摘要:

Proteus vulgarismetabolized thiosulfate to H2S. The amount evolved and its sulfur isotope composition identified it solely with sulfane sulfur. In contrast.Salmonella heidelbergsequentially reduced the sulfane sulfur of S2O32−with slight enrichment of the evolved sulfide in32S and then reduced the sulfonate sulfur of S2O32−with large isotopic selectivities and an inverse isotopic fractionation pattern. The inverse isotope fractionation pattern for the H2S derived from the sulfonate sulfur was almost identical to that observed during the reduction of high concentrations of sulfite byS.heidelberg.

ISSN:0008-4166    

DOI:10.1139/m80-196

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Experiments were designed to characterize a number of oral "pigmented"Bacteroidesisolates with regard to their pathogenicity in an experimental model system and a number of other properties. These include fatty acid determination, hemagglutination studies, collagenase and protease activities, and vitamin K. dependency. OralB.asaccharolyticusandB.melaninogenicusisolates differed from one another in phenylacetic acid production, hemagglutination, collagenase activity, and pathogenicity. AllB.asaccharolyticuswere found to be pathogenic in thein vivomixed infection model and this property could be correlated with biochemical and enzymatic activities.

ISSN:0008-4166    

DOI:10.1139/m80-197

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The quantification of psychrophilic/psychrotrophic and mesophilic, heterotrophic bacteria from a lake which experiences seasonal temperature fluctuations showed that the psychrophilic/psychrotrophic population ranged in number from 1212 to 87 000/mL, whereas the mesophilic population ranged from 67to3783/mL, for sediment–water interface samples over the yearly cycle. The relative abundance of psychrophiles/psychrotrophs and mesophiles varied with season, but psychrophilic/psychrotrophic bacteria were found to predominate on every sampling occasion. A considerable number of the 37 °C isolates were found to be psychrotrophs having broad temperature ranges for growth. An especially notable result was the isolation of psychrophiles on every sampling occasion, and in such high numbers, from this "nonpermanently cold" environment.A total of 388 isolates were described according to Gram reaction, colony and cell morphology, biochemical activities, and thermal type, and on the basis of similarities they were grouped into 158 "working types." Many of the "working types" were capable of gelatinase, amylase, chitinase, and lipase production.A comparison of the generation times of the psychrophilic/psychrotrophic and mesophilic "working types" with their frequencies of occurrence, for all four samplings, did not reveal a direct relationship between numerical predominance and growth rate as determined by temperature.

ISSN:0008-4166    

DOI:10.1139/m80-198

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The capacity of a pure culture of anaerobic intestinal bacteria to influence the host's cellular and humoral immune systems was investigated with germfree, monoassociated, and conventionally reared rats. Monoassociation of germfree rats withBacteroides fragilisstimulated the production of serum gamma globulin, agglutinating antibodies, and an apparent IgG (Immunoelectrophoresis) band. A comparison of thein vitroblastogenic potential of lymphocytes (spleen cells and mesenteric lymph node cells) from germfree, monoassociated, and conventionally reared rats indicated the following: (1) the microbial flora had no obvious effect on the capacity of nonstimulated lymphocytes to incorporate [3H]thymidine; (2) spleen cells from conventionally reared rats responded to phytohemagglutinin, concanavilin A, or pokeweed mitogen better than splenocytes from germfree rats; (3) colonization of germfree rats withFusobacterium necrophorumincreased the responsiveness of splenocytes to photohemagglutinin and concanavilin A; and (4) monoassociation of germfree rats withB.fragilis. but not withF.necrophorumorPropionibacterium acnes, increased splenocyte blastogenesis to homologous (i.e., colonizing) bacterial antigens. This study indicated that some intestinal bacteria can modulate the immune status of the host; the extent and nature of this modulation depended on the particular species of colonizing bacteria.

ISSN:0008-4166    

DOI:10.1139/m80-199

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Hybridization studies based on the prototrophic selection technique involving the use of auxotrophic mutants of sevenSchwanniomycesstrains are reported.Recombinant formation was not detected in any of the 87 experiments comprising both intrastrain and interstrain crosses of strains previously identified asS.alluvius,S.castellii,S.occidentalis, andS.persoonii.

