• 한국동물학회:학술대회논문집
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• 한국동물학회 1996년도 한국생물과학협회 국제학술대회
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• pp.195.2-195
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• 1996

acs gene cloning was constructed by subcloning the 2.2-kb MunI-MunI restriction fragment of 638 and 639 which include acs gene from the kohara phage into the unique EcoRI site of pUC18 and pJM9131 containing the PHA biosynthesis genes. Then recombinant E. coli fadRatoC(Con) mutants containing the polyhydroxyalkanoate(PHA) biosynthesis genes are able to incoporate s significant levels of 3-hydroxyvalerate (3HV) into the copolymer [P(3HB-co-3HV)]. Quantitative determination of PHB and P(3HB-co-3HV) was performed by gas-chromatographic analysis of extracts obtained from methanolysis of lyophilized cells.

• KSBB Journal
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• 제29권6호
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• pp.399-404
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• 2014

Production of biodegradable polymer polyhydroxyalkanoates (PHAs) from industrial wastes exhibits several advantages such as recycle of waste and the production of high valuable products. To this end, this study aimed at isolating from the sewage treatment plant a PHA producing bacterium capable of utilizing wastes generated from biodiesel and food industries. A Bacillus cereus strain capable of producing poly(3-hydroxybutyrate) [P(3HB)] was isolated, which was followed by confirmation of P(3HB) accumulation by gas-chromatographic analyses. Then, the effects of nutrient limitation on P(3HB) production by B. cereus was first examined. Cells cultured in a minimal medium under the limitation of nitrogen, potassium and sulfur suggested that nitrogen limitation allows the highest P(3HB) accumulation. Next, production of P(3HB) was examined from both waste of biodiesel production (crude glycerol) and waste from food industry (spent coffee grounds). Cells cultured in nitrogen-limited minimal medium supplemented crude glycerol and waste spent coffee grounds extract accumulated P(3HB) to the contents of 2.4% and 1.0% of DCW. This is the first report demonstrating the capability of B. cereus to produce P(3HB) from waste raw materials such as crude glycerol and spent coffee grounds.

• Journal of Microbiology and Biotechnology
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• 제7권6호
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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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• 제32권1호
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• pp.110-116
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• 2022

Polyhydroxyalkanoates (PHAs) are emerging as alternatives to plastics by replacing fossil fuels with renewable raw substrates. Herein, we present the construction of engineered Escherichia coli strains to produce short-chain-length PHAs (scl-PHAs), including the monomers 4-hydroxyvalerate (4HV) and 3-hydroxyvalerate (3HV) produced from levulinic acid (LA). First, an E. coli strain expressing genes (lvaEDABC) from the LA metabolic pathway of Pseudomonas putida KT2440 was constructed to generate 4HV-CoA and 3HV-CoA. Second, both PhaAB enzymes from Cupriavidus necator H16 were expressed to supply 3-hydroxybutyrate (3HB)-CoA from acetyl-CoA. Finally, PHA synthase (PhaC_Cv) from Chromobacterium violaceum was introduced for the subsequent polymerization of these three monomers. The resulting E. coli strains produced four PHAs (w/w% of dry cell weight): 9.1 wt% P(4HV), 1.7 wt% P(3HV-co-4HV), 24.2 wt% P(3HB-co-4HV), and 35.6 wt% P(3HB-co-3HV-co-4HV).

• 폴리머
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• 제31권3호
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• pp.233-238
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• 2007

Poly(glycolic acid) (PGA)와 poly [(R) -3-hydrokybutyrate] (P3HB) 및 poly(butylenes succinate-co-L-lactate) (PBSL) 복합재료를 체내에서 서로 다른 가수분해속도를 보완하여 저가의 의료용 흡수성 복합재료로 응용하고자 연구하였다. 그 결과 PBSL/PGA와 P3HB/PGA 복합섬유는 인산염 완충용액 중에서 가수분해되는 것이 확인되었으며, PBSL/PGA 복합섬유는 PGA의 분해에 의해 발생된 glycolic acid에 의해 PBSL의 분해가 촉진되는 메카니즘이 확인되었다. PBSL/PGA 복합섬유는 lipase PS가 존재함에 의해 상당히 빠른 가수분해가 발생하는 것이 확인되었으며, 대기중에서는 거의 가수분해가 발생되지 않는 것을 알 수 있었다. P3HB/PGA 복합섬유 역시 대기중에서 적당한 인장강도를 유지하고 있는 것이 확인된 것으로 보아 본 연구를 통하여 이들 복합섬유는 의료용 흡수성 복합재료와 환경 적합재료로서 응용이 가능할 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.847-853
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• 1999

