摘要:

Cells ofM.halodentitrificansgrown in 1.0 MNaCl contained 11 ± 2% total lipids, of which about half was phosphatide. Seven lipid components were detected by chromatography, two of which were tentatively identified as phosphatidyl ethanolamine and phosphatidyl glycerol; lecithin was completely absent. No qualitative changes were found in the phospholipid or fatty acid constituents of cells grown in media containing different concentrations of sodium chloride, but cells grown in low salt concentration (0.6 Mand 0.55 M) contained 7 to 10 times more unsaponifiable matter than cells grown at the optimal salt concentration (1.0 M). However, the addition of calcium, magnesium, or potassium to low-salt media restored the amount of unsaponifiable matter in cells to normal.

ISSN:0008-4166    

DOI:10.1139/m61-052

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The occurrence ofAzotobacterin the rhizosphere of 17 crop plants grown in different types of soil in the field and in the greenhouse has been studied as part of a program of work on the interaction of plants and free-living nitrogen-fixing microorganisms.Azotobactercounts were very low in both rhizosphere and non-rhizosphere soil from the field; they varied with the type and age of the plant and with the type of soil. The organism was usually absent from acidic and poor soils. I n the greenhouse experiments, soil counts of these bacteria were found to be somewhat higher than in the corresponding soil in the field (Granby sandy loam). The root effect was greater with both radish and wheat in the poor soil (Upland sand) than in the fertile Granby soil. Onion exerted no obvious influence on theAzotobacterpopulation in either soil. However, even under optimum conditions of plant growth, numbers of these organisms were very low in comparison with those of other bacteria normally present in soil and in the root zone.

ISSN:0008-4166    

DOI:10.1139/m61-053

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Recirculation of oxygen during submerged citric acid fermentation of ferrocyanide-treated beet molasses byAspergillus nigerwas successful. Results obtained in 36-liter glass tower fermenters showed that neither rate of production nor total yield of citric acid was affected. No treatment of the recirculated gas other than carbon dioxide removal was required. At both low and high oxygen flow rates, increased oxygen pressure (up to 1.7 atm) markedly increased initial rate of production and total yield of citric acid. Oxygen pressure above 1.7 atm decreased citric acid yield. Within the limits tested, the effect of oxygen pressure was independent of total pressure.

ISSN:0008-4166    

DOI:10.1139/m61-054

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A phage-like particle (phage i) found in filtrates ofRhizobium trifolii(strain RT 9) did not produce plaques but induced development of two different phages in a presumed defective lysogenic strain (RT 10). These induced phages (phages 9 and 10) differed in their host ranges and produced plaques on strains RT 9 and RT 10, respectively. Phages 9 and 10 were closely related serologically and were distinct from phage i. Although ultraviolet irradiation resulted in the lysis of RT 10, no free phage was detectable in such lysates. Phage i particles had morphological, chemical, and physical properties similar to those of functionalRhizobiumphages but did not produce plaques on any of 12R.trifoliistrains tested. Development of phage i could be induced with ultraviolet irradiation or by treatment with mitomycin C.

ISSN:0008-4166    

DOI:10.1139/m61-055

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

This paper deals with a study of the antigenic properties of influenza strains adapted to tissue cultures. When adapted to chick embryonic tissue, influenza strains lose most of their antigenicity; when adapted to monkey kidney cultures under the same conditions, influenza strains maintain their antigenic value to a high level.

ISSN:0008-4166    

DOI:10.1139/m61-056

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Antigenic analyses of extracts ofTrichinella spiralislarvae were done using Immunoelectrophoresis as the principal analytical method. Eleven electrophoretically distinct antigens were identified in buffered saline extracts. Different numbers of antigens (but not more than 11) were found in other preparations, but these gave reactions of complete immunological identity with antigens in the saline extract.

ISSN:0008-4166    

DOI:10.1139/m61-057

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The red halophiles,Halobacterium salinarium,H.cutirubrum,H.halobium, andSarcina litoralis, grew most rapidly at salt concentrations of 20–25% and temperatures of 40–45 °C. Maximum turbidity was obtained at similar salt concentrations but at 35–40 °C. An unidentified colorless rod grew most rapidly at salt concentrations of 17.5–20% and temperatures of 40–50 °C, but produced maximum yield at 30 °C. The rod forms changed from long slender rods through irregular shapes to spheres as the salt concentration was decreased. At temperatures above the optimum, cells were very irregular, but otherwise temperature at any one salt concentration had little or no effect on the morphology.

ISSN:0008-4166    

DOI:10.1139/m61-058

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

An apparatus is described for the continuous growth of bacteria.Brucella abortusS.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

ISSN:0008-4166    

DOI:10.1139/m61-059

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

This study represents an attempt to correlate the low numbers ofAzotobacterin rhizosphere and root-free soils at the Central Experimental Farm, Ottawa, with the incidence of bacterial and actinomycete antagonists of this organism. Wheat, radish, and onion were grown in the greenhouse in two soils varying greatly in fertility and organic matter content, and isolations of bacteria and actinomycetes were made periodically for testing againstAzotobacter. It was found that rhizosphere soil contained greater numbers of microorganisms antagonistic toAzotobacterthan root-free soil. Of the three crops used wheat exerted the least effect. In all the tests numbers of antagonists were greater in the fertile Granby sandy loam than in the infertile Upland sand. The results correlated well with theAzotobacterpopulations in these soils as reported in the first paper of this series.

ISSN:0008-4166    

DOI:10.1139/m61-060

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The pyruvic dehydrogenase system ofClostridium pasteurianumhas been shown to catalyze a multistep reaction. Spectrophotometric experiments with aged and dialyzed preparations have implicated flavin, the hydrogenase system, and iron in this reaction. Molybdenum, which is not required for the normal action of the hydrogenase system, is needed in some form for the reduction of one-electron acceptors. The carbon monoxide combining component of this system is not of the hemochromogen type and must be in the reduced state before combining with carbon monoxide. A scheme is presented for the liberation of hydrogen from pyruvate by cell-free extracts in the presence of methyl viologen.

ISSN:0008-4166    

DOI:10.1139/m61-061

出版商:NRC Research Press    

年代:1961

数据来源: NRC