초록
The purpose of this study was to develop a vertical mass-flow type bioreactor (VMFB) consisting of both aerobic and anaerobic zones to produce ethanol by Simultaneous Saccharification and Fermentation (SSF). Potato starch and microorganisms of Aspergillus awamori, Rhizopus japonicus, and Zymomonas mobilis were used. The highest ethanol concentration with 6.0 % (w/v) initial starch were 2.99g/L by traditional two-stage Separate Hydrolysis and Fermentation (SHF, co-suspension culture, flask, 48 h), 17.71g/L (SHF, co-immobilization culture, flask, 84h), and 21.68g/L (SSF, co-cultured in VMFB, 27 h), respectively. In the repeated-batch process (3 cycles) using the VMFB, stable ethanol production was 95.97g/L after 72h. Increase of the starch concentration from 6.0% to 12.0% (w/v) resulted in higher ethanol production of 60.18g/L after 51h. Another type of starch was tested, and 27.91g/L of ethanol was obtained from 6.0% (w/v) cassava starch. The results showed that the performance of VMFB cannot only enhance the ethanol yield, but also has great benefit for high fermentation efficiency and less cost.