摘要:

A simple and reproducible micro tissue culture assay has been devised in RK13 and LLC-RK1 rabbit kidney cells for the titration and neutralization of rubella virus. In this "one-step" assay all virus and serum dilutions were prepared with spiral loops in disposable microplates and tissue cultures suspended in medium 199 and 3% horse or fetal calf serum were added to the microcups simultaneously. Micro tissue cultures were kept in a humidified incubator (36 °C) under a constant pressure of 5% CO2for 8 days and were read microscopically for viral cytopathic changes on the seventh and eighth day. The microneutralization test performed in LLC-RK1 cell cultures was shown to be a reliable method for the detection of small amounts of rubella antibodies in human sera.The micro assay may be also applied to the virus titration of live, attenuated rubella vaccines.

ISSN:0008-4166    

DOI:10.1139/m69-011

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Whole cells and cell-free extracts of the chemolithotroph,Ferrobacillus ferrooxidans, were used to investigate certain enzymatic reactions related to the glycolytic pathway and Krebs cycle measuring oxygen uptake manometrically; most glycolytic pathway and Krebs cycle intermediates when used as substrates were oxidized. With the use of specific enzyme assays, most of the enzymes of the glycolytic pathway and Krebs cycle were detected in crude cell-free extracts. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, enzymes of the hexose monophosphate pathway, were not found.

ISSN:0008-4166    

DOI:10.1139/m69-012

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A bacterium producing lytic enzymes was isolated from soil on bacterial agar in which heat-killed, Gram-negative cells served as a substrate. On the basis of its morphology, physiological properties, and growth characteristics, the lytic bacterium was identified as aPseudomonassp. It produced extracellular enzymes which were recovered from the culture nitrate by fractionation with ammonium sulfate and partially purified by ion-exchange chromatography on DEAE-cellulose. The enzymes which were resolved included a proteinase, at least two lipases, and one enzyme which caused some lysis of cell envelopes but was neither a proteinase nor lipase. Isolated envelopes of a Gram-negative bacterium,Chromobacterium violaceum, were extensively lysed by the enzyme mixture, and resulted in partial liberation of all the major envelope components, except phosphorus, in either a diffusible or non-diffusible form. In spite of large losses of protein, lipid, and polysaccharide, the enzyme-treated envelopes preserved their integrity and their elongated shape. This indicated that little or no hydrolysis of glycosaminopeptide took place.

ISSN:0008-4166    

DOI:10.1139/m69-013

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A strain ofBacillus pumiluswas isolated from Fargo clay in a field near Fargo, North Dakota, which had been cropped in flax 73 consecutive years. This bacterium had an unusual ability to survive saturated solutions of potassium cyanide. The optimal growth conditions of this strain ofBacillus pumilusin the standard medium with 10−1 Mcyanide as well as its morphological changes to a filamentous form under the influence of cyanide were established. Both14CO2and15NH4+were produced in cultures of the organism during labelling experiments in which K14C15N was fed, supporting the idea of cyanide utilization by this bacterium. Oxygen uptake studies by the filamentous form in the presence of 10−1 MKCN suggested that it has an extreme tolerance to cyanide. This is the first report of a bacterium being able to survive solutions of KCN up to 2.5 M.

ISSN:0008-4166    

DOI:10.1139/m69-014

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Rhizopus oligosporusNRRL 3271 produces an enzyme having high milk-clotting activity. High yields of the enzyme were noted in the culture filtrates of milk, wheat flour, or wheat bran. The enzyme was stable at 40 °C, or below, but its activity was destroyed rapidly by heating at 60 °C. The enzyme was fairly stable between pH 3 and 6 and very unstable at a pH below 2 or above 7. The enzyme was recovered from the culture filtrate by ammonium sulfate fractionation (30–75% saturation). When the enzyme preparation so obtained was chromatographed on a DEAE-cellulose column and eluted by salt gradient, four active components were noted, two of which accounted for most of the activity. The NRRL 3271 enzyme and animal rennin behave similarly toward the pH of milk, added calcium chloride, and sodium chloride. Although the NRRL 3271 enzyme caused a higher degree of proteolysis than did rennin, the proteolysis apparently was not high enough to interfere with curd formation. Therefore, the NRRL 3271 enzyme merits further study as a potential replacement for rennin or as an adjunct to be incorporated into rennin for the manufacture of cheese.

