• Korean journal of applied entomology
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• v.55 no.2
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• pp.177-188
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• 2016

The alpha-proteobacterium Wolbachia is one of the most important intracellular symbionts of arthropods. This Gram-negative bacterium is involved in many biological processes and is currently considered as a potential tool for biological control. Wolbachia is a cytoplasmic bacterium, maternally transferred through generations, and to facilitate its success, it has evolved several strategies that manipulate its host reproductive system to increase the number of infected individuals in the host population. The variety of Wolbachia was first recognized using genes wsp, 16S rRNA, ftsZ, gltA and groEL as molecular markers while strain genotypes of Wolbachia are determined of Multilocus sequence typing (MLST) and sequence of amino acid in region, hyper variable regions (HVRs) in protein WSP. Possible uses of the bacteria and their predominant phenotypes in control programs for agricultural pests and human disease vectors have been considered. Phenotypes are known to induce cytoplasmic incompatibility (CI), parthenogenesis induction (PI), feminization (F) and male killing (MK). Finally, applications of the bacterium in control programs of agricultural and medical insect pests have been discussed.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.243-248
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• 2016

RNase E (Rne) is an essential enzyme involved in the processing and degradation of a large portion of RNAs in Escherichia coli. The enzymatic activity of RNase E is controlled by regulators of ribonuclease activity, namely, RraA and RraB. Gram-positive bacterium Streptomyces coelicolor also contains homologs of Rne and RraA, designated as RNase ES (Rns), RraAS1, and RraAS2. In the present study, we investigated the effect of S. coelicolor RraAS1 on the ribonucleolytic activity of RNase E in E. coli. Coexpression of RraAS1 with Rne resulted in the decreased levels of rpsO, ftsZ, and rnhB mRNAs, which are RNase E substrates, and augmented the toxic effect of Rne overexpression on cell growth. These in vivo effects appeared to be induced by the binding of RraAS1 to Rne, as indicated by the results of co-immunoprecipitation analysis. These results suggested that RraAS1 induces ribonucleolytic activity of RNase E in E. coli.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.614-620
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• 1994

The effects of growth temperature and nutritional components on the synthesis of poly-3-hydroxybutyric acid, PHB, by filamentation-suppressed recombinant Escherichia coli XL1-Blue (pSYL107) were studied. After culturing XL1-Blue(pSYL107) for 48 hours in complex medium at 30$\circ$C, 7Al g/l of PHB could be obtained with the PHB content and PHB yield of 82% and 0.371 g PHB/g glucose, respectively. Lower concentration of PHB(3.2 g/l) was obtained when cultu- red at 37$\circ$C, which seemed to be due to the instability of this strain having amplified FtsZ activity. The PHB concentration of 3.75 g/l was obtained after culturing 60 hours in R medium supplemen- ted with 20 g/l glucose at 30$\circ$C, which was more than twice higher than that obtained with XL1-Blue(pSYL105). This suggested that the enhancement of PHB synthesis by suppressing filamenta- tion was more significant in a defined medium than complex medium. PHB synthesis could be further enhanced by supplementing a small amount of various complex nitrogen sources. When 5 g/l of beef extract was added to a defined medium, PHB concentration, PHB content, and PHB yield obtained after 60 hours of cultivation at 30$\circ$C were 7.46 g/l, 86%, and 0.375 g PHB/g glucose,respectively.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.796-808
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• 2018

The intracellular bacterium Wolbachia pipientis is widespread in arthropods. Recently, possibilities of novel Wolbachia-mediated hosts, their distribution, and natural rate have been anticipated, and the coconut leaf beetle Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), which has garnered attention as a serious pest of palms, was subjected to this interrogation. By adopting Wolbachia surface protein (wsp) and multilocus sequence type (MLST) genotypic systems, we determined the Wolbachia infection density within host developmental stages, body parts, and tissues, and the results revealed that all the tested samples of B. longissima were infected with the same Wolbachia strain (wLog), suggesting complete vertical transmission. The MLST profile elucidated two new alleles (ftsZ-234 and coxA-266) that define a new sequence type (ST-483), which indicates the particular genotypic association of B. longissima and Wolbachia. The quantitative real-time PCR analysis revealed a higher infection density in the eggs and adult stage, followed by the abdomen and reproductive tissues, respectively. However, no significant differences were observed in the infection density between sexes. Moreover, the wsp and concatenated MLST alignment analysis of this study with other known Wolbachia-mediated arthropods revealed similar clustering with distinct monophyletic supergroup B. This is the first comprehensive report on the prevalence, infection dynamics, and phylogeny of the Wolbachia endosymbiont in B. longissima, which demonstrated that Wolbachia is ubiquitous across all developmental stages and distributed in the entire body of B. longissima. Understanding the Wolbachia infection dynamics would provide useful insight to build a framework for future investigations, understand its impacts on host physiology, and exploit it as a potential biocontrol agent.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.825-830
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• 2001

