- Volume 87, Issue 2, 1975
Volume 87, Issue 2, 1975
- Biochemistry
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Isolation of an Inducible Amidase from Pseudomonas acidovorans AE1
More LessSUMMARY: A bacterial strain, AE1, which hydrolysed acetanilide, was isolated from soil and identified as Pseudomonas acidovorans. Numerous amides, esters and enzyme inhibitors were tested as amidase inducers. Phenacetin was chosen as inducer for the large scale cultivation of these organisms because it was less toxic to the bacteria than acetanilide. The induction increased the enzymic activity 250-fold. In comparison, the type culture strain of P. acidovorans, ATCC15668, had no amidase activity which could be induced phenacetin. Optimal growth conditions were established with respect to the concentration of carbon source and inducer so that about 10% of the extractable bacterial protein consisted of the amidase. The organisms were lysed with lysozyme in the presence of EDTA and the enzyme was isolated mainly column chromatography procedures. A preparation from 60 g (wet wt) bacteria yielded about 100 mg highly purified amidase with a specific activity of 137 μmol substrate hydrolysed/min/mg protein. In addition to acetanilide, the purified enzyme hydrolysed several other amides and esters. As standard substrate, p-nitroacetanilide was chosen.
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β-Lactamases from Yersinia enterocolitica
More LessSUMMARY: Two β-lactamases, A and B, have been shown to be present in a strain of Yersinia enterocolitica (W222). β-Lactamase A hydrolyses a variety of penicillins and cephalosporins. This enzyme is sensitive to thiol reagents, is only partially inhibited 0·1 mm-cloxacillin and has a molecular weight of approximately 20000. β-Lactamase B shows strong cephalosporinase activity but does not hydrolyse some of the penicillins. It is more resistant than β-lactamase A to thiol reagents, is completely inhibited 0·1 mm-cloxacillin and has a molecular weight of about 34000. With cephaloridine as a substrate, which is readily hydrolysed both enzymes, about 85% of the total activity of a cell extract is due to β-lactamase A and 15% to B. Addition of 6-aminopenicillanic acid to the culture during growth results in a 2- to 4-fold selective increase in the amount of β-lactamase B. Two β-lactamases similar to enzymes A and B have been found in five other strains of Y. enterocolitica. In contrast, only one β-lactamase, similar to enzyme B, has been detected in a different strain of Y. enterocolitica (H66), which is abnormal in that it is sensitive to ampicillin. Addition of 6-aminopenicillanic acid to cultures of this strain results in an 8- to 10-fold increase in β-lactamase production.
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An Insect Toxin from Spores of Bacillus thuringiensis and Bacillus cereus
More LessSUMMARY: Spores of Bacillus thuringiensis contain a toxin active against lepidopterous larvae. This toxin can be solubilized extraction with reagents which dissolve the protein crystal of B. thuringiensis. It is inactivated crystal-specific antiserum. Spores of Bacillus cereus contain a similar toxin although the specific activity is much lower than the spores of B. thuringiensis. The B. cereus toxin contains a single major polypeptide component. Toxic activity can be solubilized from spores of both species incubation with gut juices from Pieris brassicae.
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- Development And Structure
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Nature of the Determinant Responsible for the Adhesion of Lactobacilli to Chicken Crop Epithelial Cells
More LessSUMMARY: Using an in vitro method, some factors affecting the attachment of a strain of lactobacillus to chicken crop epithelial cells have been studied. Time of contact beyond 10 min, pH value, age or growth temperature of the bacterial culture, or nature of the energy source in the growth medium had little or no effect on attachment. Heating to 100 °C for 10 min, or treatment with EDTA or surface active compounds was also without effect. Treatment with sodium periodate markedly decreased adhesion, proteolytic enzymes had a smaller effect but wheat germ lipase was completely inactive. The pronounced inhibition of adhesion periodate suggested the involvement of carbohydrate. However, enzymes known to attack carbohydrate substrates were inactive in reducing adhesion. Concanavalin A, which binds specifically to certain sugar residues, reduced attachment. It is suggested that these concanavalin A receptors on the lactobacillus are responsible for its attachment to crop epithelial cells.
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Early Ontogenetic Stages in Dolipore/Parenthesome Formation in Polyporus biennis
More LessSUMMARY: Sheared hyphae of Polyporus biennis, allowed to grow for 15 h, showed a number of stages of dolipore/parenthesome formation. These included: the proliferation of new endoplasmic reticulum from the nuclear envelope; the differentiation of endoplasmic reticulum into parenthesomes that initially were conjoined and free in the cytoplasm; the immature appearance of the electron-transparent dolipore shell; and the development of the apertural kernel into the occlusions at the dolipore orifices.
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Regulation of Coremium Morphogenesis in Penicillium claviforme
More LessSUMMARY: Coremia of Penicillium claviforme develop in three stages: primordium formation, elongation, and sporulation. Primordium formation was induced external nutrients, while starvation initiated the differentiation of primordia into coremia with sporeheads. There is strong evidence that external nutrients are not taken up during this differentiation. Continued sporulation mature coremia again required an external nutrient supply.
