• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.357-366
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• 2019

We first confirmed the involvement of MalQ (4-${\alpha}$-glucanotransferase) in Escherichia coli glycogen breakdown by both in vitro and in vivo assays. In vivo tests of the knock-out mutant, ${\Delta}malQ$, showed that glycogen slowly decreased after the stationary phase compared to the wild-type strain, indicating the involvement of MalQ in glycogen degradation. In vitro assays incubated glycogen-mimic substrate, branched cyclodextrin (maltotetraosyl-${\beta}$-CD: G4-${\beta}$-CD) and glycogen phosphorylase (GlgP)-limit dextrin with a set of variable combinations of E. coli enzymes, including GlgX (debranching enzyme), MalP (maltodextrin phosphorylase), GlgP and MalQ. In the absence of GlgP, the reaction of MalP, GlgX and MalQ on substrates produced glucose-1-P (glc-1-P) 3-fold faster than without MalQ. The results revealed that MalQ led to disproportionate G4 released from GlgP-limit dextrin to another acceptor, G4, which is phosphorylated by MalP. In contrast, in the absence of MalP, the reaction of GlgX, GlgP and MalQ resulted in a 1.6-fold increased production of glc-1-P than without MalQ. The result indicated that the G4-branch chains of GlgP-limit dextrin are released by GlgX hydrolysis, and then MalQ transfers the resultant G4 either to another branch chain or another G4 that can immediately be phosphorylated into glc-1-P by GlgP. Thus, we propose a model of two possible MalQ-involved pathways in glycogen degradation. The operon structure of MalP-defecting enterobacteria strongly supports the involvement of MalQ and GlgP as alternative pathways in glycogen degradation.

• Journal of Microbiology
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• v.34 no.4
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• pp.320-326
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• 1996

To analyze the effects of host versus plasmid on survival of 2, 4-degrading bacteria in environmental samples, strains Pseudomonas cepacia/pJP4, Alcaligenes JMP228/pJP4, P. cepacia/p712, and Alcaligenes JMP228/p712 were separately inoculated into samples of field soil, paddy soil, lake water, and river water, and then the changes of their populations were measured. The strains used contained a 2, 4-D degradative plasmid, either pJP4 conferring fast-growing property to the host or p712 conferring slow-growing property, and were resistant to antibiotics such that the inoculated strains could be enumerated against the indigenous microbial populations. In sterile environmental samples, these strains were stably maintained at the levels used for inoculation, except in sterile paddy soil where Alcaligenes JMP228 strains died drapidly. In natural soil samples for four strains declined steadily with time, but in naturla water samples their polulations fell rapidly at the early phase and then remained almost constant. When the environmentla samples were treated with 2, 4-D, P. cepacia/pJP4 and P. cepacia/p712 maintained significant numbers, while Alcaligenes JMP228/pJP4 and Alcaligenes JMP228/p712 declined significantly in most of the samples. The results indicated that the survivability of genetically modified microorganisms could vary depending on the environments and that their abundance in the environments under s2, 4-D selection was markedly influenced by the nature of the 2, 4-D degradative plasmid as well as type of the host strain.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.3
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• pp.73-78
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• 2011

The pH is one of the most important factors affecting metabolism pathway and activity of hydrogen producing bacteria. The effect of operational pH on anaerobic hydrogen fermentation of food waste was evaluated at mesophilic condition. In this batch experiment, the initial pH was 8.0 and the operational pH was controlled at 4.7~7.0 by the addition of 5N KOH solutions. At the operational pH of 4.7, the lag phase and the maximum hydrogen production were 47.9h and 534.4 mL, respectively. The lag phase and the maximum hydrogen production were decreased as the operational pH increased. At the operational pH of 7.0, the lag phase and the maximum hydrogen production were 4.2 h and 213.8 mL, respectively.

• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.277-284
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• 1998

Dendritic macromolecules of the first to fourth generation were synthesized, using alkenylation and hydrosilation cycles with allylmagnesium bromide and dichloromethylsilane as building blocks and siloxane tetramer $(Me(CH_2=CH)SiO)_4$, as core molecule. By the reaction of the dichloromethylsilyl-capped generation (G4P) with p-bromophenol, p-phenylphenol and lithium phenyethynylide, dendrimers with specific functions (G4P-BP (Mw: 16,300), G4P-PP (16,121), and CAP-PA (11,764)) have been produced. Analysis of new dendrimers by NMR, UV and MALD1 mass spectrometry suggests that they are pure and unified.

• Journal of Environmental Science International
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• v.8 no.2
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• pp.227-231
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• 1999

This study was conducted to investigate the removal characteristics of $PO_4^{3-}-P$ contained in livestock wastewater using waste concrete. With small particle size, increased dosage and temperature of water, $PO_4^{3-}-P$ was well removed by waste concrete.$PO_4^{3-}-P$ was removed by adsorption reaction in low pH of the primary phase, but the crystallization reaction predominated for increasing pH with passed time. As a result of adapting the adsorption isotherm equation, $PO_4^{3-}-P$ removal was more affected by the crystallization reaction than the adsorption reaction. In the SEM micrograph, there was no evident change on the waste concreter surface. Particle size was plate-phase before reaction but appeared a dense form to progress in the crystallization reaction.