Escherichia coli, which harbored the ars operon from a plasmid pMH12 of Klebsiella oxytoca D12, showed filamentation due to the expression of ars genes in the presence of arsenite. The continued DNA replication in the absence of cell division was revealed, since nucleoids abound with DAPI appeared to be arranged in chains. In contrast to overexpression of arsA, its frame-shift mutant and knock-out mutant lost filamentation in the presence of arsenite, which suggested that ars-induced division block was dependent on expression of arsA. ArsA-induced division inhibition was not a consequence of an inhibition of DNA replication, and the inability of arsenite to induce an SOS response indicated that arsA-mediated division inhibition was dependent on the expression of the gene product encoded by the minB operon. ArsA is a peripheral membrane protein with an ATP-binding domain, which is homologous to MinD that requires ATP-dependent efflux. These results suggested that ArsA could possibly recruit MinC to the membrane and modulate cytoplasmic FtsZ to block assembly at the middle of the cell.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.257-262
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• 2018

Avian pathogenic E. coli (APEC) causes severe economic losses in the poultry farms, due to systemic infections leading to lethal colisepticemia. It causes a variety of diseases from air sac infection to systemic spread leading to septicemia. Secondary infection contains opportunistic infections due to immunosuppression disease. Collibacillosis causes the great problems in the poultry industry in Korea. Thus, it is necessary to identify and classify the characteristics of E. coli isolate of chicken origin to confirm the diversity of symptoms and whether they are transmitted among the farms. Fragment analysis is identify the difference in the number of Variable-Number Tandem-Repeats (VNTRs) for genotyping. VNTRs have repeating structure (Microsatellite, Short tandem repeats; STR, Simple sequence repeats; SSR) in the chromosome. This region can be used as a genetic marker because of its high mutation rate. And various lengths of the amplified DNA fragment cause the difference in the number of repetition of the DNA specific site. The number of repetition sequences indicates the separated size of fragments, so the each fragments can be distinguished by specific samples. The results of the sample show that there is no difference in six microsatellite loci (yjiD, aidB, molR_1, ftsZ, b1668, yibA). There are differences among the farms in relation of the number of repetitions of other six microsatellite loci (ycgW, yaiN, yiaB, mhpR, b0829, caiF). Four (ycgW, yiaB, b0829, caiF) of these six microsatellite loci show statistically significant differences (P<0.05). It means that the analysis using four microsatellite loci including ycgW, yiaB, b0829, and caiF can confirm among the farms. Five E. coli samples in one farm have same SSR repetition at all markers. But, there are significant differences from other farms at Four (ycgW, yiaB, b0829, caiF) microsatellite loci. These results emphasize again that the four microsatellite loci makes a difference in the amplified DNA fragments, enabling it to be used for E. coli genotyping.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.9-19
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• 2011

The Bacillus subtilis pyrimidine biosynthetic (pyr) operon encodes all of the enzymes for the de novo biosynthesis of Uridine monophosphate (UMP) and additional cistrones encoding a uracil permease and the regulatory protein PyrR. The PyrR is a bifunctional protein with pyr mRNA-binding regulatory funtion and uracil phosphoribosyltransferase activity. To study the global regulation by the pyrR deletion, the proteome comparison between Bacillus subtilis DB104 and Bacillus subtilis DB104 ${\Delta}$pyrR in the minimal medium without pyrimidines was employed. Proteome analysis of the cytosolic proteins from both strains by 2D-gel electrophoresis showed the variations in levels of protein expression. On the silver stained 2D-gel with an isoelectric point (pI) between 4 and 10, about 1,300 spots were detected and 172 spots showed quantitative variations in which 42 high quantitatively variant proteins were identified. The results showed that production of the pyrimidine biosynthetic enzymes (PyrAA, PyrAB, PyrB, PyrC, PyrD, and PyrF) were significantly increased in B. subtilis DB104 ${\Delta}$pyrR. Besides, proteins associated carbohydrate metabolism, elongation protein synthesis, metabolism of cofactors and vitamins, motility, tRNA synthetase, catalase, ATP-binding protein, and cell division protein FtsZ were overproduced in the PyrR-deficient mutant. Based on analytic results, the PyrR might be involved a number of other metabolisms or various phenomena in the bacterial cell besides the pyrimidine biosynthesis.