- Volume 118, Issue 1, 1980
Volume 118, Issue 1, 1980
- Biochemistry
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Metabolism of Di(ethylene glycol) [2-(2′-Hydroxyethoxy)ethanol] and Other Short Poly(ethylene glycol)s by Gram-negative Bacteria
More LessObligately aerobic Gram-negative rod-shaped bacteria isolated from soil, sewage and river water grew using ethan-1,2-diol (MEG), 2-(2′-hydroxyethoxy)ethanol (DEG) or poly(ethylene glycol)s of up to 1500 molecular weight as sole carbon and energy source, though no single strain used the whole range. Only organisms that grew using MEG could grow on glycine or glycollate. An Acinetobacter strain (S8) degraded DEG and short poly(ethylene glycol)s by non-oxidative removal of ethylene oxide units as acetaldehyde, using a membrane-bound oxygen-sensitive enzyme of a novel type - DEG lyase - and leaving an unusable MEG residue. The C2 units could be used for energy generation by the tricarboxylic acid cycle and for anabolic and anaplerotic functions via the glyoxylate cycle, key enzymes of which were induced by growth of the bacteria on DEG or short poly(ethylene glycol)s.
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Purification and Partial Characterization of an Acid Phosphatase (EC 3.1.3.2) Produced by Propionibacterium acnes
More LessA strain of Propionibacterium acnes (type I; Marples & McGinley, 1974 ), isolated from a blackhead acne lesion, produced an acid phosphatase which was present in the culture supernatant in the late-exponential and early-stationary phases of growth. This acid phosphatase was purified more than 45000-fold (4·5% yield). The purified enzyme gave two protein bands on sodium dodecyl sulphate-polyacrylamide gel electrophoresis corresponding to molecular weights of 155000 and 87100. The enzyme had a single peak of activity on Sephadex G-100, with a molecular weight corresponding to 93000. The highly purified acid phosphatase had an optimum activity at pH 5·8, was stable from pH 4·0 to 5·5 and was totally inactivated after 30 min at 55 °C. The enzyme did not show an absolute requirement for metal ions, but was stimulated by Mg2+, Ca2+, Zn2+ and K+ at concentrations between 0·1 and 1 mm. The acid phosphatase was active against a number of monophosphate esters.
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Characterization of an Extracellular α-Amylase from Bacillus megaterium sensu stricto
More LessBacillus megaterium sensu stricto (NCIB 7581) produced amylase throughout exponential growth and during the early-stationary phase. Enzyme synthesis occurred in the absence of α-glucans but the yield was maximal when malt extract or starch was supplied as carbon source. Of the nitrogen sources examined, soya flour stimulated the highest yield of amylase. The enzyme was susceptible to reagents that react with thiol groups and had an exo-action on starch yielding maltose with a β-anomeric configuration. It is concluded that the principal starch-hydrolysing enzyme from B. megaterium NCIB 7581 is a (1→4)-α-d-glucan maltohydrolase similar in its properties to other Bacillus and plant β-amylases.
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The Lipid Fatty Acids of Proteolytic Clostridia
More LessCapillary gas-liquid chromatography (g.l.c.) and g.l.c./mass spectrometry (g.l.c./m.s.) were used to study the fatty acid composition of the lipids of the following 23 species of proteolytic clostridia grown in a Trypticase/yeast extract medium: Clostridium bifermentans, C. cadaveris, C. caloritolerans, C. cochlearium, C. difficile, C. ghoni, C. glycolicum, C. histolyticum, C. lentoputrescens, C. limosum, C. lituseburense, C. malenominatum, C. mangenotii, C. propionicum, C. putrefaciens, C. putrificum, C. scatologenes, C. sordellii, C. sporogenes, C. sticklandii, C. subterminale, C. tetani, C. tetanomorphum. These species contained a total of 55 fatty acids in the range C12 to C18. The methyl esters were separated on a 152 m stainless steel capillary column coated with poly(l,4-butanediol succinate) and characterized by their equivalent chain lengths and by g.l.c./m.s. The predominant acids were n-C14;0 and n-C16:0. There were two groups of organisms: those which contained fatty acids of the n, iso and anteiso series and those which contained only those of the n series. All the organisms which contained iso and anteiso acids also oxidized valine, leucine and isoleucine to the corresponding branched-chain volatile fatty acids. The iso acids found had both even and odd numbers of carbon atoms and were probably derived from valine and leucine, respectively; the anteiso acids all had odd numbers of carbon atoms and were probably derived from isoleucine via 2-methylbutyric acid. These organisms also produced small amounts of monoenoic iso acids. Of the seven species which contained only acids of the n series, C. histolyticum produces acetic acid as its only end-product whereas the other six ferment glutamic acid and produce acetic and n-butyric acids; they also form propionic acid from threonine.