ISSN:0008-4166    

DOI:10.1139/m69-015

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

β-Galactosidase fromStreptococcus lactis7962 was partially purified and enzymatic and chemical properties were determined. The enzyme was unstable in phosphate buffer at 2 °C, dissociating into two forms and losing activity at the rate of 1.0% per hour. Dissociation was prevented and activity stabilized by treatment of enzyme extracts with 0.85 Mammonium sulfate. The two forms of the enzyme were separable by gel filtration on Sephadex G-200 equilibrated with buffer containing 0.85 Mammonium sulfate. These enzyme forms were indistinguishable on the basis ofKm(10−3 M), temperature (37.5 °C), and pH (7.05) optima. From molecular weight determinations of the two forms, it appeared that the form (dimer) having the larger molecular weight was composed of two monomers. Holding enzyme extracts at 27 °C for 22 h caused the dimer enzyme form to increase in amount while the monomer correspondingly decreased; ammonium sulfate stabilized cell extracts contained only the dimer form, suggesting that dissociation and reaggregation occurred in non-salt stabilized preparations. Culture age at the time of enzyme extraction also influenced the relative amounts of the two enzyme forms present; the dimer form decreased and monomer increased as the cells passed through the rapid growth phase; both forms of the enzyme decreased as growth slowed down.

ISSN:0008-4166    

DOI:10.1139/m69-016

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A stimulatory function of tryptophan was indicated in the synthesis of the purple pigment, violacein, in nine strains ofChromobacterium. In complex media, tryptophan increased the production of pigment, but the addition of glucose to a complex tryptophan medium supported considerably more pigmentation/cell mass. In a simple medium such as Koser citrate broth, tryptophan was essential for pigment production; however, pigment was produced in casein hydrolysate, indicating that other amino acids could replace the tryptophan requirement. Both mesophilic and psychrophilic strains were facultatively anaerobic in growth but required oxygen for pigmentation.

ISSN:0008-4166    

DOI:10.1139/m69-017

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Direct observation of washed macroconidia ofF.roseum'Sambucinum' infested in rewetted soil and incubated at 6 °C indicated that germination increased to 79% at 4 days and increased slowly thereafter. Lysis of germ tubes was inhibited and most germ tubes were not lysed even after 48 days incubation. Small two- or three-celled macroconidia were commonly produced on germ tubes. In contrast, peak germination (39%) occurred at 2 days in rewetted soil incubated at 25 °C with germ tube lysis occurring rapidly between 4 and 8 days. Only sparse sporulation was observed. After 9 months, survival ofF.roseum'Sambucinum' was much greater in soil incubated at 6 °C than at 25 °C.Macroconidia required an exogenous source of carbon for high germination and formed one- or two-celled chlamydosporic macroconidia in media lacking exogenous carbon. After 9 months incubation under carbon starvation conditions at 25 °C chlamydosporic macroconidia had a longer latent period and a much slower rate of germination than macroconidia. Germinated macroconidia formed two- or three-celled macroconidia within 24 h when transferred to media lacking exogenous carbon. Four-celled macroconidia were produced byF.roseum'Sambucinum' in a dilute glucose medium before exhaustion of the glucose whileF.solani'Coeruleum' formed chlamydospores in this medium after glucose depletion. Behavior ofF.roseum'Sambucinum' under carbon starvation conditions is similar to behavior in rewetted soil in the mode of sporulation and in the formation of chlamydosporic macroconidia, but differs by a lack of appreciable germination and by a greatly reduced lysis of fungal structures.

ISSN:0008-4166    

DOI:10.1139/m69-018

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Two different colonial types ofLeptospira semarangawere found to be oxidase positive, had the same spectrum of antibiotic sensitivities, and were similar antigenically. Both colony types were stable in vitro.

ISSN:0008-4166    

DOI:10.1139/m69-019

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Purified alpha toxin was cytotoxic to rabbit neutrophils as revealed by electron microscopy. Cells treated with alpha toxin showed aggregation of glycogen granules, extensive degranulation, and loss of cytoplasmic ground substance. Vesicles were present within the cytoplasm and outside the cells. The nuclear lobes were round and showed chromatin dissolution. Degranulation of the cell resulted in the formation of vesicles. These ultrastructural changes, except the nuclear changes, were similar to those of leucocytes treated with P-V leucocidin.

ISSN:0008-4166    

DOI:10.1139/m69-020

出版商:NRC Research Press    

年代:1969

数据来源: NRC