• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1063-1069
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• 1999

Wheat straw samples (3-4 cm) were sprayed with solutions of urea (U) alone or with a dry addition of garden soil (GS), midden soil (MS), soya bean meal (SM) or jack bean meal (JM) as crude urease sources and with a pure urease (UR) enzyme. Each of the urease sources was included at two levels: 30 and 60 g/kg except pure urease, which was added at a level of 2.5 & 5.0 g/kg treated straw dry matter. Untreated straw without urease source was used as a control. After treatment, samples were sealed in polythene bags and stored for 2, 7, 14, 21 and 35 days at $19{^{\circ}C}$. The urease sources, their levels and treatment time produced significant effects on ammonia production (p<0.01). The addition of urease offered more flexibility in hydrolyzing urea in the shortest possible time. Incorporation of soya bean and jack bean meal was effective in reducing the modified acid detergent fiber (MADF) content of straw and the same time increasing organic matter (OM) digestibility. Overall effect, addition of soya bean to urea at a ratio of 1:1 appeared to be the most satisfactory urease source for the treatment of urea and wheat straw.

• Journal of Life Science
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• v.17 no.4 s.84
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• pp.581-586
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• 2007

Staphylococcus epidermidis is a coagulase-negative, gram-positive bacterium that normally inhabits the human skin. S. epidermidis is also known to be an opportunistic pathogen in infections of various indwelling medical devices. This report describes purification and characterization of the urease of S. epidermidis urease, which may act as a virulence factor. The urease from S. epidermidis was purified 1,127 fold by using DEAE-Sepharose, Phenyl-Sepharose, Mono-Q and Superdex HR200 column chromatography. The specific activity of the purified enzyme was 993.8 U/mg. Michaelis constant($K_m$) of the enzyme was estimated to be 8.5 mM urea by using Lineweaver-Burke double reciprocal plot. The native molecular weight of the urease was shown to be 255 kD by using Superose 6HR gel filtration chromatography and the purified enzyme contained 2.2 nickel ions per catalytic unit. The overall stoichiometry of the enzyme subunits appears to be $(\alpha\beta\gamma)_3$, which is consistent with the enzymes from other bacteria sources.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.1
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• pp.14-20
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• 2009

Classification of land uses and analysis of nitrogen isotope fractionation in groundwater nitrate were carried out to examine its contamination sources in Jeju province. ${\delta}^{15}N$ values of urea (hydrolyzed with urease), ammonium sulfate, compost, water from septic tank were -1.7, -5.8, +14.1, and +24.0‰, respectively. Urea, when it was directly distillated, showed -16.5‰. Based on these ${\delta}^{15}N$ values, sources of nitrate could be classified as originated from chemical fertilizers with ${\delta}^{15}N$ values below +5‰ and as from animal manure or municipal waste with ${\delta}^{15}N$ values over +10‰. Results of ${\delta}^{15}N$ analysis of 33 wells showed that most wells had the chemical fertilizers as their dominant contamination source. However, some wells were contaminated by other sources: animal wastes or municipal wastes. Some wells were also contaminated by the combined sources of nitrate. It was also demonstrated that ${\delta}^{15}N$ analysis could be a useful tool even in the case where no apparent contamination source is found.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.203-208
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• 1985

Partial characterization of B. thuringiensis var. kurstaki 3ab temperature-sensitive mutants was carried out through biochemical analyses, utilization tests of carbohydrate sources, antobiotic resistant test, hemolytic reaction test, growth measurement of Fructus gardenia sxtrant medium and toxicity test against mice. Six ts mutants, ts-U154, ts-U601, ts-U602, ts-U603, tsU-604, and ts-U788 could not produce urease, ts-U603 lost its motility, ts-U154 could not use salicin and cellobiose and ts-U603 not ribose. All ts mutants except ts-U154 and wild type strain were resistant to cephalothin, ampicillin, and penicillin. but ts-U154 was sensitive to the three. Four mutants, ts-U21, ts-U74, ts0U131 and ts-U154 did not form pigment colonies on the F. gardenia medium. All the mutants and wild type strain showed hemolysis reaction on the blood agar. The B. thuringiensis and mutants were not toxic to mice.

