• The Korean Journal of Ecology
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• 제21권3호
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• pp.277-282
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• 1998

The microbial degradation of $poly-{\beta}-hydroxybutyrate$ (PHB) films was studied in soil microco는 incubated at a constant temperature of 2, 10, 20, 30 and $40^{\circ}C$ for up to 49 days. The degradation rate measured through loss of weight was enhanced by incubation at a higher temperature. At the soil temperature $40^{\circ}C$, $poly-{\beta}-hydroxybutyrate$ was rapidly degraded at a decay rate of 3.5% weight loss per day. The degradation of $poly-{\beta}-hydroxybutyrate$ did not affected significantly the chemical properties of soils such as pH and electric conductivity. However, microbial activity of soil in terms of dehydrogenase activity was increased by the degradation of $poly-{\beta}-hydroxybutyrate$.

• 한국미생물·생명공학회지
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• 제23권5호
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• pp.588-592
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• 1995

Fed-batch fermentation was used to produce the high concentrations of poly-$\beta $-hydroxybutyrate (PHB) and poly-$\beta $-(hydroxybutyrate-co-hydroxyvalerate) (PHB/V). Specific growth rate ($\mu $), yield of cell from glucose (Y$_{x/s}$) were calculated from the two samples in 3 to 5 hours of interval and they were reflected on the determination of glucose feeding rate to maintain the glucose concentration at around 10 g/l in the culture broth. PHB was accumulated after the nitrogen became limited at 60 g/l of dry cell weight by changing ammonia water to 4N-NaOH solution. As results, the final dry cell weight (DCW) of 170 g/l, PHB of 115 g/l were obtained in 50 hours and the overall productivity was 2.4 g/l$\cdot $h. After PHB accumulation, cosubstrate of glucose and propionic acid (PA) was fed to accumulate PHB/V. But, PA feeding rate was decreased from 3 g/l$\cdot $h to 1 g/l$\cdot $h to prevent PA from accumulating to high level in the broth, which is very inhibitory to the cells. As results, DCW, PHB and PHV were 147.5 g/l, 90 g/l and 8 mole % of hydroxyvalerate, respectively.

• Journal of the Korean Data and Information Science Society
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• 제26권3호
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• pp.687-693
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• 2015

본 연구는 젖소의 검정기록, 378,086개를 이용하여 케토시스 진단 지시형질로 이용되는 유량내 아세톤과 ${\beta}$-히드록시부틸산의 함량에 영향을 미치는 환경요인을 분석하였다. 형질별 목장, 비유단계, 산차, 착유시간 및 월령에 대한 유의성 검정 결과 모든 요인들에서 고도의 유의성 (p < 0.01)이 나타났으며, 가장 큰 환경요인은 비유단계였다. 1회 착유량, 아세톤과 ${\beta}$-히드록시부틸산의 함량에 대한 월령의 1차 회귀계수는 모두 정 (+)의 관계, 2차 회귀계수는 부 (-)의 관계를 나타내었으며, 비유 2단계 (36~65일) 비유량의 최소자승평균은 19.06kg으로 비유말기에 비하여 6.51kg 높았다. 아세톤과 ${\beta}$-히드록시부틸산의 함량에 대한 최소자승평균은 비유 1단계 (5~35일)에서 각각 0.1929mM/L과 0.0742mM/L로 가장 높았으며, 착유일수에 따라 감소하다가 비유말기 소폭 증가하는 경향을 나타내었다. 1산에 대한 아세톤과 ${\beta}$-히드록시부틸산의 함량의 최소자승평균은 각각 0.1414mM/L과 0.0522mM/L로 2차산 이상의 평균보다 높았으며, 오후착유에 대한 아세톤과 ${\beta}$-히드록시부틸산의 함량의 최소자승평균이 각각 0.1372mM/L과 0.0534mM/L로 오전착유보다 일괄적으로 높게 나타났다.

• Journal of Microbiology and Biotechnology
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• 제7권5호
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• pp.360-362
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• 1997

A transposon Tn5 mutant of Rhodobacter sphaeroides 2.4.1 was isolated for its impaired ability of growth on minimal medium containing ${\beta}$-hydroxybutyric acid as a sole carbon source. The mutant, R. sphaeroides S7 showed approximately 6-fold decrease in ${\beta}$-hydroxybutyrate dehydrogenase activity compared with that of wild type. In R. sphaeroides S7 the Tn5 was located in DNA region corresponding to a 4.2-kb EcoRI DNA fragment of R. sphaeroides 2.4.1 chromosome.

• 자연과학논문집
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• 제9권1호
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• pp.53-56
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• 1997

Cyanobacteria Chlorogloea fritschii를 여러 생장조건(인산 충분 혹은 결핍)에서 배양한 후 poly-$\beta$-hydroxybutyrate(PHB)를 추출하여 그의 구조를 적외선 분광법에 의해 분석하였다. 이들은 공통적으로 C=O의 신축 진동에 의한 1700-1800 $cm^-1$영역에서 대단히 강한 흡수 피이크를 나타내고 또한 2900$cm^-1$에서 C-H의 비대칭 및 대칭 신축 진동흡수 피이크를 나타냄으로써 PHB의 특징을 잘 나타내고 있었다. 그러나 생장조건에 따라 C-H의 신축 진동흡수 피이크 세기에 변화를 관측할 수 있었으며 인산 결핍 생장조건에서 C-H의 신축 진동흡수 피이크의 세기는 나머지 피이크에 비해 증가된 양상을 나타냄으로 인산의 공급여하에 따른 PHB구조의 변화를 시사하였다.

