucose or succinate.
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The Interrelation Of Phototaxis, Membrane Potential And K+/Na+ Gradient In Halobacterium Halobium
More LessThe attractant effect of green light and the repellent effect of blue light on Halobacterium halobium were studied. It was found that addition of CN− and dicyclohexylcarbodiimide, which block the redox chain and H+-ATPase, respectively, increased both the amplitude of light-dependent changes of membrane potential (∆ψ), monitored by the distribution of tetraphenyl-phosphonium, and the sensitivity of the green-light taxis. A direct proportionality between ∆ψ and the green-light sensitivity was revealed. The sensitivity of the green-light taxis was decreased by glucose, histidine and Na+/K+ gradient, i.e. factors reducing the light-dependent changes of protonic potential. These factors did not affect the blue-light taxis. The uncoupler carbonyl cyanide m-chlorophenylhydrazone appears to repel H. halobium cells. These data are in agreement with the assumption that the green-light taxis is governed by a sensing of protonic potential, whereas the blue-light taxis is mediated by a specific photoreceptor.
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The Influence Of Ionic Strength, Ph And A Protein Layer On The Interaction between Streptococcus Mutans And Glass Surfaces
More LessThe initial interaction between Streptococcus mutans and hard surfaces has been investigated using a rotating disc technique. The deposition to clean and BSA-coated glass of two strains of S. mutans, FA-1 (serotype b) and KPSK2 (serotype c), which exhibit different surface properties, was studied. Organisms were harvested from cultures grown in a chemostat at a dilution rate of 0·06 h−1 and suspended in NaCl solutions of defined ionic strengths and pH values. The deposition of both strains showed a strong dependence on electrolyte concentration, particularly at low ionic strengths, which was inversely related to the zeta potentials of the organisms. Similarly, the ionic strength at which maximum deposition was first noted (critical coagulation concentration) for the two strains correlated with their relative potentials. Deposition was insensitive to changes in pH at an electrolyte concentration of 0·05 m. The maximum observed deposition did not approach values predicted by theory, suggesting that a further barrier to deposition, other than electrostatic repulsion, might exist. Under all experimental conditions, some of the deposited bacteria were observed to be oscillating, suggesting that they were held at a distance from the collector surface. The cells did not, however, appear to be deposited in a secondary minimum predicted by DLVO theory hence it may be that long-range polymer interactions are also involved in the deposition of these organisms.
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Alteration Of Susceptibility To Edta, Polymyxin B And Gentamicin In Pseudomonas Aeruginosa By Divalent Cation Regulation Of Outer Membrane Protein H1
More LessInduction of outer membrane protein H1 in Pseudomonas aeruginosa results in decreased susceptibility to aminoglycosides, polymyxin B, and EDTA. We have previously shown that protein H1 can become the major cellular protein in cells grown in low (0·02 mm) Mg2+. The induction of protein H1 was prevented by supplementation of low Mg2+ medium with Mg2+, Ca2+, Mn2+, or Sr2+ (each at 0·5 mm), but not with Zn2+, Ba2+, Sn2+, Al3+ or Na+ (each at 0·5 mm). Only cells grown in the presence of those cations which failed to prevent H1 induction were resistant to the cationic antibiotics, polymyxin B and gentamicin, and to chelators of divalent cations. Cells grown in Ca2+, but not in Mg2+, were susceptible to outer membrane permeabilization by the Ca2+ specific chelator EGTA, whereas both were susceptible to EDTA. In agreement with this, cells grown in Mg2+, Ca2+, Mn2+, or Zn2+ showed enhanced levels of these cations respectively as their major cell envelope-associated cation. When cells were shifted from low to high Mg2+ medium, the time course of the decrease in the levels of protein H1 correlated well with the increase in sensitivity to EDTA and polymyxin B. These results support the hypothesis that protein H1 acts to replace divalent cations at a critical outer membrane site attacked by cationic antibiotics and chelators of divalent cations, and suggest that only a small proportion of the total divalent cation-binding sites in the outer membrane are susceptible to attack by these agents.
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- Short Communication
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A Conditional Aerial Mycelium-Negative Mutant Of Streptomyces Fradiae with Deficient Ornithine Carbamoyltransferase Activity
More LessA mutant defective in ornithine carbamoyltransferase activity and having a concomitant aerial mycelium-negative phenotype was isolated from Streptomyces fradiae. The aerial mycelium formation of the mutant could be restored by replacing l-arginine with l-citrulline in the minimal medium. The possibility that the ornithine cycle is connected with the regulation of aerial mycelium formation is discussed.
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- Taxonomy
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Numerical Analysis Of Total Fatty Acid Profiles In The Identification Of Coryneform, Nocardioform And Some Other Bacteria
More LessFatty acid profiles of 202 coryneform and nocardioform bacteria were recorded by gas chromatography. Strains were grouped according to their profiles using mean linkage cluster analysis and similarity measures based on the correlation coefficient, the angular separation between vectors in a multidimensional space and the degree of overlap between superimposed traces. Comparisons using both real and hypothetical data showed the last of these measures to be the most effective. Strains were divided into two major groups, depending on whether they contained predominantly straight chain or iso- and anteiso-branched acids. The first group was divided into two subgroups according to the relative proportions of the characteristic acids present; one subgroup had six clusters containing the rhodococci, nocardiae, mycobacteria and caseobacters, and the other had two containing the xanthobacters and true corynebacteria. The second group was divided into one subgroup containing strains of Arthrobacter simplex, Arthrobacter tumescens and Arthrobacter duodecadis, and one having three clusters. One cluster from this latter subgroup contained cellulomonads, one contained brevibacteria and curtobacteria and one contained arthrobacters, oerskoviae and kurthiae. Identification to generic level by fatty acid composition alone may not be feasible, but fatty acid analysis coupled with morphological examination may be sufficient to identify Corynebacterium, Arthrobacter, Cellulomonas, Oerskovia, Brevibacterium, Caseobacter, Kurthia and the A. simplex/tumescens taxon. Distinction is not easy between Curtobacterium, Microbacterium and the diaminobutyric acid-containing coryneforms and between Rhodococcus, Mycobacterium and Nocardia.
