摘要:

Fifty-five soil samples, from 21 geographic locations in seven countries, from whichHistoplasma capsulatumwas isolated were analyzed mineralogically by X-ray diffraction techniques. None of the soils, excepting two from a site from Italy, contained swelling, three-layer clay minerals that expanded beyond 14 Å when homoionic to K, air-dried, and saturated with glycerol. Presence of the fungus was not related to the presence or absence of other clay mineral species or to soil pH. These results were similar to those obtained withFusariumwilt of banana, in that rate of spread of the wilt was rapid in soils not containing such swelling three-layer silicates but was slow in soils that contained them. These observations, together with those demonstrating that various clay minerals differentially influence growth and activity of bacteria and fungi, suggest that the distribution in soil of this human pathogen is influenced by the type of clay minerals present.

ISSN:0008-4166    

DOI:10.1139/m67-001

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A lesion-inducing factor (LIF) of virulent avian strains ofEscherichia coliwas investigated. Liver lesions were produced by concentrated dialyzed filtrates of broth cultures grown at 37 C in a synthetic medium. LIF activity was present in washed cell walls and in extracts from intact cells prepared by a procedure using 1 MNaCl. Extraction with 5 × 10−3 MEDTA alone or in combination with 1 MNaCl also resulted in preparations with satisfactory LIF activity. Preparations obtained by hot water or phenol–water extraction possessed less LIF activity on a weight basis. LIF activity was shown in extracts from three different serogroups ofE.coli.

ISSN:0008-4166    

DOI:10.1139/m67-002

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Bacillus cereus, strain TS, was grown in 30-liter stirred fermentors on a complex medium. Pigment was isolated from the cells and converted to the free acid, which was identified as pulcherriminic acid. A procedure for the spectrophotometric assay at 410 mμ of pulcherrimin and pulcherriminic acid was developed to measure the maximum, but not necessarily absolute, degree of purity of samples of these compounds.

ISSN:0008-4166    

DOI:10.1139/m67-003

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A number ofSalmonellaspecies are capable of fractionating sulfur isotopes during sulfite reduction under aerobic and anaerobic conditions. The product H2S may be enriched in32S by over 3% as compared to the initial sulfite32S/34S composition. This is significantly higher than the isotope effect realized in the equivalent inorganic chemical reduction.

ISSN:0008-4166    

DOI:10.1139/m67-004

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

A direct relationship between rose bengal concentration, light intensity, and the inhibition of linear growth ofAspergillus nigerwas demonstrated. Exposure of the fungus to a light intensity of 100 foot-candles for not more than 30 seconds daily was sufficient to cause inhibition of growth when the culture medium contained rose bengal in a concentration of 2 × 10−3 M. Rose bengal alone, in total darkness, apparently does not inhibit the growth ofA.niger. There appears to be a relation between the presence of rose bengal and light and the sporulation ofA.niger.

ISSN:0008-4166    

DOI:10.1139/m67-005

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Cells ofEscherichia coliK12 (λ +) andEscherichia coliM3 (λ59) were desiccated at various levels of relative humidity (R.H.). When the cells were cultured in an enriched medium and held at 55% R.H., induction of the prophage in 36% ofE.coliK12 cells and 75% ofE.coliM3 cells occurred. At 30% R.H. or 70% R.H., fewer inductions took place. The maximum number of cells in which prophage induction occurred was found 15 minutes after desiccation began withE.coliK12 and immediately after the cells were dried withE.coliM3. After the attainment of maximum levels of induction, plaque-forming ability was gradually destroyed, but the rate of destruction was dependent on the R.H. at which the cells were held. The plaque-forming ability of the free viruses and of cells in which prophage induction had occurred were destroyed by prolonged desiccation at different rates. Also, the loss of colony-forming ability of the cells was more rapid than the inactivation of plaque-forming ability of either induced prophages or the free viruses. The compound,i-inositol, prevented prophage induction by desiccation and also stopped the destruction of induced prophages within the cell.It is concluded that water molecules bound to the DNA hold the prophage to the host DNA and their removal results in induction.

