• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.237-240
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• 2000

회분식 발효를 실시하여 균주의 최적 발효조건을 구하여 세포 재순환식 연속 발효 공정에 적용한 결과, CSL의 최적 함량은 2.5%로 나타났으며, 수율과 생산성은 각각 0.80g total acid/g glucose, 0.26g total acid/L/h이였다. 연속 발효 결과, 최대 생산물 생산성은 희석률 0.2/h에서 3.32g organic acid/L/h을 얻었다. 최적 추출시스템은 30%w/w TOA/MIBK로 나타났으며, Membrane Contactor을 이용한 추출에서는 수용액상의 200ml/min, 추출상은 100ml/min의 유량을 갖는 Counter-current가 최적 조건임을 확인했고, 또한 수용액상과 추출상의 접촉 부피비는 2:1이 여러 가지 요인을 고려했을 때 최적 조건임을 확인했다. 실제 발효를 통해 생성된 유기산의 추출은 1:1의 부피비로 counter-current로 접촉시켰을 때 Acetic acid 가 56% Propionic acid가 72.41%의 추출력을 얻을 수 있었다.

• 한국해양바이오학회지
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• 제10권1호
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• pp.18-25
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• 2018

Chlorella is quantitatively and qualitatively high in protein with balanced essential amino acid profiles, vitamins and minerals. ${\gamma}-Aminobutyric$ acid (GABA) is broadly distributed in nature and fulfills multi-physiological functions including effect such as a health-promoting functional compound. To improve the GABA production, Chlorella protothecoides were grown through the modified mixtrophic culture medium containing 2L of sterilized bristol medium with 0.01% urea and 4.0% glucose in a 5L fermenter. The results showed that nineteen kinds of amino acid including GABA at C. protothecoides sample were analyzed using high performance liquid chromatography (HPLC). Glutamic acid in total concentration (%) of amino acid is the most abundant amino acid (33.10%), followed by alanine (20.48%) and GABA (17.48%). Three amino acids including GABA were responsible for more than 70% total concentration in C. protothecoides sample including eight essential and nine non-essential amino acids: aspartic acid, asparagine, serine, glutamine, histidine, glycine, threonine, arginine, tyrosine, valine, methionine, tryptophan, phenylalanine, isoleucine, leucine, lysine. As a result of this experiment, it is expected that Chlorella will be developed to a critical product having high value as, GABA, functional food materials.

• Journal of Microbiology
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• 제37권4호
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• pp.200-205
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• 1999

7-Aminocephalosporanic acid (7-ACA) is the initial compound in preparation of cephalosporin antibiotics widely used in clinical treatment. Bacteria producing glutaryl 7-ACA acylase, which convert cephalosporin C to 7-ACA, has been screened in soil samples. A bacterial strain exhibiting high glutaryl 7-ACA acylase activity, designated KAC-1, was isolated and identified as a strain of Pseudomonas diminuta by characterizing its morphological and physiological properties. The screening procedures include culturing on enrichment media containing glutaric acid, glutamate, and glutaryl 7-aminocephalosporanic acid as selective carbon sources. To enhance enzyme production, optimal cultivation conditions were investigated. This strain grew optimally at pH 7 to 9 and in temperatures of 20 to 40 C, but acylase production was higher when the strain was grown at 25 C. Glutaric acid, glutamate and glucos also acted as inducers for acylase production. In a jar fermenter culture, P. diminuta KAC-1 produce acylase in a growth-associated manner. The substrate specificity of KAC-1 acylase by cell extract showed that this enzyme had specificity toward glutaryl 7-ACA, glutaryl 7-ADCA, but not cephalosporin C.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1310-1317
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• 2004

The extracellular production of 5-aminolevulinic acid (ALA) by recombinant E. coli BL21 harboring a fusion gene hemA was investigated in a fermenter. For this purpose, the effects of various physiological factors, such as isopropylthio­$\beta$-D-galactopyranoside (IPTG) concentrations and the time of induction, on enzyme activity were studied. Optimum concentrations of glycine and succinic acid were found to be 30 mM and 90 mM, respectively. When the cells were permitted to grow for 2 h prior to the addition of 0.1 mM IPTG, the activity of ALA synthase was higher than when IPTG was initially added. A 36-fold increase in the activity was observed with only 0.1 mM IPTG added. The pH of the medium also influenced the ALA synthase activity with the maximal activity occurring at pH 6.5. In recombinant E. coli extracts, the repeated addition of glycine and D-glucose increased the production of ALA and the inhibited intracellular ALA dehydratase activity, with up to 32 mM ALA being produced in the cultivation.

