• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.710-712
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• 2003

A new species of Gram-negative halophilic cartenoid producing bacterium was isolated from the Haeundae Coast, Korea. This strain is non-motile, aerobic, orange-pigmented, rod-shaped, and produced carotenoids, mainly astaxanthin. All the type strains of the genus Paracoccus were compared with this strain using 16S rDNA sequence analysis, fatty acid patterns, and physiological reaction profiles. From the results obtained, this strain is classified as a new species, Paracoccus sp..

• KSBB Journal
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• v.16 no.3
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• pp.290-294
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• 2001

The removal of nitrogen compounds from waste water is essential and is often accomplished by biological process. The denitrifying bacterium, Paracoccus denitrificans (KCTC 2530), was employed to study the characteristics and the denitrification differences of Permeabilized strains and untreated strains. The permeabilization rate increased with increasing toluene concentration, but some part of the toluene contributed to denaturing the datachment of proteins from the plasma membrane. Permeabilized Paracoccus denitrificans had long lag phase and high specific growth rate in cultivation, and showed excellent denitrification characteristic compared with untreated strains. But, in both cases, the denitrification ability was significantly reduced after 4 or 5 denitrifications. It seems that the strains fall into the death phase when the nutrient was exhausted. When the nutrient recovered to its initial level, the denitrification ability also recovered to the normal level. The results obtained were encouraging enough to apply to practical water treatment situation.

• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.59.1-59.1
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• 2007

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• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.1
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• pp.17-22
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• 2004

A bacterial strain WJ-98 found to produce active extracellular keratinase was isolated from the soil of a poultry factory. It was identified as Paracoccus sp. based on its 16S rRNA sequence analysis, morphological and physiological characteristics. The optimal culture conditions for the production of keratinase by Paracoccus sp. WJ-98 were investigated. The optimal medium composition for keratinase production was determined to be 1.0% keratin, 0.05% urea and NaCl, 0.03% K$_2$HPO$_4$, 0.04% KH$_2$PO$_4$, and 0.01% MgCl$_2$$.$6H$_2$O. Optimal initial pH and temperature for the production of keratinase were 7.5 and 37$^{\circ}C$, respectively. The maximum keratinase production of 90 U/mL was reached after 84 h of cultivation under the optimal culturing conditions. The keratinase from Paracoccus sp. WJ-98 was partially purified from a culture broth by using ammonium sulfate precipitation, ion-exchange chromatography on DEAE-cellulose, followed by gel filtration chromatography on Sephadex G-75. Optimum pH and temperature for the enzyme reaction were pH 6.8 and 50$^{\circ}C$, respectively and the enzymes were stable in the pH range from 6.0 to 8.0 and below 50$^{\circ}C$. The enzyme activity was significantly inhibited by EDTA, Zn$\^$2+/ and Hg$\^$2+/. Inquiry into the characteristics of keratinase production from these bacteria may yield useful agricultural feed processing applications.

• KSBB Journal
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• v.20 no.2 s.91
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• pp.100-105
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• 2005

Removal of nitrogen compound from waste water is essential and often accomplished by biological process. Denitrification bacterium, Paracoccus denitrificans (KCTC 2350) is employed to estimate the denitrification ability and the characteristics. In the immobilized biological reactor system, the measurement of absolute amount of active strain in the reactor is comparatively difficult or impossible. In this. study, a reactor was designed with the unwoven texture wrapped peep holed plastic tube to calculate the absolute amount of active strain by comparing the activity of the permeabilized and or immobilized reactor and the free cell reactor The reactor system was continuous stirred tank reactor and the reaction rate of substrate consumption was assumed to satisfy the Michaelis-Menten equation. The effluent concentration of nitrate and nitrite was measured to estimate the apparent parameter of Michaelis-Menten equation. As a result, we found that the amount of immobilized active strain was figured out to be half of the total active strain in the reactor and the time required to be reached in the equilibrium state in the permeabilized and or immobilized reactor system was figured out to be shorter than that of the free cell reactor system.

