摘要:

The synthesis of catalase (H2O2:H2O2oxidoreductase, EC 1.11.1.6) inEscherichia coli K12was regulated by repression–induction and catabolite repression. Transient repression by glucose was also demonstrated. Under certain conditions, preferential synthesis was observed. Enzyme synthesis was induced in glycerol-grown cells by 0.15 to 0.2 μmol H2O2(5–6 μg) per millilitre of culture, added at 10 to 15-min intervals, which were shortened progressively as the level of catalase in the cells rose. Catabolite repression of catalase synthesis was demonstrated with glucose, glycerol, maltose, lactose, xylose, mannitol, sorbitol, and trehalose, and to a lesser extent with arabinose, galactose, sucrose, rhamnose, and dulcitol as sole carbon sources in mineral medium. Catabolite repression was prevented by anaerobic growth and nitrogen starvation. All TCA-cycle intermediates examined afforded high catalase levels when serving as sole carbon sources. High catalase levels were also obtained when cells were grown on nutrient broth, nutrient agar, casitone, and peptone.

ISSN:0008-4166    

DOI:10.1139/m77-011

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A short incubation solid-phase radioimmunoassay test was developed and used for the detection of hepatitis B surface antibody (anti-HBs) in the sera collected from patients recovering from hepatitis B infection, health care personnel, staff and residents of an institution for the mentally retarded and in pregnant and non-pregnant women in Ontario. The test was slightly more sensitive than the passive haemagglutination method (PHA) and less sensitive than the Ausab Radioimmunoassay technique (RIA).The prevalence of anti-HBs in different populations tested ranged from 0 to 44.3%. They were classified according to the statistical analysis into three main categories: low, intermediate, and high risk. Students and administrative staff were in the low-risk category, Microbiology, histology, pathology technologists, renal dialysis staff, and the health care personnel responsible for the care of the institutionalized mentally retarded were in the intermediate-risk category. Pathologists, haematologists, and biochemists were in the high-risk category. The results showed that health care personnel who were exposed to blood or blood products had a higher frequency of anti-HBs than those who were not exposed.

ISSN:0008-4166    

DOI:10.1139/m77-012

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

All bovine sera tested contained agglutinating immunoglobulins against encapsulatedStreptococcus bovis. The immunoglobulins also were shown in predominantly parotid saliva. Cells grown in broth with added carbohydrate (sucrose) produced extracellular dextran (capsule) and were agglutinated by sera and saliva, butS.boviscells grown in absence of carbohydrate were not agglutinated. The reacting material was established by adsorption with mono-specific anti-bovine gamma globulin to be an immunoglobulin. Sephadex adsorption studies showed the immunoglobulin specific to extracellular dextran. Sephadex adsorption also provided a way to isolate these immunoglobulins. Purified capsular dextran demonstrated a precipitin reaction with serum and saliva preparations. BecauseS.boviscapsule has been implicated in feedlot bloat, it is possible that antibodies reaching the rumen in bovine saliva may affect bloat.

ISSN:0008-4166    

DOI:10.1139/m77-013

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Proteus mirabiliswas examined on an agar surface with scanning electron microscopy after critical-point drying. Groups of swarm cells were covered by a thin cocoon. The cocoon appears identical with the slime found covering the agar surface behind rafts of swarm cells. Swarm cells possessed numerous appendages that resemble peritrichous flagella in number, size, location, and attachment to the cells.

ISSN:0008-4166    

DOI:10.1139/m77-014

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Ergosterol, the principle sterol of many wild-typeNeurosporaand other Ascomycetes, had a greater affinity for polyene antibiotics than did lichesterol or eburicol, the sterols of some resistant mutant strains. The affinity was demonstrated by comparing the sterols extracted from sensitive and resistant strains ofNeurospora crassaandCandida albicansfor protection against polyene inhibition of sensitiveN.crassaand for their ability to alter specific polyene absorption maxima.

ISSN:0008-4166    

DOI:10.1139/m77-015

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The influence of simulated diving environments on the antimicrobial activity of a variety of penicillin and cephalosporin congeners was studied inStaphylococcus aureus. Pressure reduced bacteriostatic action provided the antibiotic was susceptible to β-lactamase hydrolysis and the bacterium was inducible for penicillinase. Ethidium bromide curing of the penicillinase plasmid of an inducible strain eliminated the hyperbaric effect. The minimal inhibitory concentration of benzylpenicillin increased about threefold with increasing hyperbaric pressure from 17 to 136 atm. Additional pressurization to 204 atm did not change antibiotic efficacy further. The efficacy of benzylpenicillin was reduced by 68 atm of hyperbaric helium, nitrogen, or a mixture of neon and helium, but was slightly increased by 68 atm of argon, removal of the gas phase, or 68 atm of hydrostatic pressure. Hyperbaric helium had no effect on β-lactamase activity in vitro. An effect was demonstrated upon induction by suboptimal concentrations of methicillin. The concentration of methicillin required for the induction of half-maximal levels of penicillinase in late log cultures ofS.aureuswas reduced from 0.15 μg/ml at 1 atm to 0.06 μg/ml at 68 atm. The basis of increased resistance to antibiotics exhibited byS.aureusin hyperbaric environments appears to be enhanced efficiency of penicillinase induction.

ISSN:0008-4166    

DOI:10.1139/m77-016

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Neisseria gonorrhoeaecells are effectively disrupted with a synthetic zeolite, type 4A. The soluble material released from gonococci contains antigen(s) which are involved in the immune response to gonorrhea in experimentally infected chimpanzees and are common to different gonococcal strains.

ISSN:0008-4166    

DOI:10.1139/m77-017

出版商:NRC Research Press    

年代:1977

数据来源: NRC