摘要:

Greenhouse and plant growth room experiments showed that shading of plants had no appreciable effect on the vegetatively active fungi colonizing the primary roots of wheat and soybean seedlings growing in fertile, disease-free soil. Although marked differences in plant development were obvious, the general pattern of root colonization was essentially the same for the two levels of illumination used. The results suggest that the saprophytic fungi which normally colonize the roots of healthy plants may also colonize roots of abnormal plants providing that the soil is relatively free from plant pathogenic forms.Species ofPhomaaccounted for a much higher proportion of the isolates from wheat roots than from soybean roots, whereas the majority of cultures from soybeans proved to be species ofFusarium.

ISSN:0008-4166    

DOI:10.1139/m61-001

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The occurrence of aerobic, non-symbiotic, nitrogen-fixing bacteria was determined in samples of soil collected in the various soil zones of Alberta and Saskatchewan. Mannitol and sodium benzoate dust-plates, and mannitol solution cultures with subsequent inoculation onto mannitol agar demonstrated thatAzotobacterwere not widespread in the Canadian prairie province soils. These procedures also led to the isolation of smaller, aerobic, non-symbiotic, nitrogen-fixing organisms from all the Alberta and Saskatchewan soils studied. These smaller, nitrogen-fixing bacteria which developed as 1- to 3-mm circular, convex, unpigmented colonies on mannitol and glucose agar were classified asPseudomonas. Flagellation of the 0.75 to 1 μ by 1.5- to 2-μ Gram-negative, coccoid rods was polar. Starch was hydrolyzed; gelatin was not liquified. Indol, acid, and gas were not produced; litmus milk was not reduced, but hydrogen sulphide was formed. The pseudomonads, capable of initiating growth at a pH of 4.9, could also grow at 8 °C, whereas theAzotobacter chroococcumrequired higher temperatures and reactions above pH 6.2.Azotobacter chroococcumfixed up to 12 mg nitrogen per gram of carbohydrate. The smaller bacteria, classified asPseudomonas azotogensis, fixed from 0.1 to 3.9 mg N per gram of mannitol.

ISSN:0008-4166    

DOI:10.1139/m61-002

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Phytophthora cryptogea, cause of a root disease of alfalfa, grew well over a wide range of pH values (5.6–7.2) on a synthetic medium containing sucrose as the carbon source. The fungus also grew well on glucose and soluble starch.L-Asparagine was the most favorable source of nitrogen, but failed to support growth of a variant obtained from a single germinated oospore. Low concentrations of CaCl2∙2H2O stimulated growth ofP.cryptogea,P.drcehsleri,P.parasitica, andP.boehmeriae. The minimal concentration of thiamine for growth was between 12 and 25 μg/liter. Soil extract, representing 50% or 90% of the volume of the synthetic medium, did not supply the thiamine requirement or stimulate growth of the fungus. Alfalfa root extract, alone or added to the synthetic medium, not only satisfied the thiamine requirement of the fungus but produced about 30% more mycelial growth than the complete synthetic mediu

ISSN:0008-4166    

DOI:10.1139/m61-003

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A chemically defined medium for growth ofM.lysodeikticusis presented. The organism possesses a relatively nonspecific but absolute purine requirement that can best be satisfied by the free base hypoxanthine although adenine also allows some growth. A substitution for hypoxanthine, however, can be made by inosine, adenosine, or adenylic acid, but not by guanosine or guanylic acid. Although biotin stimulates growth, equally good growth occurs using biocytin or biotiu-d-sulphoxide. Less stimulation is apparent using desthiobiotin,dl-oxybiotin, or biotirt-l-sulphoxide. Although amino acids are necessary for growth, no absolute requirement for a specific amino acid can be demonstrated. The amino acid requirements need to be defined in terms of those amino acids which support good growth in the presence or absence of glutamic acid.