• Journal of Microbiology and Biotechnology
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• v.7 no.6
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• pp.391-396
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• 1997

Two series of carbon sources, linear primary $C_1$~$C_9$ alcohols and linear $C_2$~$C_{10}$ monocarboxylic acids were tested for PHA synthesis in Paracoccus denitrificans. The results showed that the growth-associated synthesis of PHA could be referred only to the carbon sources with odd number of carbon except methanol. For all carbon sources with even number of carbon, nitrogen limitation was required to induce PHA synthesis in P. denitrificans. Poly(3-hydroxyvalerate)[P(3HV)] homopolymer was synthesized from $C_5$, $C_7$, and $C_9$ while growing in the presence of nitrogen, but the nitrogen depletion in the later growth period incorporated 3-hydroxybutyrate(3HB) unit into the polymer chain. The optimum C/N ratio for P(3HV) homopolymer production was found to be 10 when the strain was grown on 10 ml/l of valeric acid for 96 h. P. denitrificans synthesized P(3HB-co-3HV) copolymers from n-hexanoic and n-octanoic acid. The microstructural characterics of the P(3HB-co-3HV) copolymer from n-propanol was investigated using $^13C$-nuclear magnetic resonance spectroscopy, showing a structural heterogeneity.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1013-1017
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• 2020

Mealybugs (Hemiptera: Coccomorpha: Pseudococcidae) harbor diverse microbial symbionts that play essential roles in host physiology, ecology, and evolution. In this study we aimed to reveal microbial communities associated with two different mealybugs, papaya mealybug (Paracoccus marginatus) and two-tailed mealybug (Ferrisia virgata) collected from the same host plant. Comparative analysis of microbial communities associated with these mealybugs revealed differences that appear to stem from phylogenetic associations and different nutritional requirements. This first report on both bacterial and fungal communities associated with these mealybugs provides a preliminary insight on factors affecting the endomicrobial communities.

• Fisheries and Aquatic Sciences
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• v.12 no.1
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• pp.54-59
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• 2009

Carotenoids such as $\beta$-carotene and astaxanthin are used as food colorants, animal feed supplements and for nutritional and cosmetic purposes. In a previous study, an astaxanthin biosynthesis gene cluster was isolated from the marine bacterium, Paracoccus haeundaensis. Geranylgeranyl pyrophosphate (GGPP) synthase (CrtE), encoded by the ortE gene, catalyzes the formation of GGPP from farnesyl pyrophosphate (FPP), which is an essential enzyme for the biosynthesis of carotenoids in early steps. In order to study the biochemical and enzymatic characteristics of this important enzyme, a large quantity of purified GGPP synthase is required. To overproduce GGPP synthase, the crtE gene was subcloned into a pET-44a(+) expression vector and transformed into the Escherichia coli BL21(DE3) codon plus cell. Transformants harboring the crtE gene were cultured and the crtE gene was over-expressed. The expressed protein was purified to homogeneity by affinity chromatography and applied to study its biochemical properties and molecular characteristics.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.144-148
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• 2013

Lycopene cyclase converts lycopene to ${\beta}$-carotene by catalyzing the formation of two beta-rings at each end of the linear carotene structure. This reaction takes place as a two-step reaction in which both sides of of the lycopene molecule are cyclized into ${\beta}$-carotene rings via the monocyclic ${\gamma}$-carotene as an intermediate. The crtY gene coding for lycopene cyclase from Paracoccus haeundaensis consists of 1,158 base pairs encoding 386 amino acids residues. An expression plasmid containing the crtY gene (pET44a-CrtY) was constructed and expressed in Escherichia coli, and produced a recombinant protein of approximately 43 kDa, corresponding to the molecular mass of lycopene cyclase. The expressed protein was purified to homogeneity by His-tag affinity chromatography and showed enzymatic activity corresponding to lycopene cyclase. We also determined the lycopene substrate specificity and NADPH cofactor requirements of the purified protein. The $K_m$ values for lycopene and NADPH were 3.5 ${\mu}M$ and 2 mM, respectively. The results obtained from this study will provide a wider base of knowledge on the enzyme characterization of lycopene cyclase at the molecular level.

• KSBB Journal
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• v.24 no.3
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• pp.321-326
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• 2009

This study was to optimize the medium components for astaxanthin production in Paracoccus sp. through surface response methodology. A screening test was first conducted on 5 medium components using a Plackett-Burman design, from which $MgSO_4$ and yeast extract were identified as the significant factors affecting astaxanthin production. These significant factors were optimized by central composite design of experiments and response surface methodology, as 2.83 g/L $MgSO_4$ and 7.02 g/L yeast extract, respectively. The expected astaxanthin concentration with these optimized medium compositions were 0.925 mg/L. In flask culture, the experimentally obtained concentration of astaxantin was 1.021 mg/L, where it had been 0.4 mg/L before optimization.