• Journal of Microbiology and Biotechnology
• /
• v.9 no.6
• /
• pp.751-756
• /
• 1999

For mass production of poly(3-hydroxybutyrate) (PHB), high cell density cultures of Ralstonia eutropha were carried out in 2.5-1 and 60-1 fermentors by two fed-batch culture techniques of nitrogen and phosphate limitation. When the nitrogen limitation technique was employed using both an on-line glucose monitoring and control system, a high concentration level of PHB (121g/l) was obtained in the small-scale fermentor of 2.5 1. However, the PHB concentration obtained in a large-scale fermentor of 60 1 only turned out to be 60g/l. In contrast, when another fed-batch culture technique of the phosphate-limitation employing dissolved oxygen (DO) stat glucose feeding was used, a large amount of PHB was successfully produced in both 60-1 and 2.5-1 fermentors. In a 2.5-1 fermentor, concentrations of PHB and cells obtained in 58 h were 175 and 210 g/l, respectively, which corresponded to the PHB productivity level of 3.02 g/l/h. In a 60-1 fermentor, a final cell concentration of 221 g/l and a PHB concentration of 180 g/l with PHB productivity level of 3.75 g/l/h were obtained in 48h. PHB content and yield from glucose were 81% and 0.38g PHB/g glucose, respectively. These data suggest that the phosphate limitation technique is more effective compared to nitrogen limitation in the mass production of PHB by R. eutropha of a large scale.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.1
• /
• pp.68-73
• /
• 2004

Ferritin is an iron storage protein found in most living organisms. For expression and industrial use, human light chain ferritin (L-ferritin) was cloned from human liver cDNA library and expressed in Pichia pastoris strain GS115. The recombinant L-ferritin in Pichia pastoris was glycosylated. In a fed-batch culture, the cell mass reached about 57 g/l of dry cell weight, and the L-ferritin in the cell was increased to about 95 mg/l after 150 h. In an atomic absorption spectrometry analysis, the intracellular content of iron in the L-ferritin transformant was measured as $1,694{\pm}85\;\mu\textrm{g}g/g$, which is 5.4-fold more than that of the control strain. This L-ferritin transformant could serve as iron-fortified nutrients in animal feed stock.

• Journal of Nutrition and Health
• /
• v.38 no.8
• /
• pp.626-636
• /
• 2005

This study was undertaken to examine effects of dietary intake of garcinia cambogia extract, soy peptide and L-carnitine mixture on body weight gain and obesity-related bio-markers in rats fed high-fat diet for 9 weeks with or without regular treadmill exercise. Forty 5-week-old male Sprague-Dawley rats were randomly divided into four groups; sedentary control group (SC), exercised control group (EC), sedentary formula-fed group (SF), and exercised formula-fed group (EF). The SC and EC rats were fed high-fat control diet (fat comprises$40\%$ of total caloris), and SF and EF rats were fed high-fat formula (composed of garcinia cambogia, soy peptide and L-carnitine) supplemented diet. Statistical analyses by two-way ANOVA indicated that the regular treadmill exercise significantly lowered cumulative body weight gain, total visceral fat mass, and epididymal, perirenal and retroperitoneal fat pad weights, and serum concentrations of total cholesterol and LDL + VLDL cholesterol, insulin, c-peptide and leptin. Feeding the formula also resulted in significant reductions in cumulative body weight gain and visceral fat pad weights, along with other related parameters including serum total and LDL + VLDL cholesterol levels, and hepatic enzyme activities involved in fatty acid synthesis. Statistical analyses by one-way ANOVA revealed that the formula consumption significantly improved body weight gain ($18\%$ reduction), total visceral fat weight ($20\%$ reductions), and serum total ($43\%$ reduction) and LDL + VLDL cholesterol ($54\%$ reduction) levels, as well as serum levels of insulin ($49\%$ reduction), and c-peptide ($41\%$ reduction) in sedentary rats, but failed to exhibit significant reductions in these indices in animals under treadmill exercise program. Taken together, these results suggest that the treadmill exercise per n exhibited significant improvements in body fat reduction and other related bio-markers, and so the formula consumption did not achieve a further significant reductions in these bio-markers in exercised rats. Nevertheless, animals fed the formula with regular exercise showed the most efficient weight reduction compared to other groups either fed formula without exercise or received regular exercise without dietary supplementation.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.5
• /
• pp.643-650
• /
• 1996

A long term feeding trial was conducted to study the effects of different dietary vitamin C levels on growth and its tissue distributions in juvenile Korean rockfish, Sebastes schlegeli. Prior to the start of feeding trial, fish were fed the basal diet supplementing no L-ascorbic acid for four weeks to minimize their body reserves of vitamin C. Then fish were divided into six groups with triplicates and given one of the laboratory semipurified diets supplementing either 0, 25, 50, 75, 150, or 1500 mg L-ascovbic acid (AA)/kg diet $(C_0,\;C_{25},\;C_{50},\;C_{75},\;C_{150},\;&\;C_{1500})$. Fish fed the $C_0$ diet had lower percent weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio than did fish fed the other diets (P<0.05). After 28 weeks of feeding trial, tissue AA concentrations of fish fed $C_0$ diet were lower than those of fish fed $C_{1500}$ diet (P<0.05). A large amount of total tissue Ah may be reserved in muscle, but the unit AA concentration seemed to be higher in brain than did the other tissues. The growth performances of fish fed $C_{25}$ diet were not different compared to those of fish fed $C_{50}-C_{1500}$ diets (P>0.05), and diet analysis of vitamin C showed that the $C_{25}$ diet had 65 mg AA/kg diet. Therefore, the present long-term study may suggest that the dietary vitamin C requirement is approximately 65 mg AA/kg diet in juvenile Korean rockfish.

