• Journal of Microbiology and Biotechnology
• /
• v.25 no.4
• /
• pp.452-458
• /
• 2015

The biocatalytic efficiency of recombinant Corynebacterium glutamicum ATCC 13032 expressing the secondary alcohol dehydrogenase of Micrococcus luteus NCTC2665 was studied. Recombinant C. glutamicum converts ricinoleic acid to a product, identified by gas chromatography/mass spectrometry as 12-ketooleic acid (12-oxo-cis-9-octadecenoic acid). The effects of pH, reaction temperature, and non-ionic detergent on recombinant C. glutamiucm whole cell bioconversion were examined. The determined optimal conditions for production of 12-ketooleic acid are pH 8.0, 35℃, and 0.05 g/l Tween80. Under these conditions, recombinant C. glutamicum produces 3.3 mM 12-ketooleic acid, with a 72% (mol/mol) maximum conversion yield, and 1.1 g/l/h volumetric productivity in 2 h; and 3.9 mM 12-ketooleic acid, with a 74% (mol/mol) maximum conversion yield, and 0.69 g/l/h maximum volumetric productivity in 4 h of fermentation. This study constitutes the first report of significant production of 12-ketooleic acid using a recombinant Corynebacterium glutamicum-based biocatalyst.

• YAKHAK HOEJI
• /
• v.33 no.6
• /
• pp.365-371
• /
• 1989

Microbiological conversion of sterols to 17-ketosteroids has been recognized as a source for commercial preparation of steroidal drugs. In order to develop bacterial strains and process with Brevibacterium lipolyticum IAM 1398 capable of converting cholesterol to 1,4-Androstadiene-3,17-dione (ADD) at about 27% yield, we studied on strain improvement, fermentation condition and whole cell immobilization. By using UV and/or NTG as mutagens, a mutant to convert cholesterol to ADD with higher yield than 60% was selected. Better production of ADD was manifested in the case of maltose used as a supplemental carbon source, and yeast extract or soytone as a nitrogen source. Addition of tween 80 (0.05%) as a surfactant beneficial for increasing the productivity. The optimal initial pH of the medium was 6.5 and optimal culture temperature was $30^{\circ}C$. Whole cell immobilization by using carrageenan, agar, alginate and acrylamide was carried out and the activity of conversion was tested. In the case of carrageenan and agar, immobilized cells were active for at least two cycles of fermentation.

• Archives of Pharmacal Research
• /
• v.3 no.1
• /
• pp.7-12
• /
• 1980

Ampliciline was synthesized from 6-amino-pencillanic acid (6-APA) and D-.alpha. phenylglycine methyl ester by using amplicilin synthesizing enzyme from Peudomonas melanogenum (IAM 1655). The whole cell enzyme was immobilized by entrapping it in the polyacrylamide gel lattices. The polymer used in the enzyme entrapment was made from 150 mg per ml of acrylamide monomer and 8 mg per ml of N, N'-methylenebisacrylamide. About 200 mg/whole cell enzyme was mixed in the polymer for entrapment. The maximal activity retention after immobilization was 56%. The optimal pH values for the whole cell enzyme and the immobilized whole cell enzyme were 6.0 and 5.9, respectively. The optimal temperature for the enzyme activity were the same for both type of preparations. The enzyme stabilities against pH and heat increased for immobilized whole cell enzyme. Immobilized cell was more stable especially in the acidic condition while both type were found to be very suceptible to thermal inactivation at a temperature above 4.deg.C. The kinetic constants obtained from Lineweaver-Burk plot based on two substate reaction mechanism showed somewhat higher value for immobilized whole cell enzyme as compared to the whole cell enzyme : the Km value for 6-APA were 7.0 mM and 12.5 mM while Km values for phenylglycine methyl ester were 4.5 mM and 8.2 mM, respectively. Using the immobilized whole cell enzyme packed in a column reactor, the productivity of ampiciline was studied by varying the flow rate of substrate solution. At the space velocity, SV, 0.14 hr$^{-1}$ the conversion was 45%. Operational stability found in terms of half life was 30 hr at SV = 0.2 hr.

