• KSBB Journal
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• v.14 no.2
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• pp.160-166
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• 1999

High cell density cultivation of microalga Dunaliella bardawil using nitrogen fed-batch cultures was studied in batch flask. Optimum environmental conditions include concentrated nutrients except NaCl and carbon sources, carbon sources, pH, light, agitation, nitrate and phosphate ions. Cell growth, consumption rates of nitrate and phosphate ions were monitored. Optimal conditions for higher cell density were found to be(in the range tested): 5 times concentrated media(1 times-10 times concentrated media) pH 8.0 (7.0-9.0) white light(blue and red light) 15mM of nitrate (0.94-15mM) 250mM $NaHCO_3$ and $CO_2$ gas. However, the addition of phosphate ions did not enhance the algal maximum cell density and specific growth rate. Nitrate was found to be effective for the cell growth. The maximum cell density of fed-batch culture using nitrate ions in $8.955{\times}106$cells/ml after 189hr incubation.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.845-848
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• 2001

For understanding physiology and metabolism under various culture conditions, combined analysis of transcriptome and proteome is attractable way. We have manufactured DNA microarray containing 2,850 genes including all functionally known and putative ones. In this study, we report analysis of transcriptome and proteome during the high cell density culture of E. coli by using DNA microarray and 2-DE. Fed-batch fermentation of E. coli was carried out by exponential feeding of nutrients until the maximum cell density reached 74 g dry cell weight/L (g DCW/L). Changes in transcriptome and proteome during the HCDC are analyzed qualitatively and quantitatively to provide their physiological and metabolic meanings.

• KSBB Journal
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• v.6 no.3
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• pp.231-240
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• 1991

Recently, developments of large scale and high density cell culture methods have been the objects of many researches, because the demand of various pharmaceutical products produced by animal cell culture has been rapidly increasing. The cell culture equipment should have the requirements such as sufficient oxygen transfer and mixing, low shear stress and surface tension, and small foaming. In order to develop a proper bioreactor meeting these requirements simultaneously, a perfluorocarbon having high solubility of oxygen was sprayed into the medium as an oxygen carrier instead of air. Also, a new impeller was developed and combined together with the perfluorocarbon spraying system so as to design a new bioreartor for cell cultivation. The new impeller had better characteristics of mixing and oxygen transfer than the paddle and cell-lift impellers based on the same, shear rate. But, it was observed that the volumetric oxygen transfer coefficient of the new bioreactor decreased with increasing cell density during E. coli fermentation.

• Journal of environmental and Sanitary engineering
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• v.16 no.3
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• pp.22-27
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• 2001

It have been investigated how algal and bacterial symbiotic reaction influences on removal of organic carbon in river ecosystem. And artificial experimentation apparatus was made for algae'and bacteia'culture as lab scale. Investigating and researching minutely the change of concentration of organic carbon substrate and the change of population density of algae'and of bacteria'with this artificial experimentation apparatus, the next results could be obtained. 1. Successful decrease of DOC(dissolved organic carbon) could not be expected unless algal and bacterial biomass floe was nut formed effectively and unless biosorption was not proceeded effectively in the very culture system in which artificial synthetic wastewater was supplied continuously at constant rate. 2. In conditions of culture liquid of 1335 glucnse mg/L(type 1) and of 267 glucose mg:L(type 2), the algal dominant species was always Chlorella vulgaris in both types in which artificial synthetic wastewater were supplied continuously at constant rate and algae population density was around maximum 107 cells/mL. 3. It was around 108 ~ 107 cells/mL that the population density of heterotrophic bacterium. In culture medium systems type 1 and type 2 in which artificial wastewater were supplied continuously at constant rate, the same density appeared initially when using the population density of Escherichia coli w 3110 as indirect indicator. And this density decreased rapidly till the culturing date 35 days were passed away, while this density increased with gentle slope after same date and then the trend of change at type 2 was more severe than one at type 1. 4. When seeing such a change of population density of Escherichia coli w 3110, the growth of heterotrophic bacterium appeared as survival instinct pattern of broader requirement of nutrient at condition of low concentration of organic carbon substrate than condition of high concentration of same substrate.

• The Journal of Natural Sciences
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• v.14 no.2
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• pp.103-114
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• 2004

This study aims at investigating the effect of soil moisture control and truss limited high density culture on the growth, fruit yield and quality of tomato. To minimize of loss yield of tomato, flower cluster in number was limited to two and three truss and planting density was raised. Soil moisture control was started from 40 days after anthesis and irrigation point was set in -30kPa and -50kPa, which were compared with -10kPa For high density culture, the planting number of truss limited high density culture was planted twice as many as control. Soil moisture repression reduced the growth of stem diameter, leaf and plant height. Leaf chlorophyll content was higher in -50kPa and -30kPa than control. No significant differences, however, shows in -10kPa. The occurrence rate of bloom-end rot and cracking was increased by growing of irrigation repression. Pinching three fruit truss was higher than pinching two fruit truss in the occurrence rate of them. Soil moisture repression resulted in the reduction of fruit weight and in special, truss limited high density was distinctly decreased in -50kPa. The number of fruit was not affected by soil moisture control, but 3rd flower cluster was lower than 2nd flower cluster in the number of fruits and 2nd one was lower than 1st one. Under irrigation repression, rate of dry matter tended to grow in -30kPa, -50kPa compared with control and pinching three fruit truss was higher than two truss. Marketable yield dropped to 36.7%m 46.3 in -30kPa, -50kPa on pinching two fruit truss and dropped to 27.3%, 32.3% in 3rd flower cluster compared with control.

