Wednesday, July 29, 2009 - 11:00 AM
S102
Ethanol production from waste house wood using ethanologenic E. coli
Naoyuki Okuda, Sugar & Bio Technology Dept., Tsukishima Kikai Co., Ltd., 17-15 Tsukuda 2-chome, Chuo-ku, Tokyo, Japan
In Japan, wood is one of the most adequate and abundant resources of the lignocellulosic materials used for bioethanol production, because the forest comprises 68% of the total land area. Especially, waste house wood (WHW) is promising raw material because the network for collecting WHW has been developed under the law and can be collected at reasonable costs.
We have developed a bioethanol production process by which WHW is hydrolyzed using dilute sulfuric acid and hydrolyzates are fermented by a genetically engineered ethanologenic Escherichia coli KO11. To industrialize the process, there were three problems to be solved: diauxie (slow utilization of pentose in hexose-rich medium), toxic compounds in the hydrolyzate and cost for nutrient. As a practical method, microaerationwas found to be effectiveto improve pentose utilization. Although the toxic compounds were removed partially by overliming (addition of an excess calcium hydroxide), when corn steep liquor (CSL) in the medium was reduced from 4% to 1%, sugar uptake and overall ethanol yield decreased. These decreases probably caused by the residual toxic compounds were overcome by increasing the inoculum size of KO11 or co-culture with yeast.
We have developed a bioethanol production process by which WHW is hydrolyzed using dilute sulfuric acid and hydrolyzates are fermented by a genetically engineered ethanologenic Escherichia coli KO11. To industrialize the process, there were three problems to be solved: diauxie (slow utilization of pentose in hexose-rich medium), toxic compounds in the hydrolyzate and cost for nutrient. As a practical method, microaerationwas found to be effectiveto improve pentose utilization. Although the toxic compounds were removed partially by overliming (addition of an excess calcium hydroxide), when corn steep liquor (CSL) in the medium was reduced from 4% to 1%, sugar uptake and overall ethanol yield decreased. These decreases probably caused by the residual toxic compounds were overcome by increasing the inoculum size of KO11 or co-culture with yeast.
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See more of Invited Oral Papers
See more of The Annual Meeting and Exhibition 2009 (July 26 - 30, 2009)