摘要:

Bacteroides gingivalisis a newly proposed species which includes strains isolated from the mouth. Thirteen strains ofB.gingivalisisolated from three geographic locations in the United States and France were examined with direct fluorescent antibody staining and analysis of total cellular fatty acids and compared with 16 strains ofB.asaccharolyticusof nonoral origin by the same methods.Bacteroides gingivalisstrains reacted with theB.gingivalisconjugate (fluorescein isothiocyanate labeled antibody reagent) only, while theB.asaccharolyticusstrains reacted with theB.asaccharolyticusconjugate only. TheB.gingivalisstrains showed negative fluorescence with fluorescein isothiocyanate conjugates for other black-pigmentedBacteroidesspecies. The specificity of theB.gingivalisconjugate was demonstrated by its failure to stain 88 strains of aerobic and anaerobic bacteria other thanB.gingivalis. The fatty acid profiles ofB.gingivalisandB.asaccharolyticuswere readily distinguishable. TheB.gingivalisprofile was also distinguishable from those of other pigmentingBacteroidesspecies on the basis of concentration ratios among the characteristic components. These results support the species separation ofB.gingivalisandB.asaccharolyticus. Further, they indicate the usefulness of cellular fatty acid profiles as an adjunct to the use of specific fluorescent antibody conjugates for identification ofBacteroidesspecies.

ISSN:0008-4166    

DOI:10.1139/m82-056

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The surface ofPropionibacterium acnes, VPI 0009, was studied using microelectrophoresis following chemical treatments intended to modify specific charged groups. The effect of these specific chemical modifications on ability of cells to induce splenomegaly, an indicator of stimulation of the reticuloendothelial system, was also determined. There was little difference between pH mobility curves ofP.acnesVPI 0009 and other strains of propionibacteria which were not able to stimulate the reticuloendothelial system. Amino and carboxyl groups were found to be the sole ionizable groups at the cell surface and modification of these groups caused a substantial decrease in the ability of cells to stimulate the reticuloendothelial system. No phosphate groups were detected. Evidence for two types of amino groups was found: one type was present on protein moieties and their modification did not affect ability to stimulate the reticuloendothelial system, whereas modification of the other type, which was present on carbohydrate moieties, caused a loss of ability to stimulate the reticuloendothelial system. Mild oxidation with sodium metaperiodate caused abolition of reticuloendothelial system stimulation, but had no effect on surface charged groups, indicating it was acting on the unsubstituted linkages of sugar residues. Treatments with strong acids caused abolition of ability to stimulate the reticuloendothelial system and this was accompanied by release of polysaccharide material.

ISSN:0008-4166    

DOI:10.1139/m82-057

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Compared with growth on citrate, growth ofPseudomonasC12B with acetate as a carbon source resulted in approximately a four- to six-fold reduction in arylsulfatase activity irrespective of the sulfur source utilized to derepress arylsulfatase formation. Similarly, whenO-acetyl-L-serine, oxaloacetate, malate, or α-ketoglutarate served as carbon sources in place of acetate, a reduction in arylsulfatase levels also occurred to varying degrees Trivial explanations for these results have been ruled out but efforts to provide an explanation for the inhibitory effect of acetate were unsuccessful. Some evidence suggests that growth on acetate may generate the formation of a substance which inactivates or irreversibly inhibits the enzyme.

ISSN:0008-4166    

DOI:10.1139/m82-058

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Competence development in nitrogen-fixingAzotobacter vinelandiicells was optimal at pH 7.2–7.4 which necessitated additional buffering of the iron-limited nitrogen-free competence medium or the addition of a suitable organic acid salt, e.g., sodium acetate. An autolysin was active in this pH range and competent cells were more susceptible to autolysis than the general cell population. Competence development also required restricted aeration of the culture, and only those cultures that attained zero dissolved oxygen became competent. Restricted aeration served to protect the iron-limited cell nitrogenase from oxygen inactivation thus allowing the culture to reach zero dissolved oxygen. The inclusion of additional sources of reductant, e.g., malate, in buffered competence medium resulted in increased respiration and protection of nitrogenase, increased cell mass, and poly-β-hydroxybutyrate synthesis, but decreased competence. A possible explanation for the apparent competition between competence development and nitrogenase activity is discussed.

ISSN:0008-4166    

DOI:10.1139/m82-059

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Bluegill virus (BGV) grown in BF-2 cells was studied by negative staining and ultrathin sections of infected cells. Although BGV resembles bunyaviruses in gross physical appearance, it differs from this group in several important aspects. Thus, BGV cannot be classified as a member of the Bunyaviridae family and could be a representative of a novel family of enveloped RNA viruses.

ISSN:0008-4166    

DOI:10.1139/m82-060

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A serological survey showed antibodies toFrancisella tularensispresent in 1.55% of snowshoe hares (Lepus americanus struthopus) and 1.06% of moose (Alces alces americanaClinton) sampled in Nova Scotia. No antibody-positive hares were found in Prince Edward Island, however. We believe this to be the first report of antibodies toF.tularensisin the moose.