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The Siderochromes of Non-fluorescent Pseudomonads: Production of Nocardamine by Pseudomonas stutzeri
More LessWhen Pseudomonas stutzeri was grown in iron-deficient conditions it excreted a colourless compound which was identified as nocardamine, a trihydroxamate, which is produced in similar conditions by actinomycetes. The production of this compound (which is related to the ferric iron content of the culture medium), as well as its ability to form very stable Fe(III) complexes, suggest that it is a desferri-siderophore.
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Anaerobic Glucose and Serine Metabolism in Staphylococcus epidermidis
More LessAnaerobically grown Staphylococcus epidermidis fermented glucose with the production of lactate and trace amounts of acetate, formate and CO2. Isotopic and inhibitor studies, assays for key enzymes of different metabolic pathways, and fermentation balances, all indicated that glucose was metabolized principally via glycolysis and to a very limited extent by the hexose monophosphate oxidative pathway. Serine fermentation proceeded via deamination and dismutation yielding NH3 and equimolar amounts of lactate, acetate and CO2; small amounts of formate arose by the operation of pyruvate-formate lyase. Incorporation of 0·5% (w/v) glucose in the growth medium depressed serine metabolism by repressing the activities of serine dehydratase and pyruvate dehydrogenase but, conversely, enhanced the activities of phosphofructokinase and lactate dehydrogenase. Glucose-grown organisms at various stages of anaerobic batch growth showed an inverse relationship between the rates of fermentation of serine and glucose. l-Lactate dehydrogenase activity in crude extracts depended on fructose 1,6-bisphosphate, and fructose 1,6-bisphosphate aldolase was found to be a class I aldolase. Despite the presence of ribokinase, d-ribose-5- phosphate isomerase, transaldolase and transketolase, the organisms utilized ribose only after growth aerobically in basal medium, and then at a slow rate after an initial lag period.
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The Microbial Metabolism of Acetone
More LessFour Gram-positive bacteria have been isolated from separate soil samples by enrichment culture with acetone as sole source of carbon. Whole cells of all strains grown on acetone rapidly oxidized acetone, acetol and methylglyoxal, and three of the four also oxidized isopropanol. The patterns of induced enzymes in cell extracts are compatible with the oxidation sequence: isopropanol → acetone → acetol → methylglyoxal → pyruvate. Although an enzyme system capable of converting acetone into acetol has not been detected, the inclusion of acetol in the pathway is supported by the results of studies with whole cells and [14C]acetone. The proposed pathway of acetone metabolism is contrasted with evidence for an alternative, but not fully understood, pathway used by Mycobacterium vaccae JOB5.
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Cerulenin Inhibits Production of Extracellular Proteins but not Membrane Proteins in Bacillus amyloliquefaciens
More LessCerulenin inhibited the secretion of extracellular proteins by washed cell suspensions of Bacillus amyloliquefaciens. α-Amylase and protease secretion were inhibited by 80% and 75%, respectively, over 3 h. Cerulenin at 100 μg ml−1 inhibited incorporation of [1,2-14C]- acetate into intracellular lipid by about 75% without affecting cell growth, total protein synthesis or membrane protein synthesis. The inhibitory effect of cerulenin on α-amylase and protease secretion could be partially reversed if cell suspensions were supplemented with either fatty acids prepared from the lipids extracted from B. amyloliquefaciens or various individual pure fatty acids. Cerulenin significantly altered the ratio of lipid to protein in isolated membranes. However, this alteration was not affected by adding fatty acids which restored enzyme secretion. These results suggest that cerulenin may affect the availability of lipid directly concerned with the secretion process. The differential effect of cerulenin on the production of extracellular proteins and membrane proteins also suggests that the synthesis of these two classes of proteins occurs via mechanisms that differ.