• 한국식품영양과학회지
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• 제34권6호
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• pp.899-903
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• 2005

1-octen-3-ol은 버섯향의 성분 중 가장 중요한 방향 물질이다 소비자의 천연 버섯향에 대한 선호도가 상승함에 따라 유기합성으로 만들어지는 광활성 이성질체를 포함하고 있는 ($\pm$)-1-octen-3-ol와 다르게 더 강한 향의 강도를 갖는 천연 광활성의 (-)-1-octen-3-ol 생산에 대한 연구가 필요하다. (-)-1-octen-3-ol은 호기성 상태에서 시장에서 구입한 버섯으로 추출된 lipoxygenase(LOX)와 hydroperoxide Lyase(HPOL)을 이용하여 생합성되었다 $75\%$이상의 linoleic acid를 포함하고 있는 경북 의성 에서 생산된 홍화유는 lipase를 이용하여 가수분해하였다. 가수분해된 linoleic acid는 LOX에 의하여 광활성을 지닌 10-hydroperoxy linoleic acid로 생물전환되었다. 10-hydroxyperoxide은 HPOL에 의해 (-)-1 octen-3-ol로 분해되었다. (-)-1-octen-3-ol을 상업적으로생산하기 위하여 5-liter jar fermenter와 충남 부여에서 수확된 Agaricus bisporus 자실체를 이용하여 개발되었다. (-)-1-octen-3-ol은 $4^{\circ}$C, pH 6.5, 800 rpm에서 최대 748 mg의 (-)-1-octen-3-ol(버섯 kg 당)이 생물전환되었다.

• KSBB Journal
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• 제18권6호
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• pp.473-478
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• 2003

본 연구의 목적은 메탄을 최대로 발생시킬 수 있는 최적조건을 탐색하는데 있다. 탐색한 최적조건 인자로는 온도, pH, 탄소원, 그리고 질소원이며, 메탄 발생에 영향을 주는 저해제에 대해서도 조사하였다. 결과적으로, 온도는 3$0^{\circ}C$, pH는 중성영역, 탄소원은 methanol, 질소원은 NH$_4$Cl에서 최대의 메탄을 얻을 수 있었으며, 메탄 생성에 대한 저해재의 영향을 조사한 결과 10 mM 미만의 극소량이라도 2-bromoethanesulfonic acid가 존재할 경우 메탄 발생량이 감소하는 결과를 보였다. 메탄 발생에 대한 pH 변화를 조사해 본 결과, pH가 7.5에서 6.5로 내려가는 동안에는 메탄 발생량이 증가하였으나, 6.5에서 6.0으로 변화되면서는 메탄 발생량이 감소하였다. 따라서 pH 변화를 실시간으로 측정하여 상분리 발효를 적용하면 최적 메탄 생성 조건을 유지할 수 있을 것으로 사료된다. 또한 메탄 발생 시 배지 내에 생성되는 유기산을 측정해 본 결과 생성된 유기산 중 formic acid가 0.1M로 최대량을 보였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.121-124
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• 2000

본 연구의 목적은 식품부산물로부터 유기산 생산 및 분리 농축에 있다. 회분식 발효를 실시하여 균주의 최적 발효조건을 구하여 세포 재순환식 연속 발효공정에 적용한 결과, CSL의 최적 함량은 2.5%로 나타났으며 수율과 생산성은 각각 0.80g total acid/g glucose, 0.26g total acid/L/h로 향상 되었다. 세포 재순환식 연속발효 결과, 최대 유기산 생산성은 희석률 0.2/h에서 3.32g organic acid/L/h로 회분식 발효와 비교해 볼 때 최대 생산성으로는 13배, 세포량으로는 22배 증가한 것으로 나타났다. 또한, 최적 추출시스템은 30%w/w TOA/MIBK로 나타났으며, 발효액내의 유기산을 약 90%까지 분리 및 농축할 수 있음을 확인하였다.