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- Genetics And Molecular Biology
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Changes in Ribosomes Associated with Spore Senescence in the Bean Rust Fungus
More LessStudies were carried out to identify the cause of the decline in transferase activity and capacity to bind polyuridylic acid which occurs in ribosomes from germinated uredospores of the beam rust fungus, Uromyces phaseoli (Pers.) Wint., aged longer than 6 h on a water surface. We have shown that such ribosomes lose the capacity to respond to added transferase-1 and that both subunits were affected by the ageing process. these changes were not accompanied by a significant alteration in the composition of teh ribosome. However, deoxycholate had a greater detergent effect on ribosomes from germinated spores than from nongerminated spores as shown both by loss of capacity to polymerize anino acids and loss of protein. Ribonuclease activity did not increase during germination, but the amount found (1 μg/g spores) was easily detectable. It was suggested that loss of response to transferase-I was due to an alteration of ribosomal proteins of both subunits.
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Transfer of Drug Resistance to Myxococcus from Bacteria Carrying Drug-resistance Factors
More LessResistance to chloramphenicol was successfully transferred from strains of Escherichia coli carrying R factors representative of compatibility groups F, W, S and N to strains of Myxococcus xanthus and M. fulvus. Resistance to kanamycin was transferred from an R factor in group S, and to neomycin from an R factor of group P. Myxobacterial strains differed in their capacity to take up the resistances and also in the stability of the resistance character. Strains of M. fulvus were obtained that acquired resistance to chloramphenicol without exposure to R+ eubacterial strains. Cell-free preparations of all the chloramphenicol-resistant strains catalysed the acetylation of the drug. Chloramphenicol resistance was successfully transferred from the presumed R+ strains of Myxococcus and also from the spontaneously occurring chloramphenicol-resistant M. fulvus to other Myxococcus strains. Moreover, recombinants resistant to both rifampicin and 5-fluorouracil were obtained, though infrequently, mixing Myxococcus strains resistant to rifampicin and chloramphenicol with other myxococci resistant to 5-fluorouracil, both when the chloramphenicol resistance was derived from S-a (group W) and when it was the endogenous M. fulvus resistance. Thus it appears that S-a and a new chloramphenicol resistance factor from M. fulvus will mobilize a chromosomal genetic marker in Myxococcus.
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Restriction of DNA in Yersinia enterocolitica Detected Recipient Ability for a Derepressed R Factor from Escherichia coli
G. Cornelis and C. ColsonSUMMARY: A derepressed R factor, RY2drd2, was transferred at a frequency of 5 × 10−3 between two strains of Yersinia enterocolitica mated on a membrane. Under the same conditions transfer of this R factor from Escherichia coli to Y. enterocolitica was observed at a frequency of only 7·7 × 10−6. This frequency was greatly increased when the recipient strain was heat-treated before mating. Heat exposure for optimum fertility was 50 to 52 °C for a period of 2 to 3 min. Mutants of Y. enterocolitica were isolated which were infected RY2drd2 from E. coli or from Y. enterocolitica at the same frequency. These observations strongly suggest that a DNA restriction and modification system in Y. enterocolitica causes its low recipient ability for plasmids from other species.
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R Factors from Proteus mirabilis and P. vulgaris
More LessSUMMARY: Eighty-nine R factors were transmitted conjugation to Escherichia coli k12 from isolates of Proteus hauseri (P. mirabilis plus P. vulgaris). More than half were non-selftranmissible. The remainder included plasmids assigned to the previously defined groups FII, A-C complex, J, N and P, as well as some not belonging to any known compatibility groups. R factors from strains isolated in India, Thailand and Japan carried plasmids whose inheritance was extremely unstable in E. coli k12. All belonged to a new compatibility group, V.
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Construction and Phenotypes of Double Sporulation Deficient Mutants in Streptomyces coelicolor A3(2)
More LessSUMMARY: In whiA, B, G and H mutants of Streptomyces coelicolor A3(2), aerial hyphae develop but sporulation septa are not formed. Septa are produced whiI mutants but are spaced abnormally far apart. Mutants in each locus have a distinctive aerial mycelium morphology, except for whiA and B mutants which are closely similar. Seven strains were made with pairwise combinations of whiA and B mutations with whiG, H and I mutations and with each other. The genotypes of these strains were confirmed suitable crosses and their aerial mycelium morphology examined. An indirect procedure was used to determine the aerial mycelium morphology of whiGH, GI and HI double mutants. The double mutants always closely resembled one of the single mutant parent strains in morphology and a consistent scheme of epistasis was obtained −whiG being epistatic to whiH, A, B and I; whiH to whiA, B and I; and whiA or B to whiI. These results point to the absence of any complex interactions between gene products, which might have been revealed the occurrence of novel phenotypes in double mutants or inconsistencies in the epistasis scheme.
