• KSBB Journal
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• v.20 no.4
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• pp.271-277
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• 2005

The polyunsaturated fatty acids (PUFAs) are mostly synthesized by the marine original microorganisms. In this study, the effect of concentrations of glucose, NaCl, and $MgSO_4{\cdot}7H_2O$ on both the growth and the production of lipid and Docosahexaenoic acid (DHA) was investigated using Thraustochytrium aureum ATCC 34304. $Y_{Lipid/X}\;and\;Y_{DHA/Lipid}$ increased according to the increase of initial glucose concentration until 15 g/L of glucose. The maximum values of $Y_{Lipid/X}\;and\;Y_{DHA/Lipid}$ were 0.18 g/g and 0.41 g/g respectively at 15 g/L of glucose. The biomass yield, $Y_{x/s}$, however, was constant as 0.378 g/g regardless of initial glucose concentrations in the range of 5 g/L to 25 g/L. The specific growth rate of T. aureum increased also with initial glucose concentration from 5 g/L and 15 g/L. The maximum value was $0.79\;day^{-1}$ at 15 g/L of glucose, and the growth rate decreased to $0.57\;day^{-1}$ and remained constant according to initial sugar concentration in the range of higher than 15 g/L of glucose. The concentration of NaCl was changed from 0 g/L to 48 g/L, in order to study the characteristics of the growth and the production of lipid and DHA according to NaCl concentration. The growth and the production of lipid as well as DHA stopped all at 0 g/L of NaCl and the maximum values of all the three variables occurred at 24 g/L. The effect of $MgSO_4{\cdot}7H_2O$ concentration was also investigated not to find the growth and the production of lipid and DHA at 0 g/L. However, the growth and the Production with $MgSO_4{\cdot}7H_2O$ concentration increased to reach the maximum values at 18 g/L of $MgSO_4{\cdot}7H_2O$.

• Korean Journal of Food Science and Technology
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• v.18 no.3
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• pp.210-214
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• 1986

The culture conditions and cell composition of a hydrogen bacterica, Alcaligenes eutrophus ATCC 17697. were investigated. Optimum pH and temperature for cell growth under autotrophic condition ($H_2$ as energy source, $CO_2$, as crabon source) were around 7.0 and $30^{\circ}C$, respectively. Effect of oxygen partial pressure in the range of 0.059 atm and 0.27 atm on cell growth was also studied. Maximum specific growth rate $({\mu}max=0.31hr^{-1})$ was observed at 0.11 atm of oxygen partial pressure $(H_2:O_2:CO_2=7:1:1)$. The contents of crude protein, nucleic acid and ash in cells were 69.2%, 17.6%, and 3.62%, respectively.

• KSBB Journal
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• v.13 no.1
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• pp.101-107
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• 1998

Carbon dioxide is estimated to be responsible for 60% of the global warming effect, and this percentage is tending upward. Studies on removal and fixation of $CO_2$ in the flue gas are recognized as one of the important roles of the future biotechnology. Photobiological systems have considerably higher photosynthetic efficiency than conventional biomass system. The experiment for the photosynthetic fixation of $CO_2$ and the biomass production was performed with various initial cell concentration in a tubular photobioreactor and a bubble column $CO_2$ contactor with a gas sparger of $CO_2$ -enriched air(0.03~20%). Synechocystis PCC 6803 could grow at 10~20% $CO_2$ content under pH control. The highest specific growth rate, 0.0258 $h^{-1}$ , was obtained at 5% $CO_2$-air mixture. The maximum cell production rate, 0.2784 g/L.day, was obtained when the initial cell concentration was 0.45 g/L at 5% $CO_2$ -air mixture. The maximum cell concentration was 2.03 g/L in the tubular photobioreactor when the light intensity was $45.5{\mu}$ $E/m^2$ . s. This system showed 0.482 g $CO_2$ /L . day of the $CO_2$ fixation.

• KSBB Journal
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• v.10 no.2
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• pp.196-203
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• 1995

The effects of majors nutrients and environmental factors on polyoxins biosysnthesis were examined for the overprodution of antifungal agent polyoxins using Streptomyces sp. 809-11. The cell mass at the exponential growth phase was increased when soluble starch was used, while the polyoxins biosynthesis was increased with the formation of filamentous mycelium when glucose was used as a carbon source. It was, therefore, recommendable to use both soluble starch and glucose simultaneously as carbon sources for the cell growth and polyoxins production. The high concentration of ammonium sulfate (151.4 mM) resulied in the improvement of polyoxins production. The optimal concentration of $K_2HPO_4$for polyoxins production was found to be 0.5mM. By applying fed-batch culture, polyoxins production was improved to about 2-folds compared to the result from the batch culture.

• KSBB Journal
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• v.20 no.6
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• pp.413-417
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• 2005

The purple sulfur phototrophic bacterium, Thiocapsa roseopersicina NCIB 8347 has been studied on hydrogen production and cell growth under different culture conditions, such as light source, light intensity, and growth temperature. T. roseopersicina showed maximum cell growth of 1.38 and 1.42 g-DCW/L under 7.5-10 klux of halogen and fluorescent light, respectively, and produced maximum amount of hydrogen with values of 0.90 and 0.48 $mL-H_2/mg$-DCW under the irradiation of 10 klux of halogen and fluorescent light, respectively. The optimum growth temperature for hydrogen production was $26^{\circ}C$, and hydrogen production rate was lowered over $30^{\circ}C$. When T. roseopersicina was grown photoheterotrophically under irradiation of 8-9 klux of halogen lamp, the generation time was 4.2 hr. The strains started producing hydrgen from the middle of the logarithmic growth phase and continued until succinate concentration leveled out.

