• Parasites, Hosts and Diseases
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• v.29 no.2
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• pp.181-188
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• 1991

Epidemiological studies on host rodents of tsutsugamushi disease were carried out during the period of July∼September 1990 at nine localities of central Korea. Among total 111 wild rodents trapped by the modified Sherman live traps, 103 were Apodemus agrarius (92.8%), seven were Crocidura lasiura (6.3%) and one was Microtus fortis (0.9%) , showing 24.0% of trapping rate in winter, 11.7% in spring, 11,2% in summer and 12.0% in autumn. Out of 103 A. agrarius 84 were parasitized by chiggers, showing 81.6% of the infestation rate and 43.0 of the chigger index. The antibody positive rate of A. agrarius sera to Rickettsia tsutsugamushi was significantly variable by locality, being in the range of 0∼78.6%. The seasonal change of the antibody positive rate at Dorai 5-ri, Goyang-gun was 75.8% in average during November∼March, decreased to 30.3% in April and further decreased to 13.3% in average during May∼August. Among 33 antibody positives, 31 were Karp strain and two were Gilliam. Seven Crocidura lasiura sera showed all negative. R. tsutsugamushi organisms were isolated from three A. ngrarius out of 94 mice tested, showing 3.2% of the infection rate.

• Korean Journal of Microbiology
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• v.48 no.1
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• pp.1-7
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• 2012

This study explores the interaction between the production of indole-3-acetic acid (IAA), a typical phytohormone auxin and the role of IAA biosynthetic pathways in each IAA producing rhizobacterial strain. The bacterial strains were isolated from rhizosphere of wild plants and identified as Acinetobacter guillouiae SW5, Bacillus thuringiensis SW17, Rhodococcus equi SW9, and Lysinibacillus fusiformis SW13. A. guillouiae SW5 exhibited the highest production of IAA using tryptophan-dependent pathways among the 4 strains. When indole-3-acetamide (IAM) was added, Rhodococcus equi SW9 showed the highest IAA production of $3824{\mu}g/mg$ protein using amidase activity. A. guillouiae SW5 also showed the highest production of IAA using two pathways with indole-3-acetonitrile (IAN), and its nitrile hydratase activity might be higher than nitrilase. B. thuringiensis SW17 showed the lowest IAA production, and most of IAA might be produced by the amidase activity, although the nitrilase activity was the highest among 4 strains. The roles of nitrile converting enzymes were relatively similar in IAA synthesis by Lysinibacillus fusiformis SW13. Tryptophan-independent pathway of IAA production was utilized by only A. guillouiae SW5.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.101-104
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• 2011

Cellobiose dehydrogenase(CDH) as a hemoflavoenzyme is secreted out of cell in the cellulose degradation. As CDH strongly bound to amorphous cellulose, it helps cellulose hydrolysis by cellulase. CDH may have an important role of saccharification process for bioethanol production. In this study, Phanerochaete chrysosporium ATCC 32629 was selected for the production of CDH among other strains tested. The optimal temperature and pH of CDH produced by P. chrysosporium ATCC 32629 were ${55^{\circ}C}$ and 4, respectively. To improve the activity of CDH, the mutation of P. chrysosporium was performed using proton beam that has high energy level partially. As a result, P. chrysosporium mutant with the high activity was selected at 1.2 kGy in a range of 99.9% lethal rate. The CDH and $\beta$-glucosidase activities of mutant were 1.4 fold and 20 fold higher than those of wild strain. Therefore, P. chrysosporium mutant with the high activities of CDH and $\beta$-glucosidase was obtained from mutation by proton beam irradiation.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.56-64
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• 2015

It has been known for some time to the wine industry that non-Saccharomyces yeasts play an important role in increasing volatile components through the secretion of extracellular enzymes. The objective of this study was to investigate what types of enzymes are produced by 1,007 non-Saccharomyces yeast strains isolated from Korean fermented foods. Among 1,007 yeast strains, the 566, 45 and 401 strains displayed β-glucosidase, glucanase and protease activity, respectively. In addition, the 563 and 610 strains possessed tolerances against cerulenin and TFL, and the 307 strain was tolerant to 15% ethanol. Yeasts producing harmful biogenic amines and hydrogen sulfide were excluded from further study, and eventually 12 yeast strains belonging to the genera Wickerhamomyces, Hanseniaspora, Pichia, Saccharomyces were identified, based on the 26S rRNA gene sequences. Among the 12 strains, the 9 and 5 strains possessed glucose and ethanol tolerance, respectively. Yeasts belonging to the genus Saccharomyces produced more than 8% alcohol, but non-Saccharomyces yeasts produced only 3% alcohol.