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Purification and Properties of (1→3)-α-Glucanases from Bacillus circulans WL-12
More LessExtracellular endo-(1→3)-1-glucanase (EC 3.2.1.59) was optimally induced in Bacillus circulans WL-12 when grown in a mineral medium containing intact cells of Schizosaccharomyces pombe or extensively purified (1→3)-α-glucan as the carbon source. The enzyme activity was separated from most other proteins, including the β-glucanases, by affinity adsorption of the enzyme on water-insoluble colloidal (1→3)-α-glucan. The enzyme was released by allowing it to hydrolyse this substrate and purified further by DEAE-agarose chromatography and polyacrylamide P-150 gel filtration. Passage over DEAE-agarose apparently also separated a minor (1→3)-α-glucanase component. The principal (1→3)-α-glucanase was specific for the (1→3)-α-glucosidic bond and hydrolysed (1→3)-α-glucan endolytically to a mixture of nigerose and glucose with a transient accumulation of nigerotetraose. The reaction proceeded at a constantly declining rate with either colloidal (1→3)-α-glucan or with the soluble carboxymethyl-(1→3)-α-glucan as substrate. Nigeran, containing alternating (1→3)-α- and (1→4)-α-linkages, was not hydrolysed. Substrate dependence showed Michaelis-Menten kinetics. There was a pH optimum of 7·5 to 8·5 with a pronounced shoulder at pH 5 to 7. The molecular weight was estimated by slab gel electrophoresis in sodium dodecyl sulphate to be 134000. The enzyme did not appear to require divalent metal ions because its activity was stimulated by EDTA. There was evidence for essential thiol groups. Carbohydrate was not detected in the enzyme.
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- Development And Structure
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Elaboration of Both the Group W135 and Group Y Capsular Polysaccharides by a Single Strain of Neisseria meningitidis
More LessA single strain (8021) of Neisseria meningitidis, isolated from a child with disseminated meningococcal disease, was found to elaborate two serogroup-specific capsular polysaccharides - Y and W135. The original isolate as well as the progeny of ten single colony sub-isolates each agglutinated with both group Y and group W135 serogrouping antisera. The capsular polysaccharide of strain 8021 contained the chemical constituents of both the W135 and Y capsular polysaccharides in a ratio of about 2.5:1. The patient responded immunologically to both capsular polysaccharides with haemagglutinating antibodies. Analysis by double diffusion in agar revealed that the capsular polysaccharide of strain 8021 contained individual molecules of group W135 and group Y capsular polysaccharides as well as a mosaic molecule containing both antigenic determinants.
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Immunoelectron Microscopic Study of the Location of Group-Specific and Protein Type-Specific Antigens of Group B Streptococci
More LessThe ultrastructural location of the group-specific polysaccharide and the type-specific protein antigens R and X of group B streptococci was studied by means of the direct immunoferritin technique. The group-specific antigen was located on the outer wall layer. The specificity of the reaction was proved by the inhibition of labelling after absorption of the antibody-ferritin conjugate with group B polysaccharide. On the other hand, the demonstration of the polysaccharide was not sterically hindered by protein type antigens. As with group A and C streptococci the group polysaccharide could be localized on both the outer and inner surfaces of isolated walls. The protein antigens R and X were also demonstrated on the wall surface. The specificity of the reaction was ensured by making use of the enzymic sensitivity of these antigens. The location of the R protein on long filaments protruding from the cell surface resembles that of M protein of group A streptococci. In contrast to the group polysaccharide both the R and X protein antigens are localized only on the outer surface of isolated walls.