• Korean Journal of Food Science and Technology
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• v.15 no.2
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• pp.202-204
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• 1983

A strategy for the automation of glutamic acid fermentation has been developed by the use of $CO_2$ analyzer together with a controller. It was found that a linear relationship existed between growth and $CO_2$ level in the exit gas. Therefore penicillin addition at an appropriate biomass concentration to excrete glutamate could be achieved automatically. In addition, an automatic batch feeding method (fed-batch culture) provided a means of overcoming substrate inhibition effects on growth and glutamic acid production in batch culture, thereby increasing productivity and product yield.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.101-106
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• 1985

The effects of ethanol on the specific rates of growth and ethanol production were found to be threshold and linear inhibition. The degree of inhibition was more apparent on the specific growth rate while ethanol production was continued even the growth was ceased. The nature of uncoupling between the growth (anabolism) and ethanol production (catabolism) was clearly observed under high concentration of ethanol. The uncoupling indicated that ethanol concentration plays a great role in maintenance energy coefficient.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1151-1156
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• 1996

Effects of xylose and glucose on the xylitol production were investigated with Candida parapsilosis KFCC 10875. With increasing the ratio of glucose to xylose, xylitol production decreased but ethanol and glycerol production increased. The maximum concentrations of ethanol and glycerol were 21.5 g/l and 3.6 g/l, respectively, in a medium consisting of 10 g/l xylose and 40 g/l glucose. No xylitol was formed in the glucose medium without xylose since xylitol could not be produced from glucose alone. The inhibitory effect of ethanol, a major by-product, on xylitol production was also studied. As the added ethanol concentration was increased, xylitol production decreased. When cells were inoculated in a xylose medium after removing the by-product (ethanol), xylitol production was not inhibited. The concentrated cells grown on xylose or glucose were inoculated in a fermentor containing the xylose medium. The total activities $(specific{\;}activities{\times}\;cell\;concentration)$ of xylose reductase and xylitol dehydrogenase in concentrated cells grown on glucose were the same as those in a normal fermentation; the specific activities of the above enzymes in the cells grown on xylose were the same as those in a normal fermentation. It indicates that the xylitol productivity of concentrated cells grown on xylose could be increased with increasing the cell concentration. By using concentrated cells of 20 g/l grown on xylose, the final xylitol concentration of 40 g/l was obtained for 18 h fermentation from 50 g/l xylose.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.324-331
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• 2009

MK1 strain, an obligate aerobic heterotrophic bacterium isolated from the rotten tissue of Neungee mushroom (Sarcodon aspratus), produces a copious amount of exopolysaccharide (EPS), which could evoke macrophage activation. Investigations on optimal culture conditions of MK1 and physical properties of MK1 EPS were made. Glucose, galactose, fructose, and sucrose supported well growth of MK1, but potato starch and dextrin did not. However, lactose seemed to be a less favorable carbon source. Optimal growth of MK1 was obtained at pH 7.0, $30^{\circ}C$, and 200 rpm with 2% glucose, and 0.2~0.05% $(NH_4)_2SO_4$. $EPS_{opt}$ obtained from an optimal growth condition constituted of carbon (37.1%), nitrogen (2.2%), oxygen (49.3%), and hydrogen (6.4%), but no sulfur. Paper chrogromatogram of the acid-hydrolysate of $EPS_{opt}$ suggested that MK1 EPS seemed to be hetropolysaccharide composed of a few number of monosaccharides including amino- and acidic-sugars. Its molecular mass determined by SDS-polyacrylamide gel electrophoresis varied from 14.8 to 47.9 kDa. Physical properties of $EPS_{glu}$ obtained from cell grown in glucose medium, such as relative viscosity ($_{rel}$) and crystalline morphology were rather affected by pH of the growth medium. Relative viscosity ($_{rel}$) of exopolysaccaride (0.1 g/ml) harvested from cells grown at medium pH ranging from 6.0 and 7.5 was 1.23 and 1.39, respectively. The freeze-dried exopolysaccharide obtained at low pH (6.0 and 6.5) was fine crystaloid and water-soluble, whereas those obtained at high pH (7.0 and 7.5) was rather gluey and less water-soluble.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.172-176
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• 2006

In order to increase the productivity of lipstatin by Steptomyces toxytricini, the effect of medium components on the lipstatin production was investigated. Using TSB medium as a basal medium, a variety of carbon sources, nitrogen sources, lipid and fatty acids was supplemented into a fermentation medium. The seed culture of S. toxytricini grown in 25 ml TSB medium at $28^{\circ}C$ for 3 days with agitation at 200 rpm was inoculated in the size of 2% in fermentation media containing different components and fermented at $28^{\circ}C$ for 60 more hrs. In the examination of the effect of carbon sources, the best cell growth was observed in fermentation media supplemented with glucose or glycerol, but the lipstatin productivity was the highest in media containing lactose or sucrose. Among complex nitrogen sources, yeast extract was the best one for cell growth, but the highest lipstatin production was found in TSB media composed of 1.7% casitone and 0.3% soytone. The increased concentration of triolein as a lipid caused the promotion of cell growth but the significant suppression of lipstatin production. When 0.5% fatty acids were supplemented to fermentation medium, unsaturated fatty acids like linoleic or oleic acid suppressed cell growth as well as lipstatin production, but 2 times higher lipstatin production was achieved by stearic acid, a saturated fatty acid, differently from expectation.