• Korean Journal of Pharmacognosy
• /
• v.24 no.2
• /
• pp.131-139
• /
• 1993

These studies were conducted to investigate the effects of the extracts from Hoelen alba, Alismatis Rhizoma and Atractylodes Rhizoma on the proliferation and differentiation of 3T3-L1 cells. The results were summerized as follows: Hoelen alba and Alismatis Rhizoma extracts inhibited the proliferation of preadipose 3T3-L1 cells. In inductive differentiation, all three extracts inhibited the adipose conversion in 2 days of initial-culture, Atractylodes Rhizoma extract inhibited the adipose conversion in 5 days of final-culture and Hoelen alba and Alismatis Rhizoma inhibited adipose conversion in treatment of whole term of culture. In spontaneous differentiation, Atractylodes Rhizoma extract increased the adipose conversion in 2 days of initial-culture, Hoelen alba and Alismatis Rhizoma increased the adipose conversion in 5 days of final-culture, all three extracts increased adipose conversion in treatment of whole term of culture. The 10% serum of mice treated with each sample did not affect, but the 5% serum of them inhibited the proliferation of 3T3-L1 cells. In inductive differentiation, the 10% serum of them inhibited the adipose conversion in treatment of whole term of culture.

• Journal of the Korean Chemical Society
• /
• v.41 no.9
• /
• pp.483-487
• /
• 1997

The whole cells of Chromobacterium chocolatum was immobilized in the matrix of polyacrylamide and then used for the hydrolysis of dimethyl-cis-1,3-dibenzyl-2-oxoimidazolidine-4,5-dicarboxylate. This hydrolysis yielded the optically active monoester ( > 96% ee) which is useful as an synthetic intermediate of (+)-biotin. We have studied the optimum condition of hydrolysis by using immobilized cells under variable concentration of substrate, reaction time and pH levels. The activity of lipase in immobilized cell was retained for longer than 4 weeks. The best conversion yield of product was obtained when 2 g of wet cell was immobilized and then reacted with 200 mg of substrate at pH 7.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.12
• /
• pp.2076-2086
• /
• 2016

Fungal cytochrome P450 (CYP) enzymes catalyze versatile monooxygenase reactions and play a major role in fungal adaptations owing to their essential roles in the production avoid metabolites critical for pathogenesis, detoxification of xenobiotics, and exploitation avoid substrates. Although fungal CYP-dependent biotransformation for the selective oxidation avoid organic compounds in yeast system is advantageous, it often suffers from a shortage avoid intracellular NADPH. In this study, we aimed to investigate the use of bacterial glucose dehydrogenase (GDH) for the intracellular electron regeneration of fungal CYP monooxygenase in a yeast reconstituted system. The benzoate hydroxylase FoCYP53A19 and its homologous redox partner FoCPR from Fusarium oxysporum were co-expressed with the BsGDH from Bacillus subtilis in Saccharomyces cerevisiae for heterologous expression and biotransformations. We attempted to optimize several bottlenecks concerning the efficiency of fungal CYP-mediated whole-cell-biotransformation to enhance the conversion. The catalytic performance of the intracellular NADPH regeneration system facilitated the hydroxylation of benzoic acid to 4-hydroxybenzoic acid with high conversion in the resting-cell reaction. The FoCYP53A19+FoCPR+BsGDH reconstituted system produced 0.47 mM 4-hydroxybenzoic acid (94% conversion) in the resting-cell biotransformations performed in 50 mM phosphate buffer (pH 6.0) containing 0.5 mM benzoic acid and 0.25% glucose for 24 h at $30^{\circ}C$. The "coupled-enzyme" system can certainly improve the overall performance of NADPH-dependent whole-cell biotransformations in a yeast system.