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Spore Outgrowth and the Development of Flagella in Bacillus subtilis
More LessMorphological aspects of the outgrowth of Bacillus subtilis strain w23 from heat-activated spores were examined by scanning electron microscopy. After 60 min incubation at 37 °C on agar medium, cracks appeared on the spore shells at their equatorial position and vegetative bacteria emerged by breaking open the cracks. In the following 180 min, the bacteria continued to grow without cell separation or the formation of flagella, so that, at 240 min, long filamentous forms of the vegetative bacteria were seen. Cell separation occurred at 300 min and simultaneously the development of flagella was observed. In liquid medium, the vegetative bacteria showed cell separation at an earlier stage (120 min) of outgrowth and flagella were visible at this stage. These results suggested that cell separation and flagella formation were closely related events. The role of autolytic enzymes in cell separation and flagella formation in relation to spore outgrowth is discussed.
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- Genetics And Molecular Biology
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Regulation of Sulphur Metabolism in Paracoccus denitrificans
More LessThe metabolic pathway for the reduction and incorporation of sulphate in Paracoccus denitrificans strain NCIB 8944 has been elucidated and the control and regulation of the pathway is reported. Several enzymes of the sulphate metabolic pathway have been assayed in P. denitrificans grown on different substrates. In addition, several enzymes have been purified and in vitro inhibitor studies conducted on them. Cysteine plays a primary role in the control of sulphur metabolism in P. denitrificans.
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Minicircular ColE1-related DNA in Strains of Klebsiella aerogenes Selected for Fast Growth on Xylitol
More LessWe have previously described a large family of mutants of Klebsiella aerogenes which were selected by continuous culture on xylitol and which superproduce ribitol dehydrogenase. One of these strains was found to harbour a high copy number 2·1 × 106 dalton plasmid. This plasmid is a deletion derivative of a low copy number 3·5 × 106 dalton plasmid present in the ancestral strain of K. aerogenes. However, since these plasmids do not contain the genes required for pentitol catabolism and some enzyme-superproducing strains have lost all DNA homologous to the plasmids, they are not implicated in the fast growth on xylitol. The plasmids contain regions of homology with the Escherichia coli plasmid ColE 1.
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The Assimilatory and Dissimilatory Nitrate Reductases of Pseudomonas aeruginosa are Encoded by Different Genes
More LessThe phenotypes of certain mutant strains of Pseudomonas aeruginosa were reported to be pleiotropic for nitrate reduction; these strains were selected for their inability to dissimilate nitrate and were found also to have lost the ability to assimilate nitrate. We now report that the isolation procedure selected two mutations, one in genes encoding the synthesis of dissimilatory nitrate reductase (narA, narB or narE) and another in one of the genes (nas) encoding the synthesis of assimilatory nitrate reductase. Thus in P. aeruginosa dissimilatory and assimilatory nitrate reductases are genetically distinct. However, a loss of both enzymes is necessary to prevent slow dissimilatory growth on nitrate. Assimilatory nitrate reductase requires molybdenum to function, as does dissimilatory nitrate reductase. Lesions in narD affect incorporation of molybdenum into both enzymes, and hence exert a pleiotropic effect.
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Phenotypic Stability of trp Operon Recombinant Plasmids in Escherichia coli
More LessThe recombinant plasmids RSF2124-trp and pSC101-trp were examined for their phenotypic stability in Escherichia coli W3110 and its derivatives under various culture conditions. RSF2124-trp and pSC101-trp were stable in a trpAE1 strain. In an amber mutant of the tryptophan repressor gene, RSF2124-trp was fairly stable, whereas pSC101-trp was unsTable All Trp- segregants from the pSC101-trp carrier had lost the entire plasmid. In a mutant carrying the tnaA mutation, RSF2124-trp was unstable in rich media. Most Trp- segregants that appeared under these conditions were deleted in trp genes as well as in the cI gene on the recombinant plasmid. pSC101-trp in this tnaA mutant was also unsTable All Trp- segregants had lost the plasmid. Studies of enzyme activities revealed that the greater the activity of anthranilate synthase and tryptophan synthase in bacteria, the more segregants tended to appear in the stability test. RSF2124 and pSC101 without the trp gene were completely stable in the same bacteria. The apparent instability of bacteria carrying the recombinant plasmid could be explained by the lower growth rate compared with bacteria carrying only the vector plasmid, resulting in the enrichment of Trp− bacteria during culture.