• Journal of Sensor Science and Technology
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• v.13 no.3
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• pp.213-217
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• 2004

The general method to find a H. pylori in the stomach is the rapid urease test but it is only used to decide the infection with H. pylori. In this study, it is tried to develope fiber-optic pH sensor which can be used with gastroscop to quantify H. pylori. To measure the degree of infection with H. pylori, the color change of phenol red according to the degree of pH is measured by optical fibers with different light sources and the optimum distance from a sample to the end of sensor tip is decided by measuring the maximum reflectivity from a sample. Also the sensitivity study is carried out to decide the optimum light source which has sensitive change of reflectivity to the change of pH. It is expected that the fiber-optic pH sensor which measures the degree of infection with H. pylori exactly can be developed.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.26-32
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• 2013

Butanol-resistant bacteria were isolated from butanol solvent. The cell growth of isolated strains declined with increasing concentrations of butanol, and isolated strain BRS02 displayed more resistance to 12.5 g/L of butanol than other isolated strains. In addition, strain BRS251, which was resistant to even higher concentrations of butanol, was developed by the mutation of BRS02 using UV. BRS251 could grow in LB medium containing up to 17.5 g/L of butanol, 32.5 g/L of propanol, or 6 g/L of pentanol, whereas the control strain Escherichia coli was found to be tolerant to 7.5 g/L of butanol, 20 g/L of propanol, or 2 g/L of pentanol. The isolated BRS02, a Gram(+) bacterium seen to have a cocci form under the microscope, grew in 6.5% NaCl. According to biochemical tests, BRS02 can metabolize and produce acid with D-galactose, D-maltose, D-mannitol, D-mannose, methyl-${\beta}$-Dglucopyranoside, D-ribose, sucrose, or D-trehalose, as carbon sources. Also, this strain showed resistance to bacitracin, vibriostatic agent O/129, and optochin, alongside positive activities for arginine dihydrolase, ${\alpha}$-glucosidase, and urease. The BRS02 strain was identified as Staphylococcus sp. by analyses of the 16S rRNA gene, phylogenetic tree, and biochemical tests.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.67-75
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• 2012

This paper presents an environment-friendly sand cementation method by precipitating calcium carbonate using plant extracts. The plant extracts contain urease like $Sporosarcina$ $pasteurii$, which can decompose urea into carbonate ion and ammonium ion. It can cause cementation within sand particles where carbonate ions decomposed from urea combine with calcium ions dissolved from calcium chloride or calcium hydroxide to form calcium carbonate. Plant extracts, urea and calcium chloride or calcium hydroxide were blended and then mixed with Nakdong River sand. The mixed sand was compacted into a cylindrical specimen and cured for 3 days at room temperature ($18^{\circ}C$). Unconfined compression test, SEM and XRD analyses were carried out to evaluate three levels of urea concentration and two different calcium sources. As urea concentration increased, the unconfined compressive strength increased up to 10 times those without plant extracts because calcium carbonate precipitated more, regardless of calcium source. It was also found that the strength of specimen using calcium chloride was higher than that of specimen using calcium hydroxide.

