BACTERIA-BASED BIOMASS-TO-ETHANOL PROCESS IS OPTIMIZED

At the World Congress on Industrial Biotechnology and Bioprocessing in Orlando, FL (Apr. 19-22, 2005), Univ. of Florida (UFL; Gainesville; www.ufl.edu) microbiology professor Lonnie Ingram unveiled a new technology that can be used to produce ethanol for about $1.30/gal - genetically engineered E. coli bacteria that convert biomass and other farm wastes into fuel ethanol at yields of 90-95%.

The organisms were created by cloning two genes from Zymomonas mobilis (Z. mobilis) and inserting them into the E coli. "The gene adhB encodes for alcohol dehydrogenase B (ADHB), while pdc encodes for pyruvate decarboxylase (PDC)," explains Ingram. "This replaces the fermentation-acid producing pathways in E coli with the alcohol-producing pathway in Z. mobilis," he adds. PDC converts pyruvic acid, the common intermediate in all sugar metabolism, to carbon dioxide and acetaldehyde. ADH converts the acetaldehyde to ethanol. Like yeast, Z. mobilis is limited in the types of sugars it can metabolize, but is ideal for making ethanol. E coli is able to metabolize all plant sugars, but normally makes a mixture of acids as products. "Our work combined the best of both organisms," says Ingram.

This bioconversion technology, selected by the U.S. Dept. of Commerce to become Landmark Patent No. 5,000,000, is being commercialized with help from the U.S. Dept. of Energy (DOE; Washington, DC; www.doe.gov). BC International Corp. (BCI; Dedham, MA; www.bcintlcorp. com), which holds exclusive rights to use and license the UFL-engineered bacteria, plans to build a 30-million gal/yr biomass-to-ethanol plant in Jennings, LA, based on Ingram's microbial platform. Slated to start up in late 2006, the facility will process wastes from Louisiana's sugarcane industry and produce ethanol for industrial chemical and clean-burning fuel applications, according to Greg LuIi, vice president of research for BC International's laboratory in Alachua, FL. "Other potential feedstocks include rice hulls, forestry and wood wastes," adds Ingram.

"To date, all of the world's fuel ethanol has been produced from high-value materials such as cornstarch and cane syrup using yeast fermentations," says Ingram. "The chemical makeup of biomass prevented it from being used to make ethanol economically, until now. "Ingram underscores the impact of his bioengineering innovation with a report by the U.S. Dept. of Agriculture and DOE, which states that more than 1 billion ton/y of biomass can be produced on a sustainable basis. "Converting this to fuel ethanol, now a very real possibility, could replace half of all imported petroleum in the U.S."