• Journal of Microbiology
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• v.45 no.6
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• pp.534-540
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• 2007

The Streptomyces coelicolor A3(2) genome contains six operons (rrnA to F) for ribosomal RNA synthesis. Transcription from rrnD occurs from four promoters (p1 to p4). We found that transcripts from the p1 and p3 promoters were most abundant in vivo in the early exponential phase. However, at later phases of exponential and stationary growth, transcripts from the p1 promoter decreased drastically, with the p3 and p4 transcripts constituting the major forms. Partially purified RNA polymerase supported transcription from the p3 and p4 promoters, whereas pure reconstituted RNA polymerase with core enzyme (E) and the major vegetative sigma factor ${\sigma}^{HrdB}$ ($E{\cdot}{\sigma}^{HrdB}$) did not. In order to assess any potential requirement for additional factor(s) that allow transcription from the p3 and p4 promoters, we fractionated a partially purified RNA polymerase preparation by denaturing gel filtration chromatography. We found that transcription from the p3 and p4 promoters required factor(s) of about 30-35 kDa in addition to RNAP holoenzyme ($E{\cdot}{\sigma}^{HrdB}$). Therefore, transcription from the p3 and p4 promoters, which contain a consensus -10 region but no -35 for ${\sigma}^{HrdB}$ recognition, are likely to be regulated by transcription factor(s) that modulate RNA polymerase holoenzyme activity in S. coelicolor.

• Journal of environmental and Sanitary engineering
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• v.9 no.2
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• pp.1-7
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• 1994

Rainwater was collected in Seoul area from January 1991 to December 1993 (over 3years) and by the analysis of the chemical components contained in rainwater, investigated the components that effect on rainwater pH Through the above studies the following conclusions were obtained. 1) Method for Averaging pH Volume weighted method is considered to be acceptable providing that precipitation is measured at the same time when the samples are taken, without precipitation data a simple averaging method should be the next choice. 2) Annual average rainwater pH was 4.98 in 1991, 4.80 in 1992, 4.67 in 1993, measurement range was 3.6-8.1. 3) In the relationship between rainwater pH and rainfall amounts rainwater pH for light rain(<15mm rainfall) was existent in the wide range(pH 4-7), but for heavy rain was corresponded to the annual average values. 4) Annual frequency of pH was Birrndat the frequency($\gamma $) between the density of the [$H^{+}$] and pH in the rainwater(over 3years ), $NO_{3}^{-}$ was excellent and the obtained results was 0.62 in 1992. Also In the correlation coefficient($\gamma $) according to the pH range $SO_{4}^{2-}, NO_{3}^{-}$, were 0.85 ,0.68 at 3.6 $Cl^-$ was 0.99(1993). At 4.1$NO_{3}^{-}(\gamma=0.48)$ in 1992, SO_4^{2-}($\gamma$=0.54), $NO_{3}^{-}(\gamma$=0.72), $Cl^- (\gamma$=0.49) in 1993. 6) pH values gradually increased with increase in $Ca^{2+}/SO_{4}^{2-}$.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.46-49
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• 2005

Curdlan, a natural $\beta-1,3-glucan,$ has been studied as drug carrier due to its unique properties including its thermal gelling characters. In this study, curdlan was chemically acetylated for pH-sensitive drug delivery. Curdlan acetate microspheres(CAMs) were prepared by the solvent evaporation method. The size of the CAMs was below $200{\mu}m.$ The drug loading efficiency of microspheres was approximately $58.44\%$. In the swelling test, the CAMs showed pH-sensitive behavior. The swelling capacity of microspheres at pH 7.4 was much greater than at pH 1.4. Also, release rate of indomethacin(IND) at pH 7.4 from the CAMs was faster than that at pH 1.4. Therefore the CAMs have potential for the controlled release of IND over an extended period of time.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.221-228
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• 1976

The kinetics of hydrolysis of hydrazonyl bromides $(p-H,\;p-CH_3,\;p-OCH_3,\;p-Br,\;p-Cl\;&\;p-NO_2)$ have been investigated by UV spectrometry in $60{\%}$ dioxane-water at $25^{\circ}C$ and a rate equation which can be applied over wide pH range was obtained. Below pH2, the rate of hydrolysis of a series of hydrazonyl bromide is accelerated by electrondonating group (${\rho}$ = -0. 94) whereas at the pH values greater than 4, the ${\rho}$-value is 0.54. The rate equation, solvent-, substituent-and bromide ion-effect on the rate of hydrolysis are rationalized in terms of $S_N1$ and $S_N2$ mechanism: below pH 2, the hydrolysis proceed through $S_N2$, however, above pH 4, the hydrolysis is started by the attack of hydroxide ion and in the range pH 2{\sim}$4, these two reactions occur competitively.

• YAKHAK HOEJI
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• v.43 no.6
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• pp.789-792
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• 1999

The complete nucleotide sequence of pKH4, a small multidrug resistance (smr) plasmid isolated from multidrug resistant Staphylococcus aureus SA5, was determined. Sequence analysis has revealed that pKH4 has two open reading frames for Rep and Smr proteins. The comparison of the amino acid sequence of Smr protein of pKH4 with those of other Smr proteins of various Staphylococcus showed that Smr protein of pKH4 is a new member of the SMR family.