Cultivation of marine microalga Isochrysis galbana Parke and the production of eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA) were studied in flask, bottle, and bubble column reactors. The medium prepared from natural sea-water gave a higher final cell density than the medium prepared from...
Cultivation of marine microalga Isochrysis galbana Parke and the production of eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA) were studied in flask, bottle, and bubble column reactors. The medium prepared from natural sea-water gave a higher final cell density than the medium prepared from synthetic sea-water. Nitrate was a better nitrogen source than ammonium. In the range of 0.4-2mM, the final cell density was proportional to the initial nitrate concentration and the cell yield was estimated to be 8.5g dry cell wt/g N. For phosphate, optimal growth was observed in 0.1-l.0mM in spite of a considerable variation in medium pH. The addition of Tris buffer at 5mM or 7mM could stabilize the medium pH, but significantly reduced both growth rate and final cell density. The effect of trace elements and vitamins was negligible. Optimal temperature and initial pH were 20℃ and 8. When the intensity of incident light was varied in the range of 400-2100 lux, the growth rate increased up to 1850 lux and remained constant thereafter. With increasing working volume from 10ml to 70 ml, the final cell density decreased although the initial growth rate did not change. Optimal agitation speed was 100rpm when working volume was 30ml. In flask culture under optimal conditions, the maximal specific growth rate was 0.021hr^(-1) and the final cell density was 1.07mg cell/ml. Optimal CO_(2) concentration and gas flow rate in bottle and bubble column culture were 1% and 0.75vvm, respectively. The production of EPA and DHA was studied in batch culture, under constant conditions and under varied conditions. In the latter case, to test the induction conditions for EPA and DHA the alga grown under optimal growth conditions for 4 or 7 days was challenged by various environmental or nutritional conditions. Important parameters tested were N-source (kind and concentration), vitamins, trace elements, temperature, and light intensity. Intracellular content of total fatty acid, EPA and DHA, concentration of EPA, DHA, and biomass were monitored. Although there were some variations, high nitrate, low temperature and reduced light intensity resulted in high intracellular content of EPA and DHA. In the induction experiments, EPA and DHA(mg/g biomass) increased after switching N-source from nitrate to ammonium and lowering the concentration of vitamins and trace elements. Also, the biosynthesis of EPA and DHA was stimulated when light intensity and temperature were low and dark phase incubation or dark/light cycle were executed. When the culture conditions were varied during the production period, high intracellular content of EPA and DHA at 15.9mg/g biomass and 12.1mg/g biomass were obtained, which are about 1.5-fold higher than those obtained from simple batch cultivation.
Cultivation of marine microalga Isochrysis galbana Parke and the production of eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA) were studied in flask, bottle, and bubble column reactors. The medium prepared from natural sea-water gave a higher final cell density than the medium prepared from synthetic sea-water. Nitrate was a better nitrogen source than ammonium. In the range of 0.4-2mM, the final cell density was proportional to the initial nitrate concentration and the cell yield was estimated to be 8.5g dry cell wt/g N. For phosphate, optimal growth was observed in 0.1-l.0mM in spite of a considerable variation in medium pH. The addition of Tris buffer at 5mM or 7mM could stabilize the medium pH, but significantly reduced both growth rate and final cell density. The effect of trace elements and vitamins was negligible. Optimal temperature and initial pH were 20℃ and 8. When the intensity of incident light was varied in the range of 400-2100 lux, the growth rate increased up to 1850 lux and remained constant thereafter. With increasing working volume from 10ml to 70 ml, the final cell density decreased although the initial growth rate did not change. Optimal agitation speed was 100rpm when working volume was 30ml. In flask culture under optimal conditions, the maximal specific growth rate was 0.021hr^(-1) and the final cell density was 1.07mg cell/ml. Optimal CO_(2) concentration and gas flow rate in bottle and bubble column culture were 1% and 0.75vvm, respectively. The production of EPA and DHA was studied in batch culture, under constant conditions and under varied conditions. In the latter case, to test the induction conditions for EPA and DHA the alga grown under optimal growth conditions for 4 or 7 days was challenged by various environmental or nutritional conditions. Important parameters tested were N-source (kind and concentration), vitamins, trace elements, temperature, and light intensity. Intracellular content of total fatty acid, EPA and DHA, concentration of EPA, DHA, and biomass were monitored. Although there were some variations, high nitrate, low temperature and reduced light intensity resulted in high intracellular content of EPA and DHA. In the induction experiments, EPA and DHA(mg/g biomass) increased after switching N-source from nitrate to ammonium and lowering the concentration of vitamins and trace elements. Also, the biosynthesis of EPA and DHA was stimulated when light intensity and temperature were low and dark phase incubation or dark/light cycle were executed. When the culture conditions were varied during the production period, high intracellular content of EPA and DHA at 15.9mg/g biomass and 12.1mg/g biomass were obtained, which are about 1.5-fold higher than those obtained from simple batch cultivation.
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#Isochrysis galbana Parke 해양미세조류 EPA DNA
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