摘要:

Bacteriophage PBS 1 adsorbs initially on the flagella of its host,Bacillus subtilis(stage I). The phage can adsorb to both active and inactive flagella. Flagellar attachment is nonspecific as PBS 1 was shown to attach to the flagella ofBacillusspecies other than the normal host,B.subtilis. The phage particle then quickly moves down the length of the flagellum to its base, the final adsorption site. Flagellar motion is required for flagellar base attachment (stage II). After proper attachment at the flagellar base, the phage tail sheath contracts sending the tail core through the final adsorption site (stage III). The phage DNA is then injected at this site (stage IV). Stage I adsorption does not cause loss of motility in PBS 1 – resistant bacilli. The loss of motility observed upon infection of sensitive cells by PBS 1 may be associated with either stage II or stage III of adsorption.

ISSN:0008-4166    

DOI:10.1139/m78-001

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A comparative study of the consequences of Parainfluenza type 1 (Sendai) virus infection in inbred (C57B1/6J, C57Br, CBA, DBA) strains and a randomly bred (Swiss white) strain of mice showed significant mortality in the inbred strains but not in the randomly bred ones. This difference may be partly related to the high levels of virus growth obtained in the lungs of the inbred strains contrasted to little or no virus growth in the lungs of the Swiss white mice. A similar difference between these mice was found in the incidence of virus involvement of a variety of mouse tissues. These differences in mortality and in vivo growth of virus were not clearly mimicked in antiviral-antibody production in these different mouse populations.

ISSN:0008-4166    

DOI:10.1139/m78-002

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Several phytopathogenic fluorescentPseudomonasspecies, primarilyP.syringae, could be grouped into 16 bacteriocin producer groups, including new and previously described groups. At least 86% of theP.syringaestrains could be typed by bacteriocin production. There was poor correlation between bacteriocin type and host plant origin. No correlation was detected between syringomycin (a phytotoxin) production and bacteriocin type.

ISSN:0008-4166    

DOI:10.1139/m78-003

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Infectious pancreatic necrosis (IPN) virus was partially purified by freon extraction of infected CHSE-214 cells and concentrated by polyethylene glycol (PEG) precipitation of virus from the medium. Both methods resulted in virus concentrates that could be further purified by two CsCl gradient centrifugations with little loss of infectivity. A recovery of 80 to 100% of the virus infectivity was obtained and over 100-fold concentration of viral infectivity was achieved by these methods. This purification was used to compare 10 isolates of IPN virus with regard to their physiochemical properties by electron microscopy, buoyant density in CsCl, and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of the purified virions. Electron-microscopic observations showed that the virus isolates were identical in that they were isometric, hexagonal in profile, and had a particle diameter of 71 nm. The buoyant densities of the virus isolates in CsCl were found to be 1.33 g/ml. SDS-gel electrophoresis of the virus isolates revealed the presence of three polypeptides of molecular weight 50, 30, and 27 × 103daltons designated as VP50, VP30, and VP27, respectively.

ISSN:0008-4166    

DOI:10.1139/m78-004

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

When deprived of biotin,Arthrobacter globiformis425 exhibits abnormal morphology (large, branched forms of variable size) and a retardation of its normal growth rate. In chemostat cultures, when cells were grown under glucose limitation, the morphology was normal (coccoids or rods) at specific growth rates between 0.05 and 0.125 h−1(doubling times between 14 and 5.5 h, respectively) at 25 °C. The coccoid-to-rod morphogenesis occurs at a specific growth rate of 0.11 h−1. At the same specific growth rates and temperature, but under biotin limitation, abnormal morphology was observed.

ISSN:0008-4166    

DOI:10.1139/m78-005

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Leucosporidium stokesii, an obligately psychrophilic yeast, metabolizes glucose during the initial stages of aerobic growth by aerobic respiration. During later stages of growth and in the presence of excess glucose and limiting oxygen the organism develops a fermentative-type metabolism. Rates of respiration on the other hand remain relatively constant. The change in metabolism occurs only at temperatures which support growth of the organism and does not occur at 25 °C. Resting cells prepared from young glucose-grown cultures can be induced to ferment glucose. The induction process occurs only in the presence of glucose and is inhibited by actidione.

