• Food Science and Preservation
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• v.19 no.2
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• pp.308-314
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• 2012

Two hundred and twenty three yeast strains were randomly isolated from Korean traditional $nuruk$. Among them, six urease producing yeast strains (designated JJA, JJB, JJ22, SHA, SHC and SH10) were selected on the Christensen urea agar plates. They showed the same pattern in the PCR-RFLP analysis of the ITS I-5.8S-ITS II region digested with $Hae$III and $HinF$1 restriction endonucleases. Its DNA sequences showed 100% (strains SHA, SHC and SH10) and 99.8% (strains JJA, JJB and JJ22) identity with those of $Issatchenkia$ $orientalis$ type strain ATCC 24210. Phylogenetic analysis resulted in that all the strains were closely related to $I.$ $orientalis$. Two representative strains, JJ22 and SH10, showing the highest urease activities were selected for further characterization. Their morphological, physiological and biochemical characteristics were also the same as $I.$ $orientalis$. Therefore, both the two strains were identified as $I.$ $orientalis$. They could grow at a wide range of temperature between $20-40^{\circ}C$ as well as pH between 2.0 and 10.0. However, a higher level urease activity were obtained at acidic pH than that at alkalic pH. The maximal level of urease activity was obtained at $30^{\circ}C$ (strain SH10) or $35^{\circ}C$ (strain JJ22) and in a liquid medium adjusted to the initial pH 5.0.

• 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.

• KSBB Journal
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• v.29 no.5
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• pp.323-327
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• 2014

Microbially induced calcite precipitation is a naturally occurring biological process in which microbes produce calcite on the surface of the microorganisms by urease activity. In order to collect calcite forming bacteria (CFB) in Korea, we isolated 343 putative CFB strains from various environments over three year period (2011~2013) and selected 100 CFB strains. Average of calcite productivity was 10.56 mg/mL. And average of ammonium concentration by urease activity was $8.00{\mu}M$. Two useful CFB strains of the others were analyzed by 16S rRNA and identified as Sporosarcina sp. and Viridibacillus arenosi. The CFB strains presented in this study are indigenous microorganisms in Korea and they are expected to be applicable to a variety of environments in the country.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.281-288
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• 1999

Helicobacter species have been identified in or isolated from domestic carnivores, but their prevalence in different population of animals and their clinical significance are still unknown. This study was peformed to evaluate the prevalence of Helicobacter in clinically healthy dogs by urease test, culture, morphological examination and polymerase chain reaction (PCR) technique. Tissue samples from 70 dogs in Kangwon and Kyunggi areas from August 1998 to April, 1999, were examined. The detection rates of Helicobacter by urease activity of tissue-samples were 84.6%, 61.3% and 4.8 % in the fundus, the antrum and the duodenum, respectively. One strain of Helicobacter was isolated from the duodenum. It was identified as H canis by biochemical and morphorogical examination. The detection rates of Helicobacter by histological examination were 92.3%, 79.0% and 4.8% in the fundus, antrum and the duodenum, respectively. Helicobacter organisms were colonized more in the gastric pits than in the surface of epithelium, the gastric gland or the parietal cell. Although most of dogs were colonized with Helicobacter in tissue, gross lesions and specific histopathological lesions caused by Helicobacter in these tissues were not observed. The detection rate of Helicobacter by PCR was 78.6%. The histological examination was more sensitive than urease test, culture or PCR technique for the detection of Helicobacter.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.84-90
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• 2011

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt $V_{max}$ referring enzyme activity ($E_0$) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

• Journal of Microbiology
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• v.39 no.4
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• pp.279-285
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• 2001