• Transactions of the Korean hydrogen and new energy society
• /
• v.33 no.6
• /
• pp.723-732
• /
• 2022

Cracking ammonia inside solid oxide fuel cell (SOFC) stack is a compact and simple way. To prevent sharp temperature fluctuation and increase cell efficiency, the decomposition reaction should be spread on whole cell area. This leading to a question that, how does anode thickness affect the conversion rate of ammonia and the cell voltage? Since the 0D model of SOFC is useful for system level simulation, how accurate is it to use equilibrium solver for internal ammonia cracking reaction? The 1D model of ammonia fed SOFC was used to simulate the diffusion and reaction of ammonia inside the anode electrode, then the partial pressure of hydrogen and steam at triple phase boundary was used for cell voltage calculation. The result shows that, the ammonia conversion rate increases and reaches saturated value as anode thickness increase, and the saturated thickness is bigger for lower operating temperature. The similar cell voltage between 1D and 0D models can be reached with NH₃ conversion rate above 90%. The 0D model and 1D model of SOFC showed similar conversion rate at temperature over 750℃.

• Journal of Energy Engineering
• /
• v.25 no.3
• /
• pp.66-72
• /
• 2016

In this study, a sulfonated poly(arylene ether ketone) block copolymer was prepared from hydrophilic oligomer and hydrophobic oligomer. The structure of the prepared membrane was characterized by $^1H$-NMR, FT-IR and GPC. The $M_w$(weight-average molecular weights) of the polymer was $209,700g\;mol^{-1}$ and the molecular weight distribution($M_w/M_n$) of 1.25 was obtained. The prepared membrane showed excellent thermal stability with gradual weight loss up to $200^{\circ}C$. The proton conductivity of SPAEK block copolymer reached the maximum of $9.0mS\;cm^{-1}$ at $90^{\circ}C$ under 100% relative humidity (RH). From the observed results, it is necessary to do more aggressive attempt to study the possibility of application as an ion-conductive composite electrolyte.

• YAKHAK HOEJI
• /
• v.21 no.3
• /
• pp.167-171
• /
• 1977

A new assay method for delta-l-dehydrogenated-3-ketoco-rticosteroid in the presence of proteinous material or whole-cell-enzyme and 3-ketocorticosteroid has been developed. This method makes use of the linear relationship between the ratio of absorbances at 265 nm and at 242 nm and the fractional concentration of delta-1-3-ketosteroid. Theoretical values were calculated based on the absorbances of proteinous material at fixed concentrations of the 3-ketosteroid and delta-1-dehydrogenated-3-ketosteroid. The values obtained experimentally showed good agreement with the values obtained experimentally showed good agreement with the values theoretically predicted. The new assay method developed for the steroid mixtiure containing proteinous material is of some practical importance. The use of such assay method enables one to determine the enzyme activity and the rate of enzyme reaction or conversion rather quickly, easily and accurately. By the use of this assay method, the reaction kinetics of whole-cell-enzyme has also been studied. It was found that it followed the simple Michaelis-Menten type enzyme kinetics. Also the reversibility of this reaction with actively metabolizing cell was examined. It was found that delta-l-dehydrogenated-3-ketosteroid could not be hydrogenated reversibly to 3-ketosteroid by this enzyme system.

• KSBB Journal
• /
• v.26 no.6
• /
• pp.569-571
• /
• 2011

Reduction of 3-chloro-4-fluoropropiophenone by Saccharomyces cerevisiae as a whole cell biocatalyst was optimized. Effects of glucose, S. cerevisiae and 3-chloro-4-fluoropropiophenone concentrations on conversion of reduction reaction was investigated. Optimum concentrations of glucose, S. cerevisiae and 3-chloro-4-fluoropropiophenone were 100, 40 and 20 g/L, respectively. At optimum condition, 100% of conversion was achieved in 12 hours of reaction.