• Journal of Microbiology and Biotechnology
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• v.22 no.4
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• pp.555-562
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• 2012

PCR was performed to analyze the ${\beta}$-lactamase genes carried by ampicillin-resistant Vibrio spp. strains isolated from marine environments in Korea between 2006 and 2009. All 36 strains tested showed negative results in PCR with the primers designed from the nucleotide sequences of various known ${\beta}$-lactamase genes. This prompted us to screen new ${\beta}$-lactamase genes. A novel ${\beta}$-lactamase gene was cloned from Vibrio alginolyticus KV3 isolated from the aquaculture water of Geoje Island of Korea. The determined nucleotide sequence (VAK-3 ${\beta}$-lactamase) revealed an open reading frame (ORF) of 852 bp, encoding a protein of 283 amino acids (aa), which displayed low homology to any other ${\beta}$-lactamase genes reported in public databases. The deduced 283 aa sequence of VAK-3, consisting of a 19 aa signal peptide and a 264 aa mature protein, contained highly conserved peptide segments specific to class A ${\beta}$-lactamases including the specific amino acid residues STFK (62-65), SDN (122-124), E (158), and RTG (226-228). Results from PCR performed with primers specific to the VAK-3 ${\beta}$-lactamase gene identified 3 of the 36 isolated strains as V. alginolyticus, Vibrio cholerae, and Photobacterium damselae subsp. damselae, indicating the utilization of various ${\beta}$-lactamase genes including unidentified ones in ampicillin-resistant Vibrio spp. strains from the marine environment. In a mating experiment, none of the isolates transfered the VAK-3 ${\beta}$-lactamase gene to the Escherichia coli recipient. This lack of mobility, and the presence of a chromosomal acyl-CoA flanking sequence upstream of the VAK-3 ${\beta}$-lactamase gene, led to the assumption that the location of this new ${\beta}$-lactamase gene was in the chromosome, rather than the mobile plasmid. Antibiotic susceptibility of VAK-3 ${\beta}$-lactamase was indicated by elevated levels of resistance to penicillins, but not to cephalosporins in the wild type and E. coli harboring recombinant plasmid pKV-3, compared with those of the host strain alone. Phylogenetic analysis showed that VAK-3 ${\beta}$-lactamase is a new and separate member of class A ${\beta}$-lactamases.

• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.216-222
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• 2002

In order to evaluate the antifungal activity of bacteria against plant pathogenic fungi, 8 bacteria were isolated from mushroom compost hot spring, seaweed, and forest soil and mutants from them were induced by $LD_{95}$ gamma radiation($^{60}Co$). Bacillus circulans K1, Burkholderia gladioli K4 and Bacillus subtilis YS1 showed wide antifungal spectrum against 12 kinds of plant pathogenic fungi. From the radiation sensitivity test, B. gladioli K4 was very sensitive to gamma radiation and its $D_{10}$ value was 0.11 kGy. Antifungal activities of B. circulans Kl-1004 and B. subtilis YS1-1009, which were induced by the radiation of $^{60}Co$ increased against Botryosphaeria dothidea. The mutant strains, B. subtilis YS1-1006 and B. subtilis YS1-1009 were resistant to tebuconazole and copper hydroxide. SAR535, SAR5108, and SAR5118 mutated from Streptomyces sp. SAR01 were antifungal activity deficient mutants against 5 kinds of plant pathogenic fungi compared to wild strain, so that they could be supposed to be model strains far studying antifungal mechanism. It is suggested that various functional types of mutants could be induced by gamma radiation and applied usefully.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.83-88
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• 1998

Heavy metal removal by Z. ramigera 115 and soluble slime polymer producing mutant Z. ramigera 115SLR was investigated. Both strains showed similar tolerance against $Cd^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Ni^{2+}$ and $Fe^{2+}$. When cells were cultivated in the presence of 500 ppm $Cd^{2+}$, the mutant strain removed 1.5 fold more metal than the wild type did at same biomass. Metal adsorption capacities were in the order of Z. ramigera l15SLR polymer > Z. ramigera 115 polymer > Z. ramigera 115 cell >Z. ramigera l15SLR cell. The optimum pH for metal adsorption was 7.5. Langmuir and Freundlich isotherms indicated that Qmax and 1/n of Z. ramigera l15SLR polymer were 164.2 mg $Cd^{2+}$/g dw and 0.496, respectively. These results showed that the polymer of Z. ramigera l15SLR could be used as an effective metal adsorbate.