Vibrio parahaemolyticus is a halophilic bacterium associated with seafood gastroenteritis. An unusual strain of Kanagawa-positive urease producing Vibrio parahaemolyticus O1:K1 was isolated from the environment and identified . A polymerase chain reaction assay revealed that this strain harbored both the tdh and the genes. The urease from this strain was studied. Maximum urease production was induced in LB medium containing 0.2% urea, 0.5% glucose, 2% NaCl and pH 5.5 with 6h of culti-vation at 37$\^{C}$ under aeration. Purification of urease was achieved by the process of whole cell lysate, 65% ammonium sulphate precipitation, DEAE-cellulose ion exchange column chromatography, Sepharose CL-6B gel filtration and oxirane activated Sepharose 6B-urea affinity chromatography with 203 fold purification and 2.2% yield. Analysis of the purified enzyme by SDS-PAGE demonstrated the presence of the subunits with a molecular weight of 85kDa, 59kDa, 41kDa and the molecular weight for the native enzyme by nondenaturing PAGE and gel filtration chromatography was 255kDa. The purified urease was stable at pH 7.5 and the opeimal pH in HEPES buffer was 8.0 The enzyme was stable at 60$\^{C}$ for 2 h with a residual activity of 32% . The addition of 10$\mu$M if NiCl$_2$maintained stability for 30 min. The Km value of the purified enzyme was 35.6 mM in urea substrate. The TD$\_$50/(median toxic dose) of the purified urease was 2.5$\mu\textrm{g}$/ml on human leukemia cells.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.519-526
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• 1992

The gene coding for urease of alkalophilic Bacillus pasteurii had been cloned in Escherichia coli previously. The urease protein was purified 63.1-fold by TEAE-cellulose, DEAE-Sephadex A-50, Sephadex G-150 and Sephadex G-200 chromatographies with a 7.3% yield from the sonicated fluid of the E. coli HB1Ol(pBUll) encoding B. pasteurii urease gene. The ureases of E. coli (pBUll) and B. pasteurii possessed as a $K_m$ for urea, 42.1 mM and 40.4 mM, respectively. They hydrolyzed urea with $V_{max}$ of 86.9$\mu$mol/min and 160$\mu$mol/min, respectively. Both ureases were composed with four subunits (Mrs 67,000) and a subunit (Mr 20,000). The molecular weight of both native enzymes was Mr 280,OOO$pm$10,000 determined by gel filtration chromatography and Coomassie blue staining of the subunits. The optimal reaction pH of both ureases were pH 7.5. The ureases were stabled in pH 5.5-10.5. The optimal reaction temperature of both ureases were $60^{\circ}C$, and the ureases were stable for an hour at $50^{\circ}C$, 40min at $60^{\circ}C$ and 10 min at $70^{\circ}C$ The activity of both enzymes were inhibited completely by $Ag^{2+}$, $Hg^{2+}$, $Zn^{2+}$, $Cu^{2+}$, and were inhibited 60% by CoH, 30% by $Fe^{2+}$ and 10% by $Pb^{2+}$. However it was increased by the addition of $Sn^{2+}$, $Mn^{2+}$, $Mg^{2+}$ at concentration of $1{\times}10^{-3}$M. Both ureases were inhibited completely by p-CMB and acetohydroxamic acid. The urease expressed in E. coli (pBU11) was inhibited 70% by SDS. The urease of B. pasteurii was inhibited 40% by hydroxyurea, whereas the recombinant urease of E. coli strain was inhibited 17%. Both enzymes were not inhibited by cyclohexanediaminetetraacetic acid (CDTA) and ethylendiaminetetraacetic acid (EDTA).