ISSN:0008-4166    

DOI:10.1139/m82-061

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The 16 biotypes of theCryptococcus vishniaciicomplex of anamorphic yeasts (Basidioblastomycetes), unique to the Dry Valleys of Antarctica, include seven species separated by DNA–DNA homologies of less than 52%. Since species belonging to the complex can be as distantly related asC.bhutanensis(a Himalayan yeast, guanine + cytosine (G + C) 54.18 mol%) is to these species, a common ancestor probably originated and speciated outside of the Dry Valleys. The speciesC.vishniacii(G + C 54.52–55.48 mol%) comprises seven varieties with greater than 59% DNA–DNA homology and must therefore have been established in the Dry Valleys long enough to have evolved these divergent genomes. In theC.vishniaciicomplex, G + C values differing by more than 1 mol% are accompanied by DNA–DNA homologies of less than 23%.

ISSN:0008-4166    

DOI:10.1139/m82-062

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Eighteen gram-negative marine bacteria and two terrestrial species,Escherichia coliandPseudomonas aeruginosa, were examined for their sensitivity to lysis in distilled water after exposure either to a salt solution containing a sea water concentration of Mg2+(0.05 M) or to 0.5 MNaCl. A spectrum of lytic susceptibility was observed among the marine bacteria ranging from those organisms which lysed in distilled water after exposure to the Mg2+-containing solution, through organisms which could be sensitized to lysis by washing with the NaCl solution, to organisms which failed to lyse in distilled water even after having been washed with a solution of 0.5 MNaCl.Pseudomonas aeruginosaandE.colifell within this spectrum, the former being capable of being induced to lyse in distilled water by washing with 0.5 MNaCl, while the latter failed to lyse in distilled water after this treatment. It was thus concluded that no overall distinction could be made between marine and terrestrial bacteria on the basis of the sensitivity of the two groups of organisms to lysis in freshwater.Quite large decreases in optical density and increases in the release of ultraviolet-absorbing material took place when cells preexposed to the Mg2+-containing solution or to 0.5 MNaCl were subsequently suspended in distilled water even though in some cases no loss of cell numbers could be detected. In most cases two to three times as much K+as Na+and 1/10 to 1/100 as much Mg2+was required to prevent these changes. For three of the marine bacteria andP.aeruginosagrown in a terrestrial type medium little difference in the requirements for Na+and K+to prevent the optical density changes was noted. ForP.aeruginosagrown in a marine type medium, cells required more K+than Na+to prevent these changes.

ISSN:0008-4166    

DOI:10.1139/m82-063

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

In an approach to characterizing the nature of the lethal event in thymineless death (TLD),recmutants ofEscherichia coliK12 were examined for their sensitivity to TLD. TherecB21andrecC22mutations sensitized cells of the AB1157 line to TLD but not cells of the HF4733 line. This increased sensitivity was not suppressed substantially by eithersbcB15orxonA1mutation. In contrast, arecFmutation appeared to make cells more resistant to TLD thanrec+cells. Three differentrecAalleles were shown not to affect TLD appreciably. These results not only provide further support for the view that the site of the lethal event in TLD is cellular DNA, but also strongly suggest the involvement of therecBCandrecFgene products in TLD. The apparent indifference ofrecAmutation implies that the conventional recombination and repair pathwaysper seare not involved in TLD and that the hypothetical lethal damage to DNA may be unique in nature.

ISSN:0008-4166    

DOI:10.1139/m82-064

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The mechanism by whichChaetomium globosum, applied as ascospores to squash, snap bean, and pea seeds, reduces damage caused by larvae of the seed-corn maggot,Hylemya platura(Meigen), and soilborne plant pathogens was investigated.Chaetomium globosumascospores germinate rapidly and cover the seed coat with a dense mat of mycelium soon after seeds are planted in soil. However, if seeds are not treated withC.globosumbefore planting, other organisms rapidly colonize the seed coat during germination. Seed flies oviposit near seeds in response to the growth of pseudomonads on the seed surface. Studies employing a selective medium indicate thatPseudomonasbecome the most prevalent genus occurring on the seed coat during seed germination. Treatment of seed withC.globosumsuppresses the logarithmic growth of pseudomonads on the seed coat but affects neither bacterial populations in the soil surrounding the seed nor germination ofFusarium solanif. sp.pisichlamydospores, either on the seed coat or in the soil surrounding the seed. A water-insoluble antibiotic was extracted fromC.globosumtreated seeds. After systemtic examination of other possibilities, it was concluded that this nondiffusable antibiotic substance produced byC.globosumsuppresses pseudomonads responsible for stimulation of oviposition by seed flies as well as the soilborne plant pathogens.

ISSN:0008-4166    

DOI:10.1139/m82-065

出版商:NRC Research Press    

年代:1982

数据来源: NRC