|The RITE strain responsible for fermentation: Corynebacterium glutamicum.|
Collaborative research between the Research Institute of Innovative Technology for the Earth (RITE) and Honda R&D Co., Ltd., the Honda Motor Co., Ltd. subsidiary responsible for research and development, has resulted in technology and process for the production of ethanol from cellulosic soft-biomass such as the leaves and stalks of plants.
The RITE-Honda process uses a bacterial strain developed by RITE that ferments sugar into alcohol and applies Honda engineering technology to enable a “significant increase” in alcohol conversion efficiency in comparison to conventional cellulosic bio-ethanol production processes, according to the partners.
The process consists of the following steps:
Pretreatment to separate cellulose from soft-biomass;
Saccharification of cellulose and hemicellulose;
Fermentation of sugar into ethanol using microorganisms; and
Current approaches allow fermentation inhibitors, collaterally formed primarily during the process of separating cellulose and hemicellulose from soft-biomass, to interfere with the function of microorganisms that convert sugar into alcohol, leading to low ethanol yield. The RITE-Honda process reduces the influence of fermentation inhibitors.
The process is based on the use of an engineered strain of Corynebacterium glutamicum developed by RITE that converts five- (pentose) and six- (hexose) carbon sugars into alcohol.
RITE’s Microbiology Research Group engineered C. glutamicum to broaden its substrate utilization range to include the pentose sugar xylose. The researchers also engineered the bacterium to produce ethanol under oxygen-deprived conditions. Fermentation under such a state reduces or eliminates cellular growth and increases ethanol volumetric productivity.
RITE is also working with cellulases and hemicellulases (enzymes that breakdown celluose and hemicelluose) from Clostridium cellulovorans.
RITE and Honda will pursue research for mass production, including development of systems to integrate the four operations, currently operated independently, into a continuous flow within one plant, recycling energy to pursue energy conservation and cost reduction.
A demonstration project is envisioned within a pilot plant to assess the social compatibility and economic efficiency of the new bio-alcohol production system.
Based on the success of this collaborative research, RITE and Honda will pursue further advancement to establish a bio-refinery for production of not only ethanol, but various industrial commodities including automotive materials from biomass.
Research Institute of Innovative Technology for the Earth (RITE) was established in 1990 by the joint investment of the Japanese government and private enterprises, with the goal of conducting fundamental research on countermeasure technology for global-warming, particularly climate change. It is actively engaged in efforts to stabilize climate change through development of alternative energy research and CO2 sequestration technologies.
“Engineering of a Xylose Metabolic Pathway in Corynebacterium glutamicum”; H. Kawaguchi, A.A. Vertès, S. Okino, M. Inui and H. Yukawa; Appl. Environ. Microbiol. 72: 3418-3428. 2006
“Implementing biofuels on a global scale”; Alain A Vertès, Masayuki Inui, Hideaki Yukawa;; Nature Biotechnology 24, 761 - 764 (01 Jul 2006)
“Metabolic Engineering of Corynebacterium glutamicum for Fuel Ethanol Production under Oxygen-Deprivation Conditions”; Masayuki Inui, Hideo Kawaguchi, Shikiko Murakami, Alain A. Vertès, Hideaki Yukawa; Journal of Molecular Microbiology and Biotechnology 2004; 8:243-254 (DOI: 10.1159/000086705)