ISSN:0008-4166    

DOI:10.1139/m80-200

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Intestinal infections are a major cause of mortality in domestic rabbits. Although a few pathogenic organisms have been associated with this type of infection, it is often impossible to demonstrate the presence of any etiologic agents.Recently viral particles were observed in the intestine of diseased rabbits submitted to our laboratory for diagnosis. A study was then initiated to evaluate the presence of viral agents in the intestine of rabbits showing clinical signs of enteritis. Viral particles with morphological characteristics of the Coronaviridae family were observed by electron microscopy in most specimens of fecal material obtained from sick rabbits. Such particles were not seen in the feces of healthy animals.These particles, which have a density of 1.07–1.18 g/cm3on sucrose gradient, hemagglutinate rabbit red blood cells. Furthermore this virus has some antigenic relationship with the human coronavirus 229-E since immune serum to this virus blocks the hemagglutination of the rabbit erythrocytes.Antibody titers to this virus were detected in rabbit sera obtained from colonies with a high incidence of intestinal infections.When fecal material containing coronavirus particles were inoculated on various tissue culture systems, no cytopathic effects were observed.

ISSN:0008-4166    

DOI:10.1139/m80-201

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

An examination of conditions for the growth ofDesulfovibrio desulfuricans, with the aim of optimizing hydrogenase production, is reported. An ammonium sulfate – lactate – yeast extract medium gave 5 to 10 times as much hydrogenase activity as a peptone – yeast extract medium. It made little if any difference whether the gas used for sparging was nitrogen, hydrogen, or a mixture thereof but increasing the rate of sparging and agitation did result in a slight decrease in activity. Control of pH during culture development was of little benefit to hydrogenase production. At least two hydrogenases were present inD.desulfuricans: one periplasmic, the other membrane bound.Desulfovibrio desulfuricansproduced more hydrogenase than did eitherD.gigasandD.vulgaris.

ISSN:0008-4166    

DOI:10.1139/m80-202

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The periplasmic hydrogenase ofDesulfovibrio desulfuricanswas isolated and purified. Cells were washed with Tris–EDTA and the enzyme precipitated from the wash with ammonium sulfate. Absorption chromatography on DEAE and hydroxyapatite yielded the enzyme at better than 95% purity as judged by gel electrophoresis. The hydrogenase catalyzed the production of more than 9000 μmol H2/min mg protein−1from reduced methyl viologen at 37 °C. It is very stable and resists inactivation by heat (50% activity remained after 5 min in air at 65 °C) and by enzyme inhibitors (exceptN-ethylmaleimide and potassium ferricyanide). After storage in air at 4 °C for 1 month no activity was lost. The enzyme activity is sensitive to ionic environmental changes. With methyl viologen the optimum pH was 5.5 but withp-xylene polymeric viologen the optimum was about pH 7 but less sharp. The molecular weight was 47 × 103(± 2 × 103), 52 × 103(± 2 × 103), and 56 × 103(± 2 × 103) by SDS –gel electrophoresis, gel chromatography, and sedimentation equilibrium, respectively, and the isoelectric point was at pH 6.0. The enzyme consists of one polypeptide chain terminated at the amino end by proline. This enzyme might be useful in the production of hydrogen from water and solar energy.

ISSN:0008-4166    

DOI:10.1139/m80-203

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

An endonuclease activity has been purified from human adenovirus type 5 (HAd5) virions and HAd5-infected cell extracts. The endonuclease activity is associated with a monomeric protein of molecular weight approximately 33 000. The endonuclease activity is more active at pH 4.5 than pH 7.2. Incubation of the enzyme at room temperature for periods of longer than 96 h results in a substantial increase in activity. The endonuclease activity is sensitive to EDTA at concentrations 10 mMor greater but is insensitive to 500 mMNaCl. Immunological analysis with endonuclease specific antiserum indicates that the endonuclease may be a host cell derived, viral modified, and incorporated protein.

ISSN:0008-4166    

DOI:10.1139/m80-204

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

A broth medium which provided for optimum growth ofYersinia enterocoliticawas formulated. In this mediumY.enterocoliticagrew best at pH 7.6–7.9 and 32 °C with a generation time of 33–39 min depending upon the strain. Examination of various chemicals as potential selective agents in an agar medium showed a high tolerance for surface-active agents, but cetrimide, 4-nitrophenol, potassium tellurite, and sodium azide were inhibitory at very low concentrations. Irgasan was tolerated at concentrations inhibitory to some other Enterobacteriaceae. Minimum inhibitory concentrations for 57 antibacterial agents tested against 18 strains suggested that carbenicillin, novobiocin, and SCE-129 (cefsulodin) might serve as useful agents for selective isolation ofY.enterocolitica.

ISSN:0008-4166    

DOI:10.1139/m80-205

出版商:NRC Research Press    

年代:1980

数据来源: NRC