• Journal of Korean Society of Forest Science
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• v.76 no.1
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• pp.33-40
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• 1987

Simulated acid rain (pH 4.0, pH 2.0) containing sulfuric and nitric acid in the ratio of 60:40 (chemical equivalent basis) diluted with underground water, and underground water (pH 6.5) as control were treated on potted Pines koraiensis seeds during the growing season (May 1 to August 31) in 1985. The regime of artificial acid rain, in terms of spray frequency and amount per plot, was simulated on the basis of climatological data averaged for 30 years of records. The seedling growth, contents of chemical substances in needles and chemical properties of the tested soil were compared among the various pH levels of acid rain on October 31, 1985. Following results were obtained. 1. With decreasing pH levels of acid rain, S and $K_2O$ contents in leaf tissue were increased, but MgO and $P_2O_5$ contents were decreased. 2. Soil pH was dropped, and exchangeable aluminum content in the tested soil was dramatically increased as the pH levels of acid rain decreased. 3. Exchangeable calcium, magnesium, potassium contents, and base saturation degree of the soil were significantly decreased with decreasing pH levels of acid rain. 4. Sulfate concentrations in the soil were significantly increased as rain pH decreased, but total nitrogen and available phosphate contents were not influenced by acid rain.

• Journal of Life Science
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• v.8 no.4
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• pp.387-394
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• 1998

A thermophilic bacterium (strain DG0303) producing a thermostable $\alpha$-glucosidase was isolated from manure and identified as Bacillus sp. Strain DG0303 produced high level of $\alpha$-glucosidase compared with other thermophilic Bacillus strains. The cellular protein patterns were also compared with other Bacillus strains by sodium dodecyl sulfatepolyacrylamide gel electrophoresis(SDS-PAGE). On the basis of 16S rDNA analysis the Bacillus sp. DG0303 was found to be a member of Bacillus rDNA group 5. The optimum temperature for growth was 65$\circ$C and no growth was obtained at 40$\circ$C or 75$\circ$C. The optimum pH for growth was 5.5 to 8.5. $\alpha$-glucosidase activity was produced during growth and most activity was detected in the culture supernatant. The $\alpha$-glucosidase production was constitutive in the absence of carbohydrates. High level of enzyme activity was detected when the culture was grown on medium containing starch. Addition of glucose resulted in the repression of the $\alpha$-glucosidase production. The optimum pH and tempoerature for enzyme activity were pH 5.0 and 65$\circ$C, respectively. When analyzed by zymogram, the culture supernatant showed a single $\alpha$-glucosidase band with a molecular weight of approximately 60,000.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.285-290
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• 1989

The biololgical effect of the preemergence rice field herbicide, butachlor(commercial name, Machete) on purple nonsulfur photosynthetic bacterium Rhodospirillum rubrum KS-301 has been studied under cultural conditions. Bacterial growth showed a tendency to decline according to the degree of the concentration of butachlor until $10^{-3}$ M and slmost stopped at $10^{-2}$M. The growth inhibitory action at $10^{-3}$M of butachlor was evident (4.2-18.7% inhibition of growth rate) but had little effect in nitrogen fixation. Conversely, there was a little enhancement effect(1%) in pyruvate, dinitrogen gas growing cultures. At concentration of $10^{-3}$ M, instead of spiral form, rod shapes were observed through phase contrast microscope and instead of vesicular intracytoplasmic membrane, irregular tubular forms were observed through electron microscope. Alkaline pH value slightly reversed tha inhibitory action of butachlor.

• Journal of Dairy Science and Biotechnology
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• v.41 no.3
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• pp.138-148
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• 2023

In this study, Lactococcus lactis subsp. hordniae JNU533 (JNU533) was isolated from Swiss-type cheese, and the bacteriocin produced by this strain was characterized. The spot-on-lawn assay was used to determine the antimicrobial spectrum and characteristics of the JNU533-derived bacteriocin. Results confirmed that the JNU533-derived bacteriocin inhibited the growth of lactic acid bacteria. The size of the bacteriocin was approximately 4.9 kDa, and it was heat- and pH-stable under various temperature and pH conditions. Furthermore, the possibility of using JNU533 as a starter culture in the manufacturing of fermented dairy products was assessed. A single colony of JNU533 was inoculated into 10% skim milk containing 0.5% glucose to investigate its characteristics in milk culture. The decrease in the pH was similar to that elicited by Lactobacillus delbrueckii subsp. bulgaricus. Furthermore, the results confirmed that JNU533 inhibited the growth of various bacteria and could be used as a milk fermentation starter. This study highlights the characteristics of the bacteriocin produced by JNU533 and the growth features of this strain in a skim milk medium.