• KSBB Journal
• /
• v.18 no.4
• /
• pp.249-254
• /
• 2003

Experiments were carried out to select an industrial nitrogen source and optimize erythritol production by Candida magnoliae in fed-batch culture. Among the industrial nitrogen sources tested, light steep water (LSW) was found to be the best nitrogen source for producing erythritol, based on erythritol yield and raw material price. The maximum erythritol concentration obtained a 131.6 g/L, with a 52.6％ yield and 0.52 g/L-hr productivity from a 250 g/L glucose and 43.3 mL/L LSW in batch culture. Two-stage fed-batch culture was chosen to improve the volumetric productivity and the yield of erythritol. High cell density culture in cell growth stage was achieved by batch type culture containing 100 g/L glucose and 500 mL/L LSW. The cell concentration was 71.0 g/L after 23 hours of culture. Erythritol productivity was decreased by increasing glucose concentration in the production stage. But 37.3％ of the maximum erythritol yield was obtained with 185.5 g/L of erythritol and 1.66 g/L-hr of productivity when 820 g of glucose powder was directly added to a concentration of 450 g/L glucose in production stage.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.8 no.5
• /
• pp.303-305
• /
• 2003

Scale-up of hirudin production from Saccharomyces cerevisiae from bench-scale to pilot-scale was carried out based on constant volumetric oxygen transfer coefficient (K$\sub$L/a). Fed-batch mode of cultivation using step-wise feeding strategy of galactose was employed for the production of hirudin in a 30-L and a 300-L pilot-scale fermentor. The final hirudin concentrations were achieved 390 mg/L and 286.1 mg/L, and the volumetric productivities were 80.4% and 90.7% with the 30-L and 300-L fermentors, respectively, compared to the productivity of the 5-L bench-scale fermentor.

• Journal of the East Asian Society of Dietary Life
• /
• v.14 no.3
• /
• pp.243-250
• /
• 2004

The effect of hemicellulose extracted from Shiitake mushroom(Lentinus edodes) on the level of blood sugar and cholesterol in the diabetes-induced rat by streptozotocin(STZ) was investigated. The yield of hemicellulose by extraction process of 5% salt extraction, preparation of alcohol insoluble substance, IN KOH extraction, acid precipitation(pH 3.0), and dialysis was 9.24%. The experimental plots divided to 1% cellulose group(control), 0.5% hemicellulose group(H-l) and 1% hemicellulose group(H-2). The groups were fed for 6 weeks, then continuously fed for 1 week after induction of diabetes by STZ. Feed intakes, weight gain and feed efficiency of the each groups were not significantly different, while water intakes and liver weight of H-2 group were lower than those of control and H-l group. Weight of liver in the H-2 group was significantly lower than those of control and H-l groups. The amounts of feces were 0.32 g/day in the control group, 0.43∼0.44 g/day in the H-l and H-2 groups, while the amounts of urine were 15.28 mL/day in the control group, 10.83∼11.20 mL/day in the H-l and H-2 groups. The content of blood glucose before diabetes induction(fed for 3∼5 weeks) was 111.2-132.6 mg/dL in the control group, not significantly different from others; After diabetes induction, however, the contents were 212.8 mg/dL in the control group, 140.0-144.0 mg/dL in the H-l and H-2 groups, which showed significant difference. Urine glucose contents of H-2 group before and after diabetes induction were lower than those of control and H-l groups. There was no significant difference in the content of neutral lipid between each groups. Total cholesterol contents were 101.6 mg/dL in the control group, 56.∼64.0 mg/dL in the hemicellulose groups. HDL-cholesterol content and atherogenic index of hemicellulose groups were lower than those of control group, respectively. In conclusion, the hemicellulose extracted from Shiitake mushroom represented improving and preventing effects for diabetes.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.271-274
• /
• 2000

A study was carried out to select a nitrogen source and the optimize the C/N ratio for the maximum cell growth of Phaffia rhodozyma in fed-batch culture. The yeast extract was the best organic nitrogen source. In the batch culture experiments, the highest cell yield was obtained 0.575 g-cell/g-glucose from 10 g/L and 10 g/L yeast extract. In the fed-batch experiments, the maximum cell concentration was obtained 33.1 g/L from the C/N ratio of 2:1 while the astaxanthin concentration of cell was Increased by increasing the C/N ratio, of feed medium.

• Journal of Power Electronics
• /
• v.18 no.4
• /
• pp.955-964
• /
• 2018

In this paper, an active capacitor-diode-switch (CDS) snubber is proposed for L-type current-fed isolated DC-DC converters. The proposed CDS-clamped converter has a number of advantages. It can achieve wide range zero-voltage switching (ZVS) on two switches, a continuous input current with a low ripple, a reduction of one active switch and high efficiency. The operating principles, analysis and parameter design guideline are presented. A 300 W prototype is built to test the proposed converter. Simulation and experimental results are shown at 30 V input voltage and 400 V output voltage.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.6
• /
• pp.814-819
• /
• 2015

The natural crosslinking agent genipin has been applied widely in biomedicines and foods nowadays. Because of the special hemiacetal ring structure in its molecule, it can only be prepared by hydrolysis of geniposide according to biocatalysis. In this research, strategies including aqueous-organic biphasic catalysis and substrate fed-batch mode were adopted to improve the biocatalysis process of genipin. A 10 L ethyl acetate-aqueous biphasic system with geniposide fed-batch led to a satisfying genipin yield. With Fusarium solani ACCC 36223, 15.7 g/l genipin in the ethyl acetate phase was obtained, corresponding to space-time yields of 0.654 g l^-1 h^-1.