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Chemical Mutagenesis of Fusarium oxysporum f. sp. lycopersici: Non-selected Changes in Pathogenicity of Auxotrophic Mutants
More LessSUMMARY: Single and multiple auxotrophic mutants of the Fusarium oxysporum f. sp. lycopersici strains which cause Fusarium crown-rot and Fusarium wilt of tomato were obtained chemical mutagenesis with nitrous acid, nitrosoguanidine and ethyl-methanesulphonate. The mutagenesis and selection procedures, adapted for use with a plant pathogenic fungus, are described. Changes in pathogenicity were observed when the auxotrophs were compared with the wild type but no correlation was observed between changes in pathogenicity and the particular nutritional requirement.
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Identification of the Rhizobium Strains in Pea Root Nodules Using Genetic Markers
More LessSUMMARY: Pea plants were inoculated jointly with pairs of genetically marked strains of Rhizobium leguminosarum. Out of 297 nodules examined 56 contained both inoculant strains. The ratios of the strains in the inoculum did not affect the frequencies of mixed nodules. Generally one of the strains consistently occupied the majority of the nodules and in the mixed nodules comprised the majority of bacteria. Transfer of the P-group R factor, RP4, between certain strains of Rhizobium within mixed nodules was detected. In some cases the non-parental progeny comprised 10 % of the rhizobia isolated from such nodules.
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- Medical Microbiology
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The Identification and Purification of Multiple Forms of θ-Haemolysin (θ-Toxin) of Clostridium perfringens Type A
More LessThe θ-haemolysin of Clostridium perfringens was purified from culture supernatant fluids of type A strains fractional ammonium sulphate precipitation and isoelectric focusing in narrow pH 5 to 8 gradients. Four components detected on electrofocusing were designated θ 1 (p1 6·8 to 6·9),θ 2 (p1 6·5 to 6·6),θ 3 (p1 6·1 to 6·3) and θ 4 (p1 5·7 to 5·9). Specific activities ranged from 0·4×106 to 1·2×106 haemolytic units/mg protein and 2950 to 3600 LD50/mg protein. Each haemolytic component was activated cysteine hydrochloride, and inactivated cholesterol, addition of sheep erythrocyte ghosts and heating at 60 ° C for 10 min; mouse erythrocytes were more resistant than sheep erythrocytes to haemolysis. A reaction of identity was obtained between components in gel diffusion. Sodium dodecyl sulphate polyacrylamide disc gel electrophoresis gave molecular weights in the range 59000 to 62000 for each component. A similar value was obtained for θ 1 on density gradient ultracentrifugation. Although the multiple forms were free of 11 factors present in culture supernatants, crossed immunoelectrophoresis and disc gel electrophoresis revealed minor contaminants. These studies reveal that θ-haemolysin has physical properties in common with other oxygen-labile haemolysins.
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Taxonomic Distribution of the Antigen Eliciting Bactericidal Antibody for Bordetella pertussis
More LessSUMMARY: Strains of Bordetella pertussis varied in their ability to elicit (in mice) an antibody bactericidal for an antiserum-sensitive strain of B. pertussis, although antibody was usually detectable after only one injection. High titres were produced a course of seven injections with all strains of B. pertussis tested (six of phase I and three of phase IV) but not with three strains of other Bordetella species nor with two unrelated organisms, a finding of possible taxonomic value.
Preliminary investigations have not revealed whether strain variations are due to quantitative or qualitative differences in either the bacterial lipopolysaccharide or the carrier protein necessary for antibody production, or whether they may be due to differences in heat lability of ‘bactericidal antigen’.
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- Physiology And Growth
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Polyene Sensitivity during Germination of Conidia of Aspergillus fumigatus
More LessSUMMARY: A system for the rapid and relatively synchronous germination of conidia from a clinical isolate of Aspergillus fumigatus is described. The polyene-mediated release of K+ from germinating conidia has been determined. Ungerminated conidia were insensitive to amphotericin B methyl ester (AME) at concentrations > 50 μg/ml, but rapidly became sensitive to 1 to 2 μg AME/ml during the initial stages of germination. These findings have been correlated with minimum inhibitory concentration values obtained in studies of conidial germination and hyphal outgrowth using a variety of growth tests.
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- Short Communications
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- Taxonomy
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Taxonomic Position and Seasonal Variations in Marine Neritic Environment of Some Gram-negative Antibiotic-producing Bacteria
More LessSUMMARY: Six marine bacteria which synthesize macromolecular antibiotics were isolated from neritic waters on the French Mediterranean coast, and their frequency recorded over two successive years.
They appeared in relatively large numbers during the period August to December, and can be identified as marine pseudomonads; however, the low guanine-cytosine ratio of their DNA, lack of catalase and specific self-inhibition are not compatible with the characteristics of the genus Pseudomonas. Two produced violacein, usually synthesized bacteria belonging to the genus Chromobacterium. Their taxonomic position is discussed.
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