ISSN:0008-4166    

DOI:10.1139/m61-004

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A synthetic medium containing 0.4% rutin, 0.3% (NH4)2HPO4, 0.1% KH2PO4, 0.1% MgCl2∙6H2O, and 0.8% (NH4)2SO4was developed for the production of the extracellular enzyme system that degrades rutin. The total amount of the enzyme system produced is approximately the same between 25 and 35 °C but the rate is more rapid at the higher temperature. Aeration is necessary both for synthesis and for excretion into the medium, excretion apparently being more sensitive than synthesis. Magnesium is required for growth and sulphate for release of the enzyme system into the medium. Calcium carbonate depresses both growth and production. The medium has been successfully employed for production in 5-gallon fermentors of the extracellular enzymes that degrade ruti

ISSN:0008-4166    

DOI:10.1139/m61-005

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The preparation of staphylococcal intracellular penicillinase as a cell-free concentrate is described and the optimal conditions for its action on penicillin indicated. Cells were disrupted by sonic vibrations and the debris removed by centrifugation at 17000 × g. Cell-free concentrates were prepared from the supernatants and were found to have a higher activity per mg nitrogen than the bacterial suspensions from which they were prepared. Centrifugation at 35000 × gresulted in a partial and as yet unaccountable loss of activity. The enzyme was optimally active at pH 6.0–6.5 and 30 °C. The possible application of cell-free staphylococcal penicillinase to enzymatic and immunological work is discussed.

ISSN:0008-4166    

DOI:10.1139/m61-006

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A partially purified intracellular enzyme from a species ofAlcaligenesis described which specifically initiates the degradation of the he heteropolysaccharide ofCryptococcus neoformans, isolate 3723, The enzyme is active in the presence of serum and can be inactivated by heating at 45 °C for 10 minutes, The kinetics of the enzyme reaction are similar to those of other enzymes. Recovery and identification of the four known monosaccharides from enzymatic hydrolyzates suggest the presence of a number of other enzymes in these preparations.

ISSN:0008-4166    

DOI:10.1139/m61-007

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A particulate preparation from extracts ofAerobacter aerogenesoxidized 2-deoxy-D-glucose to 2-deoxy-D-gluconate, 6-deoxy-6-fluoro-D-glucose to 6-deoxy-6-fluoro-2-keto-D-gluconate, andD- andL-lactate to pyruvate.The oxidations ofD-gluconate andD- andL-lactate were found to be different with regard to pH of optimum activity, and to various inhibitory compounds. On the basis of these and other observations, it is suggested that the three substrates were oxidized by different enzyme systems. Other results suggest that the oxidation reactions were catalyzed by flavoprotein enzymes.

ISSN:0008-4166    

DOI:10.1139/m61-008

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Diethylstilbestrol readily inhibits the reduction of triphosphopyridine nucleotide by a glucose-6-phosphate dehydrogenase prepared from fractionated cell-free extracts ofAerobacter aerogenes. Hexestrol and dienestrol exert a similar influence but the dehydrogenase system was not sensitive to a number of steroids. The degree and extent of inhibition was a function of the diethylstilbestrol concentration. The inhibition could not be reversed by the addition of excess glucose-6-phosphate or triphosphopyridine nucleotide but the suppression could be relieved by the addition of increments of the fractionated extract containing the glucose-6-phosphate dehydrogenase enzyme. Several other enzymes such as isocitrate, alcohol, and malate dehydrogenases were found to be present in the same fraction but reduction of nucleotides by these enzymes was not influenced by the steroids or synthetic estrogen. A tentative hypothesis is that diethylstilbestrol may interact directly with certain enzymes, under specified experimental conditions, thereby regulating the rate of the enzymatic reaction. These findings thus suggest yet another mechanism whereby a synthetic estrogen may regulate intermediary metabolism.

ISSN:0008-4166    

DOI:10.1139/m61-009

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

When heterotrophically grownRhodospirillum rubrumwas reincubated anaerobically in the light, the photosynthetic growth resulted in a simultaneous appearance of the photosynthetic pigments, photooxidation, and photophosphorylation. Addition of exogenous diphosphopyridine nucleotide to extracts of photosynthetically grown cells inhibited photooxidation while photophosphorylation was stimulated. Ultraviolet irradiation inhibited photophosphorylation and added menadione relieved the inhibition. Photooxidase was less inhibited by this irradiation and menadione had no effect. No direct relationship between photooxidation and photophosphorylation could be shown.

ISSN:0008-4166    

DOI:10.1139/m61-010

出版商:NRC Research Press    

年代:1961

数据来源: NRC