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A new staining method for urease activity in non-denaturing polyacrylamide gels is described. The increase in local pH of the gel, resulting from ureolytic activity of urease, causes a purple red coloured band after incubation of the polyacrylamide gel with urea. Staining of urease activity using this method is very specific for catalytically active urease even in crude preparations. Detection of urease activity by this method is rapid, simple and economical. The described method is also more sensitive than existing methods of urease staining. A minimum of 0.25 mU of urease activity can be detected after 5 min of incubation with the substrate. The method has been used to demonstrate the presence of different charge isoforms of urease in a member of the plant family Cucurbitaceae. 相似文献
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Assay for soil urease activity 总被引:1,自引:0,他引:1
Summary A procedure is described that allows assay of soil urease activity. The method uses a phosphate buffer (pH 8.8) and a urea substrate concentration of 0.007 M. Incubation for 4 h at 37°C is recommended and urease activity is estimated by determining the amount of ammonium produced by urea hydrolysis in soil. The method is precise, and compares favourably with other procedures. re]19750710 相似文献
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A continuous method for the measurement of urease activity 总被引:2,自引:0,他引:2
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A R Cook 《Journal of general microbiology》1976,92(1):49-58
A strain of Streptococcus faecium from the sheep rumen showed spontaneous loss of urease activity when subcultured at the normal rumen temperature of 38 degrees C, although in mixed cultures in vivo or in vitro loss of urease was not apparent. The rate of loss of urease in pure cultures was increased at incubation temperatures above 38 degrees C, but loss was never complete. However, at temperatures below 38 degrees C loss was greater, and at 22 or 18 degrees C the urease was completely eliminated. Incubation with sodium dodecyl sulphate (0-002%) or ethidium bromide (2-5 X 10(-5)M) caused complete loss of urease activity. The urease activity was also eliminated when the streptococcus was grown aerobically, and this loss of activity was irreversible. It is suggested that the urease activity is controlled by a plasmid gene and that aeration, low growth temperature and chemical agents 'cure' the streptococcus of the plasmid. Attempts to demonstrate the presence of covalently closed circular extrachromosomal DNA by caesium chloride-ethidium bromide equilibrium density-gradient centrifugation were unsuccessful. 相似文献
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An effective selective medium for the enumeration of Aspergillus flavus and Aspergillus parasiticus has been developed by modification of Bothast and Fennell's Aspergillus Differential Medium. Results can be obtained with the new medium, Aspergillus flavus and parasiticus Agar (AFPA), after 42 h incubation at 30 degrees C. The medium is thus suitable for use in quality control as a guide to the presence of A. flavus and, potentially, of aflatoxins. AFPA has been extensively tested on peanuts and soils. Results were reproducible and comparable with those on standard fungal enumeration media incubated for much longer periods. A very low percentage of false positive or negatives was found. 相似文献
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An effective selective medium for the enumeration of Aspergillus flavus and Aspergillus parasiticus has been developed by modification of Bothast and Fennell's Aspergillus Differential Medium. Results can be obtained with the new medium, Aspergillus flavus and parasiticus Agar (AFPA), after 42 h incubation at 30°C. The medium is thus suitable for use in quality control as a guide to the presence of A. flavus and, potentially, of aflatoxins. AFPA has been extensively tested on peanuts and soils. Results were reproducible and comparable with those on standard fungal enumeration media incubated for much longer periods. A very low percentage of false positives or negatives was found. 相似文献
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An improved urease electrode 总被引:2,自引:0,他引:2
J G Montalvo 《Analytical biochemistry》1970,38(2):357-363
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The urease activity of fluorescent pseudomonads 总被引:9,自引:0,他引:9
D J Stewart 《Journal of general microbiology》1965,41(2):169-174
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We designed a new alkaline phosphatase (ALP)-sensitive fluorogenic probe in which a self-immolative spacer group, p-hydroxybenzyl alcohol, is linked to a profluorogenic compound to improve substrate specificity. Enzymatic hydrolysis converts the fluorogenic substrate 1 to a highly fluorescent reporter 3, thus allowing for the fast and quantitative analysis of ALP activity with greatly increased affinity for the enzyme. 相似文献
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A novel high throughput colorimetric urease activity assay was compared to the Nessler method. The new method employs phenol red to determine the urease activity. This method reduces significantly sample processing time and allows real-time investigations. This method is rapid, sensitive, easy, cost-effective, and does not use any toxic chemical reagents. 相似文献
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The ability ofYarrowia lipolytica to produce ammonia from urea was found variable on some media. The colour change of the indicator in Christensen's urea agar was not due to the urease activity of this species but was a non-specific alkalization reaction. Rapid urea broth was reliable giving no false positive results. It was found thatY. lipolytica is a urease negative yeast species. 相似文献
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农药对土壤脲酶活性的影响 总被引:10,自引:0,他引:10
通过模拟方法,研究了豆磺隆和呋喃丹对草甸棕壤和黑土6个土样脲酶活性的影响.结果表明,在供试浓度范围内,两种农药对土壤脲酶均有不同程度的激活作用,其中豆磺隆对草甸棕壤和黑土脲酶活性的最大增幅分别为46.95%和39.36%,呋喃丹分别为21.08%和12.70%.豆磺隆和呋喃丹浓度与土壤脲酶活性之间用二元一次方程拟和效果较好,分别有5个和3个土样的方程达到了显著或极显著相关水平,且二次项系数为负,总体上表现为先增加后降低的规律性变化.从两种农药对土壤脲酶的增幅和方程系数来看,豆磺隆对土壤脲酶活性的影响比呋喃丹明显. 相似文献