• Journal of Microbiology and Biotechnology
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• 제6권6호
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• pp.425-431
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• 1996

The enzymatic characteristics of Alcaligenes latus were investigated by measuring the variations of various enzyme activities related to biosynthesis and degradation of poly-${\beta}$-hydroxybutyrate (PHB) during cultivation. All PHB biosynthetic enzymes, ${\beta}$-ketothiolase, acetoacetyl-CoA reductase, and PHB synthase, were activated gradually at the PHB accumulation stage, and the PHB synthase showed the highest value among three enzymes. This indicates that the rate of PHB biosynthesis is mainly controlled by either ${\beta}$-ketothiolase or acetoacetyl-CoA reductase rather than PHB synthase. The enzymatic activities related to the degradation of PHB were also measured, and the degradation of PHB was controlled by the activity of PHB depolymerase. The effect of supplements of metabolic regulators, citrate and tyrosine, was also investigated, and the activity of glucose-6-phosphate dehydrogenase was increased by metabolic regulators, especially by tyrosine. The activities of ${\beta}$-ketothiolase and acetoacetyl-CoA reductase were also activated by citrate and tyrosine, while the activity of PHB depolymerase was depressed. The increased rate and yield of PHB biosynthesis by metabolic regulators may be due to the increment of acetyl-CoA concentration either by the repression of the TCA cycle by citrate through product inhibition or by the activation of sucrose metabolism by the supplemented tyrosine.

• Journal of Microbiology and Biotechnology
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• 제5권5호
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• pp.292-296
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• 1995

Production of poly($\beta$-hydroxybutyrate-co-$\beta$-hydroxyvalerate)[poly(HB-co-HV) from glucose and propionic acid was studied in a two-stage fed-batch fermentation using Alcaligenes eutrophus NCIMB 11599. When either glucose became sufficient or the feeding rate of propionic acid decreased, production of poly(HB-co-HV) increased but concomitantly resulted in a reduced fraction of HV. During the copolymer accumulation stage, the specific production rate of hydroxyvalerate (HV) increased up to 0.013 (g-HV/g-RCM/h) but it decreased as propionic acid was accumulated. Control of the propionic acid concentration in the medium, therefore, is considered to be one of the most important operating parameters for production of poly(HB-co-HV) with a higher HV fraction. A high titre of poly(HB-co-HV) (85.6 g/I) with HV fraction of 11.4 mol$%$ could be obtained in 50 h by controlling the propionic acid concentration at 1 to 4 g/I.

• 한국미생물·생명공학회지
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• 제19권2호
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• pp.186-192
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• 1991

It is very important to have a good kinetic model which considers the effects of both ammonium and glucose for the control and optimization of the poly-${\beta}$-hydroxybutyrate (PHB) fermentation. A kinetic model for the growth of Alcaligenes eutrophus and the biosynthesis of PHB under both ammonium and glucose limitation was proposed. Growth rate of residual biomass was expressed as a function of concentrations of residual biomass, glucose and ammonium having glucose inhibition. PHB production rate was expressed as a function of concentrations of residual biomass, glucose, ammonium and PHB content having ammonium and product inhibitions. Novel approaches were made to estimate the parameters in the model equations which considered two limiting substrates. Model parameters were evaluated by graphical and simplex methods. The proposed kinetic model fitted the data very well.

• 한국미생물·생명공학회지
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• 제22권4호
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• pp.401-406
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• 1994

The medium compositions of Alcaligenes eutrophus were optimized for increasing PHB productivity. It is very important to optimize the concentrations of inorganic salts and trace eleme- nts as well as carbon and nitrogen sources to maximize cell growth rate and productivity. The fed-batch culture of Alcaligenes eutrophus by dual feeding of ammonia water and glucose under optimized initial medium concentrations was carried out. Glucose was fed manually according to glucose consumption rate and ammonia water by pH-stat. The final cell concentrations and PHB content in 30 hours were 122 g/l and 65% of dry cell weight(yielding 79 g of PHB/l), respectively and 2.64 g/l/hr of PHB production rate was obtained.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.175-178
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• 2000

Biodegradability of the $poly({\beta}-hydroxybutyrate-co-3 -hydroxyvalerate)$ [PHB/V] containing 0, 10 and 15mol% hydroxyvalerate [HV] was studied. Bioderadability of PHB/V was evaluated at $30^{\circ}C$ for 58 days and $55^{\circ}C$ for 33 days by monitoring the time-dependent changes in weight loss(erosion) of aerobic conditions in a temperature-controlled microcosms containing the earthworm cast($30^{\circ}C$) and compost ($55^{\circ}C$). It was found that PHB/V biodegradability occurred with increasing HV monomer concentration from 0 mol% to 15 mol%.