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.122-129
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• 1998

It were reported that antifungal mechanism of Enterobacter cloacae is a volatile ammonia that produced by the strain in soil, and the production of ammonia is related to the bacterial urease activity. A powerful bacterium SH14 against soil-borne pathogen Fusarium solani, which cause root rot of many important crops, was selected from a ginseng pathogen suppressive soil. The strain SH14 was identified as Bacillus subtilis by cultural, biochemical, morphological method, and $API^{circledR}$ test. From several in vitro tests, the antifungal substance that is produced from B. subtilis SH14 was revealed as heat-stable and low-molecular weight antibiotic substance. In order to construct the multifunctional biocontrol agent, the urease gene of Bacillus pasteurii which can produce pathogenes-suppressive ammonia transferred into antifungal bacterium. First, a partial BamH I digestion fragment of plasmid pBU11 containing the alkalophilic B. pasteurii l1859 urease gene was inserted into the BamH I site of pEB203 and expressed in Escherichia coli JM109. The recombinant plasmid was designated as pGU366. The plasmid pGU366 containing urease gene was introduced into the B. subtilis SH14 with PEG-induced protoplast transformation (PIP) method. The urease gene was very stably expressed in the transformant of B. subtilis SH14. Also, the optimal conditions for transformation were established and the highest transformation frequency was obtained by treatment of lysozyme for 90 min, and then addition of 1.5 ${mu}g$/ml DNA and 40% PEG4000. From the in vitro antifungal test against F. solani, antifungal activity of B. subtilis SH14(pGu366) containing urease gene was much higher than that of the host strain. Genetical development of B. subtilis SH14 by transfer of urease gene can be responsible for enhanced biocontrol efficacy with its antibiotic action.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.60-66
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• 2014

This study was carried out to investigate the characteristics of FOST (fermented omija sugar treatment extracts) using Lactobacillus brevis HLJ59. Antioxidant activities of FOST were evaluated through viable cell number of L. brevis HLJ59, DPPH radical scavenging activity, reducing power and SOD-like activity, compared to non-FOST(non-fermented omija sugar treatment extracts). Also it was to evaluate Angiotensin Converting Enzyme (ACE) and Urease inhibitory activity of FOST. The viable cell number of L. brevis was about $2.05{\pm}0.21{\times}10^8$, $6.31{\pm}0.56{\times}10^{11}$, and $8.14{\pm}0.14{\times}10^9$ at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. DPPH radical scavenging activity of FOST was about 60.3%, 71.8%, and 44.5% at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. The reducing power of FOST was about 0.92, 1.19, and 0.73 (OD at 700 nm) at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, and SOD-like activity of FOST was about 50.4%, 53.7%, and 33.4% at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. ACE and Urease inhibitory activity by FOST was about 47.4%, 78.2%, 56.4% and 58.1%, 83.4%, 63.2% at ${\times}2$, ${\times}5$, and ${\times}10$ dilution, respectively. The results indicated that the fermentation of omija sugar treatment extracts using Lactobacillus brevis HLJ59 increased the antioxidant activities campared to the non-fermented omija sugar treatment extracts.

• Microbiology and Biotechnology Letters
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• v.28 no.3
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• pp.161-166
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• 2000

Antifungal Activity and Identification of an Actinomycetes Strain Isolated from Mummified Peaches. Lirn, Tae Heon*, Jung Mok Lee, Tae Hyun Chang, and Byeongjin Chal. *Research Institute of Plant Nutrient, Oaeyu Co, Inc. Kyongsan 712-820, Korea, 1 Department of Agricultural Bi%g'f Chungbul< NatJ"onal Univershy, Cheongju 367-763, Korea - An actinomycetes strain which produced chitinase, urease, and antifungal substances to MoniliniaJhtcticola was isolated from peaches mununified by Moniliniafructicola. The strain TH-04 was identified as Streptomyces sp. based on cultural and lTIOIphological characteristics, cell wall diaminopimelic acid, and sugar patterns ofwhole~cell extracts. Streptomyces sp. TH~04 showed antifungal activity to several fungi including Moniliniafructicola, Colletotrichum gloeosporioides, Magnaponhe grisea, Rhizoctonia solani, Phytophthora capsici, Altemaria kikuchiana, Fusarium solani, and Fusarium O),ysporum. The optimum cultural conditions for the production of antifungal substances were $20^{\circ}C$pH 7, and 7 days.