• KSBB Journal
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• v.9 no.2
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• pp.230-237
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• 1994

Spin-filters are used as cell separation devices for achieving high cell density and high productivity in animal cell culture. We have proposed a model for the cell growth in a spin-filter perfusion culture and examined the effects on cell growth by several parameters including ammonia inhibition, specific growth rate, specific feeding rate, and cell retention. Results from computer simulation and sensitivity analysis indicate that the cell retention affects the cell growth mostly while there is a significant inhibition on cell growth by the ammonia accumulated during the culture. The specific feeding rate has minimal effects on cell growth, which is consistant with the fact that the cell growth with a step feeding is quite similar to that with a continuous feeding.

• Journal of Aquaculture
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• v.11 no.1
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• pp.91-97
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• 1998

This paper introduces to a simple culture method and growth of axenic (bacteria-free) rotifer Brachionus rotundiformis for seed stock of rotifer mass culture. This rotifer axenic culture method is based on the washing and transferring with sterilized sea water and modified antibiotic mixture AM9 solution. Population growth (final density on day 16) of axenic cultured rotifer were maintained with a high density and stable growth compared with the control of non-axenic culture (general culture style) through the 3 times-rerunning experiments (trial 1, 2 and 3). But the egg carrying rates of amictic females were not different between the axenic-and non-axenic culture condition. Although, rotifer density was higher in axenic culture, the food (Nannochloropsis oculata) was still remained unutilized than that of the non-axenic culture in third trial culture. These results suggest the possible existence of harmful bacteria for the rotifer population growth in the trial 1 and 3 of non-axenic culture compared to the trial 2. This axenic rotifer culture method is valuable for seed stock of the stable rotifer mass cultures.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.51-53
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• 1996

Fed-batch culture of Pseudomonas oleovorans was carried out for the production of medium-chain-length polyhydroxyalkanoates (MCL-PHAs) using octanoate as a carbon source. Octanoate and the salt solution containing ammounium sulfate and magnesium sulfate were intermittently fed in the course of fermentation. Cell mass and PHA concentrations of 42.8 and 16.8g/L, respectively, could be obtained in 40 h. The PHA content and the PHA productivity were 39.2% and 0.42 g PHA/L-h, respectively. The yields of cell mass and PHA were 0.71 g dry cell mass/g octanoate and 0.28g PHA/g octanoate, respectively. Therefore, octanoate can be used for the production of MCL-PHAs to a high concentration with high productivity.

• Journal of Aquaculture
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• v.13 no.4
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• pp.339-351
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• 2000

Optimal environmental conditions, that sustained fastest growth, lowest mortality and abnormality of the scallop Patinopecten yessoensis, were identified from field experiments undertaken at Chumunjin during 1991-1998. Temperature within the water column 10~30 m depth ranged between 5 and 23$^{\circ}C$; high temperature and daily fluctuation resulted in growth retardation and heavy mortality of the scallop. Optimal salinity range was between 31.5 and 34.5%0 and water transparency 6.0 and 18.1 m, which was significantly affected by phytoplankton density. Chlorophyll concentration ranged between 0.04 and 3.51 f.lgfL. Low temperature and high chlorophyll concentration appear to support faster growth of the scallop. Optimal periods of transplantation for intermediate culture were between mid July and early November: cultured under high density during July-August as a first step and under low density during mid September through early November as a second step. Optimal stocking density in square net cage (<35${\times}$35 em) for intermediate culture was 30-40 individuals per cage for main culture using lantern net and 80 -100 individuals of the size of 1.5 ~ 3.0 em shell height per cage for sowing culture. During the intermediate culture, the highest growth was realized, when the cage was held at water depth between 10 and 15 m. Water depth below 25 m, however, was best to avoid mass mortality during the periods of abnormally high water temperature and high variation of water temperature. The daily growth rate during the intermediate culture was between 0.019~0.381 mm; low in January and February but high in March and April. It is suggested that the main culture is commenced before June under low stocking density to avoid the possibility of mass mortality during summer by high water temperature.

• Journal of Microbiology and Biotechnology
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• v.10 no.4
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• pp.470-475
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• 2000

Genetic chracterstics of the structural gene of guamerin (a novel elastase inhibitor from Korean leech), integrated into the HIS4 locus of chromosomal DNA of Pichia pastoris along with the $\alpha$-factor leader sequence, were investigated. In the selected clone from candidates, two copies of the integration cassette including the structural gene copies of the integration cassette including the structural gene of guamerin were found in the integration site of the chromosomal DNA of P.pastoris. It was demonstrated that the integrated structural gene of guamerin was stable up to about 70 generations in the relay flask culture. Then, a high-cell-density culture could be fulfilled easily by DO-stat fed-batch culture, in which the cell growth and the recombinant guamerin production reached about 250 of OD600nm and 260 mg/l, respectively. Finally, it was revealed that the DNA sequence of the integrated structural gene of guamerin in P. pastoris was maintained correctly in the end of production cells of relay flask culture and high-cell-density culture.