ISSN:0008-4166    

DOI:10.1139/m78-006

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The rate of fermentation of the rumen microflora was inhibited almost 30% by 5 μg/ml of arsenic added in the form of arsenite, although 304 μg/ml was required to cause 50% inhibition. Arsenate was less inhibitory. The rate of fermentation of a separated bacterial fraction was inhibited 37% by 1 μg of arsenite per millilitre, whereas 100 μg/ml had little effect on the fermentation of a separated protozoal fraction. Similar results were obtained for arsenate. Both fractions had the capacity to take up arsenate, but the protozoa took it up more readily to a higher intracellular concentration. Both arsenate and arsenite inhibited the growth of a number of rumen bacteria in pure culture at concentrations as low as 5 μg of arsenic per millilitre. The greater resistance ofMegasphaera elsdeniito arsenate as compared with that ofBacteroides succinogeneswas not related to the inability to take up the element.In conclusion, the concentrations of arsenic causing a significant inhibitory effect on the fermentative activity and growth of some rumen bacteria are less than that reported to be toxic to ruminant animals.

ISSN:0008-4166    

DOI:10.1139/m78-007

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The denitrifying capacity of 15 strains ofBacillus licheniformiswas evaluated. In general, N2production by the cultures on complex media containing NO3−is irregular and quite slow and three of the strains never produce gas.Bacillus licheniformisgrows rapidly in anaerobiosis on peptone medium containing NO3−which is reduced to NO2−. None of the strains grow in peptone medium with NO2−or N2O as the respiratory substrate, nor do they grow under an atmosphere of 10% NO–90% N2. Denitrification was studied in cell suspensions using gas chromatography. N2O production from NO3−or NO2−is always weak at best; nitric oxide is reduced to N2O at an appreciable rate. All the strains synthesize nitrate reductase A in anaerobiosis when NO3−is present. In cell extracts, nitrite reductase activity is always negligible or nil with tetramethyl-p-phenylenediamine as an electron donor.

ISSN:0008-4166    

DOI:10.1139/m78-008

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The stable L form ofAgromyces ramosusreverted to a bacterial form when incubated in sterilized soil. The cellular and colonial morphology of this bacterial form resembled that of the original parent bacterial form. The two forms differed, however, in that the revertant maintained its bacterial form when transferred onto a low-salt (NaCl) medium but was virtually completely induced into the L-form state on a high-salt medium. The original parent bacterial form was not sensitive to salt. The possibility is discussed that an L-form ↔ bacterial-form cycle for this bacterium might occur naturally in soil. This cycle would be mediated by fluctuations in local salt concentrations in the soil.

ISSN:0008-4166    

DOI:10.1139/m78-009

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The effect of temperature on the uptake systems involved with glucose catabolism was studied in a psychrotrophic strain ofPseudomonas fluorescens. TheKmvalues for glucose and gluconate uptake were approximately 1 and 30 μMrespectively whether uptake was assayed at 30 or 5 °C. TheKmfor 2-ketogluconate (2-KG) uptake was approximately 40 μMassayed at 30 °C and 20 μMassayed at 5 °C. Little or no induction of 2-KG uptake was detected in cells grown at 30 °C with glucose or gluconate. High induced levels of 2-KG uptake were observed in cells grown at 5 °C. The induced level of glucose uptake in cells grown at 5 °C with glucose was only one-half the induced level in cells grown at 30 °C with glucose (when activities were compared at the same assay temperature). The effect of low-assay temperature on the activities of these uptake systems was most pronounced for gluconate. When the assay temperature was decreased from 30 to 5 °C, uptake activity decreased 12-fold, 6-fold, and 5-fold for gluconate, glucose, and 2-KG, respectively. Because of the differential effect of temperature on the induction of glucose uptake and on the activity of glucose, gluconate, and 2-KG uptake, the major uptake activity measured in cells grown at 5 °C with glucose or gluconate was through 2-KG. Glucose and 2-KG appeared to inhibit significantly gluconate uptake and (or) catabolism which might promote the continued oxidation of gluconate to 2-KG at low growth temperatures. The results confirm the lack of glucose or gluconate catabolism by the direct oxidative non-phosphorylated pathway through 2-KG at higher growth temperatures and the major function of this pathway at lower growth temperatures.

ISSN:0008-4166    

DOI:10.1139/m78-010

出版商:NRC Research Press    

年代:1978

数据来源: NRC