• The Journal of Korean Society of Virology
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• v.29 no.2
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• pp.129-136
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• 1999

Transient transfection assay has been done to evaluate whether the c-jun activation would be prerequisite to the induction of permissiveness against human cytomegalovirus using in vitro cell model in which U937 has been induced to express CD11b and CD14 to become potential monocyte/macrophage cells by TPA treatment. U937 cells were treated with $10\;{\mu}M$, $50\;{\mu}M$ or $100\;{\mu}M$ of TPA. The cell morphology change was observed and the expression of the CD11b and CD14 was confirmed by FACS. Differentiated cells were transfected with pJLuc reporter vector which contained the wild type murine c-jun promoter spanning the SP1, CTF, ATF/CREB and MEF-2 binding sites upstream of the firefly luciferase gene. After 48 hrs of transfection, the cells were infected with HCMV Towne strain and the luciferase activity was assessed at 1 hand 4 h pi. The transfection assay showed no activation of the c-jun promoter at 1 h pi, instead, it showed 2 times increase of the its activity at 4 h pi. There was no difference of the c-jun promoter activation between TPA treated and untreated U937 cells, implying that c-jun activation might not be prerequisite for allowing cells to be premissive to HCMV, although HCMV infection itself could activate c-jun promoter.

• Korean Journal of Microbiology
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• v.37 no.1
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• pp.28-36
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• 2001

These studies were carried out to understand the mechanisms of genes which are related in cell cycle progression at G1/S phase. Mutants involved in cell cycle progression and regulation in Saccharomyces cerevisiae were isolated and characterized. To isolate new mutants, we screened the sensitivity to ciclopirox olamine (CPO) which inhibits the cell cycle traverse at or very near the G1/S phase boundary in HeLa cell and budding yeast. As results, we isolated 30 mutants and named cos(ciclopirox olamine sensitivity: cos27∼cos57) mutants. To determine the phenotype of mutants, we examined the sensitivity to methyl-methane sulfonate (MMS) and hydroxyurea (HU). Several mutants were sensitive to MMS and HU. According to these Phenotypes, cos mutants were grouped into four. Group I mutants are cos27, cos28, cos32, cos33, cos36, cos37, cos40, cos42, cos46, cos50, cos52 and cos53 which show MMS, HU sensitivities and might act at a checkpoint pathway during S phase. Group II mutants are cos43 and cos48 which show MMS sensitivities and might act at a checkpoint pathway during Gl or G2 phase. Group III mutants are cos35, cos47, cos54, cos55 and cos56 which show HU sensitivities and might act at a progress pathway during S phase. Finally, Group IV mutants are cos29, cos30, cos31, cos34, cos38, cos39, cos41, cos44, cos45, cos49, cos51 and cos57 which show only CPO sensitivities. Moreover, we examined the terminal phenotype of mutants under fluorescent microscope and then found one of S phase checkpoint related mutant(cos37). Furthermore, we constructed the heterozygote strain between mutant and wild type haploid strains to study their genetic analysis of cos mutants.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.118-122
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• 1995

Escherichia Coli ornithine transcarbamylase is the enzyme which catalyzes the L-citrulline biosynthesis from L-ornithine and carbamyl phosphate. To facilitate the purification of enzyme which will be used for many biochemical studies such as structure and function relationships and catalytic mechanisms, the cloning and expression of E. coli argI gene for ornithine transcarbamylase was conducted. argI was amplified from genomic DNA of E. coli strain of $DH5{\alpha}$, by polymerization chain reaction (PCR) method. The amplified argI gene was ligated to the prokaryotic expression vector pKK223-3 and used for transformation of E. coli TB2 which was deficient of ornithine transcarbamylase. The over-produced enzyme by the tnansformant was purified by ammonium sulfate fractionation, heat denaturation and affinity chromatography. The result of SDS denaturation gel electrophoresis for the purified enzyme showed a single band of about 38 kDa of ornithine transcarbamylase. Kinetic data for the expressed enzyme gave almost the s?????? values as those of the wild type enzyme. The $k_{cat}$, of the enzyme was $1.0{\times}10^5min^{-1}$, and $K_ms$ for ornithine and carbamyl phosphate were 0.35 mM and 0.06 mM, respectively.