| 초록 |
Hyperthermophiles isolated in the last decade have attracted many interests due to theirpotential use as an important resource for biotechnologically useful products. However,cultivation of the hyperthermophiles with controlled bioreactors are rare and culture techniquesat high temperatures are still lacking. One of the problems encountered in the cultivation of thermophiles is evaporation of theliquid medium. Rapid decrease of the culture volume during fermentation often adverselyaffects the cell growth due to increased concentration of nutrients and/or inhibitory productsin the medium. Fed-batch culture techniques, on the other hand, have been widely adopted for highdensity cultivation of various microorganisms. In a conventional fed-batch system, culturevolume varies with time and this transient condition makes it difficult to analyze the growthkinetics in a fed-batch culture system. In some fed-batch operations, very concentrated feedsolution or powder form of nutrient was supplied to the culture to reduce the volumeincrease. In this work we have proposed a new fed-batch strategy, called a constant-volumefed-batch (CVFB) system, for hyperthermophile cultivation. In this system, culture volumewas maintained at a constant level by compensating the loss of culture volume with feedmedium and water. This method not only eliminates the difficulties caused by evaporation ofthe medium but also resolves the volume-change problem. To explore the applicability of theproposed scheme, we have investigated high density cultivation of Sulfolobus solfataricus, ahyperthermophilic aerobe which normally grows at 75 to 85 oC. We also analyzed cell culturekinetics in the CVFB system.
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