A Pseudomonas sp. strain that is capable of utilizing dicarboxylic acids as a sole carbon source was isolated from activated sludge by using the enrichment culture technique. This organism accumulated polyhydroxyalkanoates (PHAs) with an unusual pattern of monomer units that depends on the carbon sources used. Polyhydroxybutyrate (PHB) homopolyester was synthesized from glucose or small $C_{-even}$ alkanoic acids, such as butyric acid and hexanoic acid. Accumulation of PHB homopolyester was also observed in the cells grown on $C_{-odd}$ dicarboxylic acids, such as heptanedioic acid and nonanedioic acid as the sole carbon sources. In contrast, a copolyester consisting of 6 mol% 3-hydroxybutyrate (3HB) and 94 mol% 3-hydroxyvalerate (3HV) was produced with a PHA content of as much as 36% of the cellular dry matter. This strain produced PHAs consisting both of the short-chain-length (SCL) and the medium-chain-length (MCL) 3-hydroxyacid units when heptanoic acid to undecanoic acid were fed as the sole carbon sources. Most interestingly, polyester consisting of significant amount of relevant fractions, 3HB, 3HV, and 3-hydroxyheptanoate (3HHp), was accumulated from heptanoic acid. According to solvent fractionation experiments, the polymer produced from heptanoic acid was a blend of poly(3HHp) and of a copolyester of 3HB, 3HV, and 3HHp units. The hexane soluble fractions contained only 3HHp units while the hexane-insoluble fractions contained 3HB and 3HV units with a small amount of 3HHp unit. The copolyester was an elastomer with unusual mechanical properties. The maximum elongation ratio of the copolyester was 460% with an ultimate strength of 10 MPa, which was very different from those of poly(3HB-co-3HV) copolyesters having similar compositions produced from other microorganisms.

• KSBB Journal
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• 제13권2호
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• pp.187-194
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• 1998

For mass production of polyhydroxyalkanoates (PHA), high cell density cultures of Alcaligenes eutrophus by fed-batch culture under phosphate-limitation condition has been investigated. PHA accumulation by the regulation by the regulation of initial phosphate concentration could be automatically induced, and high density cell culture above 200 g/L also could be successfully produced. The production of Poly-$\beta$-hydroxybutyrate (PHB) and dry cell weight increased with increasing the initial phosphate concentration. When the initial concentrations of phosphate were in the ranges of 1.5~4.5 g-PO$_4$/L, PHB and dry cell weight obtained were 83~266 g/L and 61~216 g/L, respectively, and PHB productivity was in the ranges of 1.35~3.10 g/L.h. When a mixture of glucose and propionic acid is used as carbon sources, poly(3-hydroxybutyrate-co-poly-3-hydroxyvalerate), P(3HB-co-3HV), could be also successfully produced under phosphate limitation condition. When the mole ratio of propionic acid to glucose in the feeding solution is 0.22, a final dry cell weight of 150 g/L and a P(3-HB-co-3HV) of 90 g/L were produced. Morphological changes and size distribution of PHB granules synthesized in A. eutrophus under phosphate-limitation condition are determined by TEM during the course of fed-batch. Mean granule diameters of PHB produced are in the range of 0.36~0.39 $\mu$m, and mean cell size was elongated from 0.54~0.59 $\mu$m$\times$ 1.3~1.5 $\mu$m to 0.83~0.89 $\mu$m $\times$2.0~2.3 $\mu$m. Phosphate concentration in media did not affect size distribution of PHB granule and cell.

• Macromolecular Research
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• 제14권4호
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• pp.408-415
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• 2006

