摘要:

Strains resistant to the action of sulfa drugs and tetracycline were predominant among the antibiotic-resistantSalmonella typhimuriumphagovar 204 isolated in Canada. Plasmid DNA was detected in cellular extracts of all strains examined. A number of these plasmids could be placed in specific incompatibility and size classes. Both resistance coding and cryptic plasmids were involved in determining phagovar 204. In one instance, phagovar 204 was derived from phagovar 36 in a two-step conjugation involving independent sulfadiazine and tetracycline resistance plasmids. In another, phagovar 204 was derived directly from phagovar 49 through the introduction of a single tetracycline–streptomycin R plasmid. The phagovar-determining plasmids ranged in size from 3.4 to 72 megadaltons.

ISSN:0008-4166    

DOI:10.1139/m82-149

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Municipal water samples were analyzed by membrane filter (MF) and presence–absence (P-A) tests for pollution indicator bacteria. In four years, 11 514 bacterial cultures were isolated from either raw water, drinking water, or new main water samples submitted to three environmental laboratories. The bacterial species occurring most often in all types of water samples wereEscherichia coli(11.6–39.7%),Enterobacter aerogenes(18.1–26.3%),Aeromonas hydrophila(8.8–17.0%),Klebsiella pneumoniae(7.7–10.3%), andCitrobacter freundii(5.09–22.7%). A lactose – lauryl tryptose – tryptone broth was examined as an alternative medium to modified MacConkey broth in the presumptive portion of the P-A test. The intensity of acid and gas production in presumptive positive P-A bottles was compared with the types and frequencies of indicator bacteria shown by confirmatory tests. The results of detecting indicator bacteria following the analysis of 53 130 samples over a 2-year period were arranged by water source (well, lake, river, mixed) and water type (raw or drinking) to determine the influence of these parameters on the recovery of indicator bacteria. A further subdivision of the sample types into raw surface, raw ground, in-plant, plant discharge, reservoir, and distribution samples demonstrated the effect of water treatment practices.

ISSN:0008-4166    

DOI:10.1139/m82-150

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Physicochemical methods have been used to compare mycoplasma DNA capable of the genetic transformation of tetracycline resistance with DNA from tetracycline-sensitive mycoplasmas and their transformants. These mycoplasmas were isolated from human patients. The DNA extracted fromMycoplasma hominis tetrresistant to 100 μg/mL tetracycline transforms tetracycline resistance to sensitive strains ofMycoplasma salivarium tetsandMycoplasma hominis tetsbut notMycoplasma fermentans tets. Bulk DNA and DNA extracted by methods which increase the yield of circular DNA moieties were analyzed by cesium chloride and cesium chloride – ethidium bromide buoyant density ultracentrifugation and by horizontal and vertical agarose gel electrophoresis. Extrachromosomal DNA was not detected, which suggests that transformation was mediated by the recombination of chromosomal genes for tetracycline resistance and not by R factors. Moreover, no significant differences were detected in the DNA from the resistant and sensitive species or from their transformants andMycoplasma fermentans tetswhich could not be transformed to resistance to 10 μg tetracycline/mL medium.

ISSN:0008-4166    

DOI:10.1139/m82-151

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Curvularia coicistransforms glycocholic acid, but not cholic acid, in whole cell cultures to deoxycholic acid in 3% yield. Cell-free extracts can act on both substrates to yield deoxycholic acid. Still cultures, as well as cell-free extracts, ofC.coicisdehydroxylate glycocholic acid (7α hydroxyl group) to glycodeoxycholic acid.

