1994 年 1994 巻 251 号 p. 276-282
Porous hydroxyapatite (HAp) particles were prepared by sintering HAp powder mixed with carbon powder at 1150°C for 2hr. The HAp powder was synthesized by the method of precipitation from calcium nitrate and diammonium hydrogen phosphate. Ethanol fermentation using the sintered HAp as a carrier was investigated, and compared with that using a commercial carrier, porous glass. First, yeast cells were immobilized on the sintered HAp by the cultivation in a medium at 30°C, and the immobilized yeast reached a maximum 2.2×108 cells per g-carrier with a particle diameter of 2380-3360pm. Secondly, a batch ethanol fermentation with the immobilized yeast on the sintered HAp at 30°C was found to proceed more smoothly than that with immobilized yeast on the porous glass in the medium containing glucose concentration of 10% (w/v). In the medium composed of glucose more than 20% (w/v), although the fermentation with the sintered HAp had the same tendency as the above up to ethanol concentration of about 6% (w/v), the fermentation was inhibited thereafter by the calucium cation eluted from the sintered HAp. In a continuous fermentation with immobilized yeast on the sintered HAp, ethanol concentration of 7.1% (w/v) was stably produced by adjusting the pH of the medium in the reactor to 5.0 at 24hr intervals under the conditions of glucose concentration of 15% (w/v) in the medium and the residence time of 5.8hr.