• 미생물과산업
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• 제26권2호
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• pp.2-12
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• 2000

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 1998년도 제38회 춘계학술발표대회
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• pp.46.1-46.1
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• 1998

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.563-563
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• 2003

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.609-610
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• 2003

• Environmental Engineering Research
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• 제20권3호
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• pp.246-253
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• 2015

The effects of carbon-to-nitrogen (C/N) ratio in simulated rice straw hydrolysates using glucose and ammonium chloride on polyhydroxyalkanoates (PHA) accumulation by Cupriavidus necator was investigated. In general, PHA accumulation rate was higher under higher degrees of N-deficient conditions (e.g., C/N ratio of 360:1) than lower degrees of N-deficient conditions (e.g., C/N ratio of 3.6:1 and 36:1). Also, the most PHA accumulation was observed during the first 12 h after the PHA accumulation initiation. This study showed that the similar PHA accumulation could be achieved by using different accumulation periods depending on C/N ratios. N source presence was important for new cell production, supported by approximately ten times greater PHA accumulation under the N-deficient condition ($NH_4Cl$ 0.01 g/L) than the N-free (without $NH_4Cl$) condition after 96 h. C/N ratio of the rice straw hydrolysate was approximately 160:1, based on the glucose content, and this accumulated $0.36{\pm}0.0033g/L$ PHA with PHA content of $21{\pm}3.1%$ after 12 h. Since external C or N source addition for C/N ratio adjustment increases production cost, an appropriate accumulation period may be used for PHA accumulation from organic wastes, based on the PHA accumulation patterns observed at various C/N ratios and C and N concentrations.

• KSBB Journal
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• 제29권4호
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• pp.244-249
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• 2014

Biosynthesis pathway of medium-chain-length (MCL) polyhydroxyalkanoates (PHA) from fatty acid ${\beta}$-oxidation pathway was constructed in recombinant Escherichia coli by introducing the Pseudomonas sp. 61-3 PHA synthase gene (phaC2) and the maoC genes from Pseudomonas putida, Sinorhizobium meliloti, and Ralstonia eutropha. The metabolic link between fatty acid ${\beta}$-oxidation pathway and PHA biosynthesis pathway was constructed by MaoC, which is homologous to P. aeruginosa (R)-specific enoyl-CoA hydratase (PhaJ1). When the E. coli W3110 strains expressing the phaC2 gene and one of the maoC genes from P. putida, Sinorhizobium meliloti, and Ralstonia eutropha were cultured in LB medium containing 2 g/L of sodium decanoate as a carbon source, MCL-PHA that mainly consists of 3-hydroxyhexanoate (3HHx), 3-hydroxyoctanoate (3HO) and 3-hydroxydecanoate (3HD), was produced. The monomer composition of PHA and PHA contents varied depending on MaoC employed for the production of PHA. The highest PHA content of 18.7 wt% was achieved in recombinant E. coli W3110 expressing the phaC2 gene and the P. putida maoC gene. These results suggest that MCL-PHA biosynthesis pathway can be constructed in recombinant E. coli strains from the b-oxidation pathway by employing MaoC able to supply (R)-3-hydroxyacyl-CoA, the substrate of PHA synthase.

• 미생물학회지
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• 제36권2호
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• pp.84-90
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• 2000

Psudomonas sp. RY-1이 생성하는 extracellular depolymerase system을 이용하여 단위체의 결가지에 서로 다른 탄소 길이와 불포와기를 함유하는 medium-chain-length polyhdroxyalkanoates (MCL-PHAs)의 생분해도를 시럼실 조건에서 조사하였다. 생분애도는 평파내지에서의 clear zone 형성, 효소 처리에 의한 고분자 현탁액의 탁도 감소 및 호흡량의 경시적 변화로 측정하였다. Pseudomonas sp. RY-1은 MCL-PHA depolymerase의 생성을 통하여 조사된 모든 종류의 MCl-PHAs를 분해할 수 있었으나, 이 효소의 생성은 쉽게 이용될수 있는 이차기질에 의해 저해받는 것으로 나타났다. MCl-PHAs의 분해율이 단위체의 탄소수가 홀수개로 구성된 고분자에 비하여 보다 높았다. 곁가지에 분포화기를 함유한 MCl-PHAs는 불포화기를 갖지 아니하는 고분자에 비하여 분해가 빠르게 이루어졌으며, 이들의 분해는 고분자의 결정화도와 밀접한 관련이 있는 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제24권1호
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• pp.59-69
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• 2014

One of the major challenges in metabolic engineering for enhanced synthesis of value-added chemicals is to design and develop new strains that can be translated into well-controlled fermentation processes using bioreactors. The aim of this study was to assess the influence of various fed-batch strategies in the performance of metabolically engineered Pseudomonas putida strains, ${\Delta}gcd$ and ${\Delta}gcd-pgl$, for improving production of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) using glucose as the only carbon source. First we developed a fed-batch process that comprised an initial phase of biomass accumulation based on an exponential feeding carbon-limited strategy. For the mcl-PHA accumulation stage, three induction techniques were tested under nitrogen limitation. The substrate-pulse feeding was more efficient than the constant-feeding approach to promote the accumulation of the desirable product. Nonetheless, the most efficient approach for maximum PHA synthesis was the application of a dissolved-oxygen-stat feeding strategy (DO-stat), where P. putida ${\Delta}gcd$ mutant strain showed a final PHA content and specific PHA productivity of 67% and $0.83g{\cdot}l^{-1}{\cdot}h^{-1}$, respectively. To our knowledge, this mcl-PHA titer is the highest value that has been ever reported using glucose as the sole carbon and energy source. Our results also highlighted the effect of different fed-batch strategies upon the extent of realization of the intended metabolic modification of the mutant strains.

• 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.

• 한국미생물·생명공학회지
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• 제32권2호
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• pp.123-127
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• 2004

토양으로부터 oleic acid 를 탄소원으로 이용하여 MCL-PHA의 생산능이 우수한 균주를 분리하여 Pseudomonas sp. MBEL21이라 명명하였다. Pseudomonas sp. MBEL21의 PHA함량을 증가시키기 위하여 여러 가지 필수 영양분의 제한 조건에서 배양한 결과, 인산이 제한된 조건에서 가장 높은 함량의 PHA를 축적하였다. 고농도의 MCL-PHA생산을 위한 Pseudomonas sp. MBEL21의 유가식 배양 전략을 개발하여 28.1 wt％의 함량으로 23 g/L. MCL-PHA를 생산하였다. 또한, 분리된 Pseudomonas sp. MBEL21을 olive oil을 탄소원으로 이용하여 배양한 결과 9.3 wt％의 PHA가 축적되어졌으며, MCL-hydroxyalkanoate와 함께 3-hyoxy-butyrate 의 단량체들로 이루어진 PHA가 확인되어졌다. 이러한 결과들은 분리된 신규 Pseudomonas sp. MBEL21이 저가의 olive oil로부터 생분해성 탄성체의 응용분야를 갖는 MCL-PHA를 효율적으로 생산할 수 있다는 것을 보여준다.