• 한국환경보건학회지
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• 제31권4호
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• pp.294-300
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• 2005

Food waste can be a valuable carbon source in biological nutrient removal (BNR) systems because of high C/N and C/P ratios. However, food waste should be pretreated to promote its hydrolysis rate because hydrolysis reaction would be a rate-limiting step. This study investigates the influence of the enzymatic pretreatment on acid fermentation of food waste. Solubilization of particulate matter in food waste by using commercial enzymes was examined. The acidification efficiency and the volatile fatty acids (VFAs) production potential of enzymatically pretreated food waste were also examined. The highest volatile suspended solids (VSS) reduction was obtained with an enzyme mixture ratio of 1:2:1 of carbohydrase:protease:lipase. An optimum enzyme dosage for solubilization of food waste was $0.1\%$(V/V) with the enzyme mixture ratio of 1:2:1. In the acid fermentation of enzymatically pretreated food waste, $0.1\%$(V/V) enzyme mixture dosage for pretreatment result in the maximum VFAs production and the best VFAs fraction in soluble COD(SCOD). The VFAs production at this addition level was 3.3 times higher than that of no-enzyme added fermenter. The dominant VFAs present was n-butyrate followed by acetate.

• Journal of Microbiology and Biotechnology
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• 제34권4호
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• pp.978-984
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• 2024

Genome-scale metabolic model (GEM) can be used to simulate cellular metabolic phenotypes under various environmental or genetic conditions. This study utilized the GEM to observe the internal metabolic fluxes of recombinant Escherichia coli producing gamma-aminobutyric acid (GABA). Recombinant E. coli was cultivated in a fermenter under three conditions: pH 7, pH 5, and additional succinic acids. External fluxes were calculated from cultivation results, and internal fluxes were calculated through flux optimization. Based on the internal flux analysis, glycolysis and pentose phosphate pathways were repressed under cultivation at pH 5, even though glutamate dehydrogenase increased GABA production. Notably, this repression was halted by adding succinic acid. Furthermore, proper sucA repression is a promising target for developing strains more capable of producing GABA.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.91-94
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• 2002

Arachidonic acid is a polyunsaturated fatty acid(PUFA) containing twenty carbon atoms with four double bonds. The family of w-6 PUFA, including arachidonic acid as well as r-linoleic acid, was served as intermediates in the formation of several key prostaglandin and leukotrienes. Several fungal strains of the genus Mortierella accumulate high amounts of arachidonic acid. In this study experiments were carried out to optimize the culture conditions for the mass production of fungus Mortierella alpina DSA -12 and lipid production with high proportion of polyunsaturated fatty acids, especially arachidonic acid. The batch culture was carried out in 500 L fermenter containing 50 g/L glucose, 18 g/L corn-steep powder and 100 mg/L MnS04 under $25^{\circ}C$, aeration rate of 0.5 vvm and agitation speed of 200 rpm without pH control. As a result, we could be obtained 22 g/L of cell mass with high contents of lipid 12.1 g/L) and arachidonic acid (5.1 g/L) The intermittent fed-batch culture was performed in the medium containing 20 g/L glucose and 10 g/L corn-steep powder. The final glucose concentration was 170 g/L and pH was maintained at 5.5 ${\sim}$ 6.0 by adding 14% ammonia solution. It was shown relatively high cell concentration (70.5 g/L) with high contents of lipid (45.8 g/L) and arachidonic acid 08.3 g/L). Therefore, when compared to batch cultures, the high concentration of arachidonic acid could be obtained by fed-batch culture using M. alpina DSA -12. These results imply that the fed-batch culture of M. alpina DSA -12 was feasible in industrial purpose and could be employed in the commercial production of arachidonic acid.