In 2001, jointly with Marubeni Corporation, Tsukishima Kikai introduced a biomass ethanol technology from Verenium* of the U.S. to put ethanol production processes into practical use to produce ethanol from wood biomass. Wood biomass, including plants and trees, contains cellulose (polymer substance of glucose-C6 sugar) (about 45%), hemicellulose (mainly composed of xylose-C5 sugar) (20% to 30%), and lignin (25%). *Former BCI.

Corn, used as a material in ethanol fermentation, contains starch (70%), which is composed of C6 sugars (Figure 1). Because yeast, widely used in alcohol fermentation, is incapable of converting C5 sugars into ethanol, only C6 sugars have been used for fermentation. It has been difficult to use C5 sugars from wood biomass that contains a relatively large amount of C5 sugars. Thus wood biomass has lower yields, and this has somewhat inhibited its commercialization.

Biomass contains five-carbon sugars, such as xylose, that cannot be fermented by ordinary microorganisms, and has a very low yield.

In the 1980s, Dr. Lonnie O. Ingram at the University of Florida developed a genetically modified strain KO11 based on E. coli bacteria, which enables the conversion of C5 sugars into ethanol. The KO11 strain was developed by injecting a gene from Zymomonas mobilis, a bacterium applicable to alcohol fermentation, into an E. coli bacterium, which can take C5 sugars into itself (Figure 2). Tsukishima Kikai has introduced and improved an ethanol production process based on KO11 to put a biomass-based ethanol production system to practical use (Figure 3). Between fiscal 2001 and 2003, subsidized by NEDO, we implemented "the project on development for the practical use of ethanol production facilities for fuels using construction wood waste."

Features of the BMT Process

• By using both C5 and C6 sugars, the process improves the ethanol yield by 30% to 40% for bagasse and by 20% to 30% for wood compared with conventional methods, thus effectively cutting production costs.
• The E. coli-based KO11 strain has relatively high resistance to impurities, highly fit to the processing of waste biomass.
• Hydrolysis, which converts biomass into sugar content using diluted sulfuric acid, now provides high reliability after undergoing years of study in the U.S.

Figure 3: BMT process flow  
KO11 helps convert C5 sugars into ethanol.
Lignin, which remains after distillation, can be used as a boiler fuel.

In the past, the focus was on the development of technology to convert biomass to fuel. In the future, more attention will be paid to "biomass refinery" which replaces oil-derived products with biomass-derived ones. Studies are intensively carried out to put this technology into practical use for biodegradable plastics and other chemical products. An approach to make various chemical materials from sugar content obtained from wood biomass, using genetically engineered microorganisms is expected. (Figure 4).

Tsukishima Kikai is contributing to the construction of a sustainable society by applying its expertise in machinery production and plant engineering to biomass applications.

By using biotic catalysts, we will be able to make a wide variety of chemical products from biomass (plants and trees), which has great potential as raw material.