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Aminopeptidase Activity Of Leptospira Strains
More LessA total of 15 cultures of Leptospira were examined for aminopeptidase activity using 22 aminoacyl-β-naphthylamide substrates. Activity was demonstrated in each of the cultures. Extracts from serovars of Leptospira interrogans preferentially hydrolysed the same range of substrates. The level of hydrolysis of the preferred substrates for the seven strains of L. interrogans was distinctively higher than that demonstrated for the six Leptospira biflexa strains. Extracts from cultures of Leptospira illini and Leptospira parva sp. nov. exhibited profiles different to those demonstrated for the other 13 leptospiral cultures examined.
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Determination Of Fatty Acids And Carbohydrate Monomers In Micro-Organisms By Means Of Glass Capillary Gas Chromatography: Analysis Of Mycobacterium gordonae and Mycobacterium scrofulaceum
Trifluoroacetylated whole-cell methanolysates of four strains each of Mycobacterium gordonae and Mycobacterium scrofulaceum were analysed by gas chromatography, using a glass capillary column. The major chromatographic peaks were identified by mass spectrometry as derivatives of fatty acids and carbohydrates. In addition, two predominant peaks, present in chromatograms representing M. scrofulaceum, were identified as 2-octadecanol and 2-eicosanol. These secondary alcohols were not found in any of the strains of M. gordonae studied. The amount of tuberculostearic acid in the latter species was less than 1 % of that in M. scrofulaceum.
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Volume 121 (1980)
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Volume 120 (1980)
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Volume 119 (1980)
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Volume 118 (1980)
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Volume 117 (1980)
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Volume 116 (1980)
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Volume 115 (1979)
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Volume 114 (1979)
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Volume 113 (1979)
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Volume 112 (1979)
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Volume 111 (1979)
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Volume 110 (1979)
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Volume 109 (1978)
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Volume 108 (1978)
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Volume 107 (1978)
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Volume 106 (1978)
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Volume 105 (1978)
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Volume 104 (1978)
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Volume 103 (1977)
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Volume 102 (1977)
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Volume 101 (1977)
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Volume 100 (1977)
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Volume 99 (1977)
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Volume 98 (1977)
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Volume 97 (1976)
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Volume 96 (1976)
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Volume 95 (1976)
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Volume 94 (1976)
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Volume 93 (1976)
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Volume 92 (1976)
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Volume 91 (1975)
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Volume 90 (1975)
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Volume 89 (1975)
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Volume 88 (1975)
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Volume 87 (1975)
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Volume 86 (1975)
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Volume 85 (1974)
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Volume 84 (1974)
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Volume 83 (1974)
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Volume 82 (1974)
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Volume 81 (1974)
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Volume 80 (1974)
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Volume 79 (1973)
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Volume 78 (1973)
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Volume 77 (1973)
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Volume 76 (1973)
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Volume 75 (1973)
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Volume 74 (1973)
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Volume 73 (1972)
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Volume 72 (1972)
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Volume 71 (1972)
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Volume 70 (1972)
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Volume 69 (1971)
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Volume 68 (1971)
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Volume 67 (1971)
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Volume 66 (1971)
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Volume 65 (1971)
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Volume 64 (1970)
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Volume 63 (1970)
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Volume 62 (1970)
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Volume 61 (1970)
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Volume 60 (1970)
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Volume 59 (1969)
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Volume 58 (1969)
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Volume 57 (1969)
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Volume 56 (1969)
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Volume 55 (1969)
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Volume 54 (1968)
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Volume 53 (1968)
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Volume 52 (1968)
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Volume 51 (1968)
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Volume 50 (1968)
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Volume 49 (1967)
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Volume 48 (1967)
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Volume 47 (1967)
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Volume 46 (1967)
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Volume 45 (1966)
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Volume 44 (1966)
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Volume 43 (1966)
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Volume 42 (1966)
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Volume 41 (1965)
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Volume 40 (1965)
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Volume 39 (1965)
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Volume 38 (1965)
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Volume 37 (1964)
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Volume 36 (1964)
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Volume 35 (1964)
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Volume 34 (1964)
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Volume 33 (1963)
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Volume 32 (1963)
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Volume 31 (1963)
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Volume 30 (1963)
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Volume 29 (1962)
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Volume 28 (1962)
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Volume 27 (1962)
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Volume 26 (1961)
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Volume 25 (1961)
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Volume 24 (1961)
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Volume 23 (1960)
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Volume 22 (1960)
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Volume 21 (1959)
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Volume 20 (1959)
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Volume 19 (1958)
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Volume 18 (1958)
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Volume 17 (1957)
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Volume 16 (1957)
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Volume 15 (1956)
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Volume 14 (1956)
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Volume 13 (1955)
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Volume 12 (1955)
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Volume 11 (1954)
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Volume 10 (1954)
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Volume 9 (1953)
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Volume 8 (1953)
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Volume 7 (1952)
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Volume 6 (1952)
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Volume 5 (1951)
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Volume 4 (1950)
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Volume 3 (1949)
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Volume 2 (1948)
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Volume 1 (1947)