ISSN:0008-4166    

DOI:10.1139/m82-152

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Cross-protection has already been demonstrated in mice after vaccination with a CaCl2extract from theNeisseria meningitidesgroup Y Slaterus strain. The immunogenicity of such extracts from group Y cells, cultivated in a fermenter in Neisseria chemically defined medium, against virulent groups A, B, and C meningococci has been evaluated by two different animal models and a microbactericidal procedure. The mouse challenge system has revealed that the active cross-production observed 7 days after a single immunization with the extract was probably nonspecific, since bacillus Calmette-Guérin gave similar results. However, after three vaccinations, active cross-protection was observed, mainly against the strains of groups B and C, for at least 35 days after the last injection. In the mouse bacteremia model, the extract had a protective effect mainly against the homologous group Y strain but in a few experiments a significant protection was also obtained against the strains of groups A and B. The microbactericidal test revealed that even after three injections of mice, guinea pigs, or humans with the extract only the homologous bactericidal activity was induced. Since there was no close correlation between the results obtained with the two animal models and also with the microbactericidal procedure, no definitive conclusion can be drawn on the protective potential of our extract.

ISSN:0008-4166    

DOI:10.1139/m82-153

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Clostridium perfringensstrain No. 28 and its penicillin-induced stable L form were treated with 10 different bacteriocins ofC.perfringens. Viable count and labelled amino acid incorporation experiments revealed that the L form was sensitive to two and possibly three bacteriocins to which the bacillus was not, while both forms were commonly sensitive to two other bacteriocins and resistant to five others. Adsorption of bacteriocin, immunity factors, or perhaps uptake of bacteriocin might be proposed to explain the responses of these organisms to bacteriocins.

ISSN:0008-4166    

DOI:10.1139/m82-154

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Alcaligenes faecalis, grown on 3-cyclohexenecarboxylic acid supplemented with gluconate, was induced to metabolize cyclohexanecarboxylic acid, 3-cyclohexenecarboxylic acid, 1, 4-cyclohexadienecarboxylic acid, benzoic acid, and catechol. During growth, 1, 4-cyclohexadienecarboxylic acid, 3-heptene-1, 7-dioic acid, and benzoic acid were shown to be present in the culture supernatants. The results suggest that 3-cyclohexenecarboxylic acid may be metabolized by two pathways having 1, 4-cyclohexadienecarboxylic acid as a common intermediate. One pathway involved β-oxidation of coenzyme A intermediates; the other pathway involved benzoic acid as an intermediate. Studies on the consumption of oxygen per mole of substrate by cell suspensions indicated that the major portion of 3-cyclohexenecarboxylic acid was metabolized by the pathway involving benzoic acid. When grown on 3-cyclohexenecarboxylic acid as sole carbon and energy source, the organism was additionally induced to metabolize salicylic acid and gentisic acid, and growth medium contained salicylic acid. Thus, under the latter growth conditions a pathway involving salicylic acid as an intermediate was also induced.

ISSN:0008-4166    

DOI:10.1139/m82-155

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Electrophoretic analysis of three dehydrogenase and two reductase isozymes was performed on 18 commonly used yeast strains. Gene polymorphism was noted for all five isozyme activities. Based on the homology of banding patterns, two main groups of yeast strains were identified. No two yeast strains had identical banding patterns.

ISSN:0008-4166    

DOI:10.1139/m82-156

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Heterotrophic bacteria were isolated from wetland soil, rhizosphere soil, root and basal shoot of wetland rice, dryland soil, and root of dryland rice. The isolates were tested for N2-fixing activity and the ability to grow autotrophically under H2 + CO2 + O2. N2-fixing bacteria capable of autotrophic growth were found almost exclusively from the rhizosphere and the root of wetland rice. In another experiment, all N2-fixing bacteria isolated from wetland rice root had uptake hydrogenase activity. These findings indicate the predominance of hydrogen-utilizing bacteria among N2-fixing bacteria from wetland rice roots.

ISSN:0008-4166    

DOI:10.1139/m82-157

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The inorganic ions magnesium and potassium were required for optimal growth ofLegionella pneumophilain a chemically defined medium composed of amino acids and inorganic salts. Optimum growth was obtained at concentrations of approximately 20 μg/mL (80 μM) MgSO4∙7H2O and 150 μg/mL (2 mM) KCl. Comparable results were obtained with all six serogroups ofL.pneumophilaas well as with both laboratory-adapted and animal-passed strain

ISSN:0008-4166    

DOI:10.1139/m82-158

出版商:NRC Research Press    

年代:1982

数据来源: NRC