• KSBB Journal
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• v.8 no.5
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• pp.446-451
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• 1993

In ethanol fermentation, by-products such as glycerol, acetic acid and lactic acid are produced along with ethanol. The effects of culture conditions on cell growth ethanol production and by-products biosynthesis were investigated in ethanol fermentation using S. cerevisiae. With increasing aeration rate or yeast extract concentration, ethanol and by-products biosynthesis decreased while final cell mass increased. With increasing glucose concentration or decreasing temperature, final cell mass, ethanol and by-products concentrations all increased. The optimal pH for the cell growth, ethanol and by-products productions was found to be pH 4.5. By-products biosynthesis was found, in general, to proceed with the ethanol biosynthesis. The results can be applied for the optimization of ethanol fermentation and for the recovery and purification of ethanol from the culture broth.

• Journal of Life Science
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• v.8 no.1
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• pp.85-90
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• 1998

Pseudomonas sp. KH2-2 had the denitrifying ability adn was isolated from the denitrifier consortium in order to remove nitrogen compounds from waste water in aquaculture system. When this strain was reached stationary phase, it has the maxium denitrification activity. Denitrification activity of the isolated strain was shown the growth associated pattern. Optimal temperature for cell growth and denitrification activity was 40$\circ$C and optimal pH was 7.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.171-178
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• 1996

This experiment was performed with the purpose of finding out the effect of simulated acid rain at various pH levels on the morphology and enzyme of Perilla frutescens var. japonica hara. The pH levels of simulated acid rain ranged from pH 2.0 to pH 6.0. The experiment showed the anion concentrations in the order of $SO_4^{2-}$, Cl^-$, $NO_3^-$, and $F^-$, $SO_4^{-2}$ was found out to be the main factor which contributed to the rainwater acidification. A general decrease of growth in Perilla frutescens var. japonica hara growth was shown with the decreas of pH concentration. As acidity increases a definite reduction in the rates of germination, heigth of plant, malate dehydrogenase, and 6-phosphogluconate dehydrogenase was ovserved, but the density of spots on the leaf apex was increased.

• Journal of Ginseng Research
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• v.33 no.2
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• pp.143-148
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• 2009

This study was carried out to detennine the optimal submerged culture conditions for the growth increase of ginseng adventitious roots containing germanium by means of a fractional factorial design with four factors and three levels, using the response surface methodology (RSM). The ginseng (Panax ginseng CA. Meyer) adventitious roots were induced by plant growth regulators and cultured in a liquid SH medium. The effects of various $GeO_2$ and phosphoric acid ($H_3P0_4$) concentrations in the medium, $GeO_2$ addition time and the pH of the medium on the fresh weight of the ginseng adventitious roots were investigated. The optimum pH of the medium and the phosphoric acid concentration detennined by the partial differentiation of the model equation were 4.7 and 6.0 roM, respectively. The predicted optimal $GeO_2$ concentration was 10 ppm and the $GeO_2$ addition time did not affect the growth of ginseng adventitious roots. Under these conditions, the growth of the ginseng adventitious root containing germanium was predicted to be 2.47 g.

• Journal of Life Science
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• v.19 no.4
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• pp.457-461
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• 2009

We optimized dextranase culture conditions by batch fermentation using Lipomyces starkeyi KCTC 17343. Furthermore, dextranase was purified by an ultra-membrane, and then dextran hydrolyzates were characterized. Cell growth and dextranase production varied depending on the initial culture pH and temperature. The conditions of optimal dextranase production were met in a pH range of 4-5 and temperature between $25-30^{\circ}C$. At optimal fermentation conditions, total enzyme activity and specific enzyme activity were about 4.85 IU/ml and 0.79 IU/g cells, respectively. The specific growth rate was examined to be $0.076\;hr^{-1}$. The production of dextranase in culture broth was very stably maintained after mid-log phase of growth. The enzyme hydrolyzed dextran into DP (degree of polymerization) 2 to 8 oligodextran series. Analysis of the composition of hydrolysates suggested that the enzyme produced is an endo-dextranase.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1307-1313
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• 2002

This study was performed to investigate the single and combined effect of concentrations of garlic juice according to the pH and temperature on the growth of Salmonella enteritidis in brain heart infusion broth, and to develope Response surface model for the effect of concentrations of garlic extract. The results of electric conductibility of Salmonella enteritidis growing in the range of incubation temperature ($25~42^{\circ}C$), pH (5.5~9.0) and concentration of garlic Juice (0~0.8%) showed that a badge with high temperature had low D.T.value and concentration of garlic extract were significantly correlated with D.T.value (p<0.01). Growth of Salmonella enteritidis in the condition of $37^{\circ}C$ and pH 7.0 presented the lowest D.T.value.