• Applied Biological Chemistry
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• v.27
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• pp.56-67
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• 1984

As in many other country, the use of organic matter in Korea has long history. Farmers understand the value of organic matter as the source of plant nutrient and soil improving agent in general. Since 50 years ago, the sources of organic matter in paddy soils were compost, rice and barly straw, green manure, animal waste, fish and beancake, etc.. Application of green manures such as vetch and chinese milk vetch showed no significant effect on the yield of brown rice in paddy soil. On the other hand, the effects of compost and rice straw showed more significant on the yield of brown rice in paddy soil. Application of rice straw in rice cultivation is commonly made at different times between harvest, early spring and several weeks before transplanting. Considering the suitable paddy soil for application of rice straw under well to moderately well drained soil, the yield was pronounced more than poorly drained soil. Based on laboratory and field experimants, application of rice straw promoted the decrease of oxidation-reduction potential in well to moderately well drained soil. This results to be enhanced the release of some mineral nutrients,. such as potassium, calcium, silicon, and increase of availability of soil phosphorus. In the field experiments, results obtained from nitrogen fraction on the immobilization-mineralization of the tracer nitrogen applied in paddy soil,the amount and index of organic nitrogen incoporated in soil was more pronounced in rice straw application than control. Rice straw and its transformation products incoporated in the soil, provided the inflow of energy necessary to maintain heterotrophic microbes activities. Rice straw and its transformation products, especially soluble carbohydrate, enhanced the population of free-living heterotrophic $N_2$ - fixing microbes. Moreover, rice straw and its transformation products in paddy soil, enhanced the activities of soil enzymes such as dehydrogenase and urease.

• KSBB Journal
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• v.32 no.2
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• pp.124-132
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• 2017

A methane-oxidizing bacterium was isolated from rice paddy field soil around Jeollanam-do province, Korea, and characterized. The isolate was gram-negative, orange pigmented and short rod ($1.1-1.2{\times}1.6-1.9{\mu}m$). It was catalase and urease-negative but oxidase-positive. The strain utilized methane and methanol as sole carbon and energy sources. It had an ability to grow with an optimum pH 7.0 and an optimum growth temperature $30^{\circ}C$. The strain was resistant to antibiotic polymyxin B but sensitive to streptomycin, kanamycin, ampicillin, chloramphenicol and rifampicin. The isolate required copper for their growth with concentration range of $2-25{\mu}M$, with an optimum of $10{\mu}M$. Under optimal culture condition, specific cell growth rate and generation time were found to be $0.046hr^{-1}$ and 15.13 hr, respectively. Phylogenetic analysis based on 16S rDNA sequences indicated that the strain formed a tight phylogenetic lineage with Methylomonas koyamae with a value of 99.4% gene sequence homology. So, we named the isolate as Methylomonas sp. SM4. 8.6 mM methanol was accumulated in the reaction mixture containing 70 mM sodium formate and 40 mM $MgCl_2$ (MDH inhibitor) under atmosphere of methane:air (40:60) mixture for 24 hr at $30^{\circ}C$.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.386-393
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• 1999

Ethanol is considered as one of the most suitable substitutes for the petroleum, since it offers attractive functional features at an economical cost. Glucoamylase producing yeasts were isolated and characterized. Based on the morphological character, carbon fermentations, assimilation of carbon and nitrate, growth on vitamine-free medicine, and urease activity, five isolates of Saccharomyces diastaticus, two isolates of Saccharomycopsis fibuligera, and two of Schwanniomyces occidentalis, and each isolate of Ambrosiozyma monospora and Lipomyces kononenkoae were identified. Among 12 isolates, one of the S. diastaticus, E3 showed the highest activity of glucoamylase and identified as Saccharomyces diastaticus. The hydrolysis of starch by the E3 strain showed the release of considerable amount of reducing sugar, along with the reduction in iodine staining capacity. The product of action of glucoamylase, glucose was determined by thin-layer chromatography. The enzyme activity was found to be stable in broad pH range of $5.0{\sim}7.0$ with optimal activity at pH $5.0{\sim}6.0$. The enzyme showed optimal antivity at $50^{\circ}C{\sim}60^{\circ}C$. Soluble starch and glucose were better carbon sources for the enzyme production than xylose and glycerol. $Na^+\;and\;Mg^{2+}$ increased the glucoamylase activity, however $Hg^{2+}\;and\;Ag^{2+}$ inhibited the activity. Soluble starch was the best substrate for the enzyme activity.