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- Immunology
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Evidence for Two Adhesive Antigens on the K99 Reference Strain Escherichia coli B41
More LessImmunoelectrophoresis and haemagglutination studies with a K99 antigen extract from the reference strain Escherichia coli B41 (O101: K99) demonstrated both anionic and cationic mannose-resistant haemagglutinins for horse red blood cells. Neither haemagglutinin was produced by bacteria grown at 18 °C. Antibodies to the cationic haemagglutinin were demonstrated in antisera to all the K99-positive E. coli strains in every serogroup examined, but antibodies to the anionic haemagglutinin were only detected in antisera to E. coli strains from the O9 and O101 serogroups. Inhibition of E. coli B41 adhesion to calf brush borders and indirect immunofluorescent staining indicated that the anionic haemagglutinin also exhibited adhesive properties.
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- Physiology And Growth
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Purification of the Insecticidal Toxin in Crystals of Bacillus thuringiensis
More LessCrystals were purified from, four serotypes of the insect pathogen Bacillus thuringiensis. Crystals from these serotypes were similar in amino acid and N-terminal analyses, but differed in their toxicity to two species of Lepidopter a and in their immunological properties. Toxic polypeptides were obtained following trypsin digestion of solutions of the crystals. In two strains (serotypes 3 and 9) this fraction contained only one polypeptide. Similar results were obtained when dissolved crystals were digested with other proteolytic enzymes or with gut contents from Pieris brassicae. The trypsin-resistant polypeptide was further purified by gel and ion-exchange chromatography and had a molecular weight of about 70000, estimated by gel chromatography and gel electrophoresis. No evidence was obtained for a toxin of lower molecular weight. This purified toxin accounted for most, if not all, of the toxic activity originally present in the crystal solution and was active by injection and ingestion. The purified toxic fraction from serotype 1 appeared to contain two polypeptides, one of which corresponded to that found with serotypes 3 and 9. There were no major differences in the composition of crystals from different serotypes of B. thuringiensis and it is concluded that the trypsin-resistant polypeptide represents the active insecticidal toxin of the crystal.
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Minimal Nutritional Requirements of Bacillus sphaericus NCTC9602 and 26 other Strains of this Species: the Majority Grow and Sporulate with Acetate as Sole Major Source of Carbon
More LessBacillus sphaericus NCTC 9602 grew and sporulated in a simple chemically defined minimal medium containing only KH2PO4/Na2HPO4 buffer, pH 7·2, 15 mm-ammonium sulphate, inorganic salts and sodium acetate (as sole source of carbon); no vitamins were needed. The organisms contained the characteristic enzymes of the glyoxylate cycle (isocitrate lyase and malate synthase) but lacked pyruvate dehydrogenase. Isocitrate dehydrogenase and 2-oxoglutarate dehydrogenase were both present.
The minimal nutritional requirements of 26 other strains of B. sphaericus were investigated. Three of these (including the type culture) grew and sporulated in the above minimal medium, and a further 13 strains grew and sporulated when only biotin and thiamin were added. Two more strains grew in the minimal medium plus these vitamins and glutamic acid. Four of the remaining strains needed several amino acids, but not acetate, and four other strains required a purine as well as amino acids.
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Multiplication of Toxoplasma gondii in Maturing Erythroid Cells
More LessMultiplication of Toxoplasma gondii was examined in vitro in murine erythroid cells at different stages of development. Toxoplasma gondii multiplied in nucleated erythroblasts and enucleated reticulocytes from the foetal liver, and in immature reticulocytes and yolk-sacderived erythrocytes from the foetal circulation. However, the rate of multiplication was lowered as erythroblasts matured, and multiplication was not detected in foetal erythrocytes. A decrease in the multiplication rate with maturation was also observed with yolk-sac erythrocytes.
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