ISSN:0008-4166    

DOI:10.1139/m67-006

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Non-growing cells of a psychrophilic marine bacterium lyse if subjected to temperatures above 21 °C, to low ionic strengths, or to pH values below 6.0. Microelectrophoretic techniques were used to help determine the surface effects of cellular breakdown. During lysis, however induced, the cell populations became heterogeneous in mobility. This was apparently due to the adsorption of intracellular material, with a higher negative charge than intact cells, onto the cell surface. The mobilities of cells lysed in water or at acid pH reverted to the control values after repeated washings, which were thought to remove adsorbed intracellular material. Lysis induced by these latter treatments, therefore, did not involve the external cell surface. Water-lysed cells were stable at temperatures where both whole cells and mechanically prepared cell envelopes were subject to breakdown. After temperature-induced lysis, the washed cells possessed a higher negative mobility than intact cells, which was not due to the presence of adsorbed intracellular material, but rather to an irreversible surface change. Lysis in distilled water at 25 °C left the cell surface unchanged, and the "temperature effect" of a permanently increased negative charge was only evident when lysis at 25 °C preceded exposure to distilled water.

ISSN:0008-4166    

DOI:10.1139/m67-007

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The deoxyribonucleic acid (DNA) from cells ofEscherichia coliB, after rigorous extraction, was found to contain residual amounts of protein, the quantity of which was determined by the medium in which the cells were grown. The DNA of cells grown in a minimal salts medium contained from 10 to 15 times more protein than the DNA of cells grown in an enriched medium. The addition of amino acids, vitamins, or nucleic acid bases to the growth medium resulted in a decrease in the amount of residual protein and an increase in the sensitivity of the cells to ultraviolet light. Of the enrichments tested, the amino acids produced the greatest decrease in the quantity of residual proteins and the largest increase in sensitivity to ultraviolet. The type of mutant cell produced by ultraviolet irradiation was found to be strongly influenced by the ingredients of the growth medium. Few mutants were found after the irradiation of cells grown in the minimal salts medium but when the growth medium was enriched with amino acids, many mutants requiring amino acids appeared. Similarly the addition of vitamins or bases resulted in the production of vitamin-and base-requiring mutants. It is suggested that these residual proteins become attached to specific sites on the DNA during the operation of certain genes and this results in an increase in the ability of the DNA to withstand the damaging action of desiccation and ultraviolet light.

ISSN:0008-4166    

DOI:10.1139/m67-008

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The irradiation ofEscherichia coliB with sublethal doses of 3000–4000 Å light prevented the microorganisms from manufacturing β-galactosidase and T2 and T7 coliphages. Inhibition occurred only if the cells were irradiated immediately after their contact with the inducer lactose or infection with T2 and T7 phages. If, before irradiation the cells were allowed to incubate for 15 min after the addition of lactose or the coliphages to the cells, little effect of the light was found. The uptake of uracil and amino acids by washed cells was more rapid in the first 15 min than during later time periods while thymine uptake did not begin until the first 15 min had elapsed. The 3000–4000 Å light inhibited the uptake of arginine and thymine but not uracil or glutamic acid. The addition of 5% inositol inhibited the synthesis of β-galactosidase and the uptake of14C-labelled metabolites. Since there was a strong correlation between the degree to which arginine and thymine uptakes were inhibited by the light or inositol, it appears that the production of a protein during the first 15 min is intimately connected with DNA replication and the synthesis of induced enzymes.

ISSN:0008-4166    

DOI:10.1139/m67-009

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

This study is concerned with the effects of aluminium, arsenic, boron, cobalt, copper, fluorine, iron, iodine, lithium, magnesium, molybdenum, and zinc onBacillus thuringiensisvar.thuringiensisBerliner. Addition of small quantities of the elements to the culture medium stimulated growth of theBacillus. The effect was particularly marked during cell division, as revealed by an increase in area of the clones. The toxic effects of certain concentrations of the elements was also revealed during cell division, which, as indicated by the clonal area, was adversely affected by B, Cu, I, Mg, and Zn. F, Fe, Li, and Mo effected retardation of the cell division by as much as 12 to 48 hours. Al, As, Cu, and Mg both retarded and reduced cell division. By determining the relation between the effective limiting doses established, we were able to divide the elements into four groups. The toxicity of the elements was also revealed by its effects on the germination of the spores, clonal structure, form of the cells, time of sporulation, synthesis of the toxin-crystal, and cellular lysis.

ISSN:0008-4166    

DOI:10.1139/m67-010

出版商:NRC Research Press    

年代:1967

数据来源: NRC