1997 Fiscal Year Final Research Report Summary
UP-GRADE CONTROL METHOD FOR FERMENTATION TO PRODUCE VALUABLE PRODUCTS USING ANAEROBIC MICROORGANISM
| Project/Area Number |
07455330
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生物・生体工学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
ISHIZAKI Ayaaki KYUSHU UNIV., FAC.OF AGR.PROF., 農学部, 教授 (20183163)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Kenji KYUSHU UNIV., FAC.OF AGR.ASSIST.PROF., 農学部, 助手 (20236582)
SONOMOTO Kenji KYUSHU UNIV., FAC.OF AGR.ASSOC.PROF., 農学部, 助教授 (10154717)
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| Project Period (FY) |
1995 – 1997
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| Keywords | pH dependent feed / anaerobic microorganism / ethanol / nisin Z / cell recycling / Zymomonas mobilis / Lactococcus lactis IO-1 / hollow fiber module |
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| Research Abstract |
In continuous ethanol fermentation employing Zymomonas mobilis, computer mediated substrate feed coupled with digital balance to measure weight changes of the culture system was difficult to maintain low remained substrate concentrations. HOWEVER,it was observed that large dilution rate made large dilution effect resulting lower effect of end product inhibition. We have then developed the system by which higher dilution rate could be formed and lower residual substrate concentration would be maintained. The high cell density culture using the cell recycling with hollow fiber filter module met this purpose. This system obtained high ethanol productivity of 26 g/lh with residual glucose concentration of 0.9 g/l at cell mass concentration of 5 g/l.In previous work of continuous ethanol fementation, the highest productivity was reported as 18 g/lh in immobilized Zymomonas mobilis. Therefore, our results obtained in this project is the highest record in the world. Cell entrapped immobilization requires much cost, and it is also difficult to replace old and inactivate cell with fresh one. Ethanol fermentation employing Zymomonas mobilis is efficient that the fermentation attains high ethanol productivity with low cell mass concentration so that the conventional fermentation such as cell suspension saves substrate loss to replace old cell with fresh cell. It is confirmed that this system can operate continuous fermentation with active fresh cell without cell immobilization and can maintain lower substrate concentration. This method may be applied to industry if economical law material is available.
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