Temperature-dependent, wide-angle, x-ray diffraction (WAXD) patterns and infrared (IR) spectra were measured for biodegradable poly(3-hydroxybutyrate) (PHB) and its copolymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(HB-co-HHx) (HHx=2.5, 3.4, 10.5, and 12 mol%), in order to explore their crystal and lamellar structure and their pattern of C-H...O=C hydrogen bonding. The WAXD patterns showed that the P(HB-co-HHx) copolymers have the same orthorhombic system as PHB. It was found from the temperature-dependent WAXD measurements of PHB and P(HB-co-HHx) that the a lattice parameter is more enlarged than the b lattice parameter during heating and that only the a lattice parameter shows reversibility during both heating and cooling processes. These observations suggest that an interaction occurs along the a axis in PHB and P(HB-co-HHx). This interaction seems to be due to an intermolecular C-H...O=C hydrogen bonding between the C=O group in one helical structure and the $CH_3$ group in the other helical structure. The x-ray crystallographic data of PHB showed that the distance between the O atom of the C=O group in one helical structure and the H atom of one of the three C-H bonds of the $CH_3$ group in the other helix structure is $2.63{\AA}$, which is significantly shorter than the sum of the van der Waals separation ($2.72{\AA}$). This result and the appearance of the $CH_3$ asymmetric stretching band at $3009 cm^{-1}$ suggest that there is a C-H...O=C hydrogen bond between the C=O group and the $CH_3$ group in PHB and P(HB-co-HHx). The temperature-dependent WAXD and IR measurements revealed that the crystallinity of P(HB-co-HHx) (HHx =10.5 and 12 mol%) decreases gradually from a fairly low temperature, while that of PHB and P(HB-co-HHx) (HHx = 2.5 and 3.5 mol%) remains almost unchanged until just below their melting temperatures. It was also shown from our studies that the weakening of the C-H...O = C interaction starts from just above room temperature and proceeds gradually increasing temperature. It seems that the C-H...O=C hydrogen bonding stabilizes the chain holding in the lamellar structure and affects the thermal behaviour of PHB and its copolymers.

• Journal of Microbiology
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• 제39권1호
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• pp.79-82
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• 2001

The influence of levulinic acid (LA) on the production of copolyester consisting of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) by Ralstonia eutropha was investigated. Addition of LA into the culture medium greatly increased the molar fraction of 3HV in the copolyester, indicating that LA can be utilized as a precursor of 3HV. In shake flask culture, the 3HV content in the copolyester increased from 7 to 75 mol% by adding 0.5 to 4.0 g/L LA to the medium containing fructose syrup as a main carbon source. A maximal copolyester concentration of 3.6 g/L (69% of dry cell weight) was achieved with a 3HV content of 40 mo1% in a jar fermentor culture containing 4.0 g/L of LA. When LA (total concentration, 4 g/L) was added repeatedly into a fermentor culture to maintain its concentration at a low level, the copolyester content and the 3HV yield from LA reached up to 85% of dry cell weight and 5.0 g/g, respectively, which were significantly higher than those when the same concentration of the LA was supplied al1 at once. The present results indicated that LA is more effective than propionate or valerate as a cosubstrate fur the production of copolyesters with varying molar fractions of 3HV by R. eutropha.

• 생명과학회지
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• 제33권3호
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• pp.242-251
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• 2023

마우스 모델을 사용하여, 8주 케톤체(베타-하이드록시뷰티레이트, β-HB)가 지구성 운동 수행능력과 골격근의 단백질 합성 및 분해에 미치는 영향을 조사하였다. 48마리의 수컷 ICR 마우스(8주령)를 무작위로 4개 그룹으로 나누었다: 비운동 통제군(Sed+Con), 비운동+베타-하이드록시뷰티레이트(Sed+β-HB), 운동 통제군(Exe+Con), 운동+베타-하이드록시뷰티레이트(Exe+β-.HB). β-HB 투여를 위해 β-HB를 PBS (150 mg/mL)에 용해시켜 8주 동안 매일 피하 주사(250 mg/kg)하였다. 운동 훈련을 위해 마우스는 8주 동안 20분 트레드밀 달리기 운동 훈련을 주 5일 수행하였다. 훈련은 10° 경사도에서 10 m/min 속도에서 5 min 동안 실시하고 나서, 매 1 min 마다 1 m/min의 속도를 나머지 15 min 동안 증가시켰다. 8주간의 처치 후, 내장 지방량과 골격근량, 혈액 매개변수, 자가포식 및 단백질 합성 마커가 분석되었다. 데이터는 SPSS 21 프로그램을 사용하여 ANOVA (p<0.05)로 분석되었다. Exe+β-HB 그룹의 혈중 젖산 수치는 모든 3개 그룹(Sed+Con, Sed+β-HB 및 Exe+β-HB)보다 유의하게 낮았다(p<0.05). Sed+Con 및 Exe+Con 그룹에 비해, 8주 Exe+β-HB 처치는 최대 달리기 수행 시간(탈진 시간)을 유의하게 증가시켰다(p<0.05). 8주 β-HB 투여는 마우스의 골격근에서 자가포식 유동과 자가포식 관련 단백질을 유의하게 감소시켰다(p<0.05). 반대로, β-HB와 지구력 운동 훈련의 조합된 처치는 단백질 합성(mTOR 신호 및 번역 속도)을 증가시켰다(p<0.05). 8주간의 β-HB 처치와 지구력 운동 훈련은 마우스 골격근에서 지구력 수행능력 증가, 단백질 합성 증가, 단백질 분해 감소 효과를 보여주었다.