Global Biofuel Efforts Expand

Oct. 21, 2013
Korean researchers introduce novel method that uses bacteria to produce gasoline.
Around the world, interest and investment in biofuels continues to grow. For instance, ASB Biodiesel, Hong Kong, announced recently it will generate biodiesel at its Tseung Kwan O processing plant in Hong Kong by year end. The company expects to produce around 100,000 tons/yr of biodiesel, using grease trap waste as feedstock. ASB says it will ship initial output to Europe until domestic demand picks up.[pullquote]In Ireland, a push for a combined bioethanol and sugar industry had its first public fundraising event at the end of September. The goal is to raise €6 million ($8.2 million) to finance the pre-development of a new €400-million ($544-million) sugar and bioethanol facility expected to go online in 2017. In the U.S., the Department of Agriculture awarded General Systems Research, Burlington, Vt., a $51,000 grant under the Commercial Aviation Alternative Fuels Initiative to research the use of waste from dairy farms and beer breweries as a raw material for algae-based biofuels. Other efforts include improving direct-to-ethanol technology and producing bio-based jet fuel from plant sugars (see, "Biofuels Continue to Progress.")And, as CP recently reported, researchers at the University of Massachusetts, Amherst, Mass., have developed a process to make para xylene from lignocellulose ("Renewable Feedstocks Promise Lower Cost p-Xylene,") while initiatives based on algae also are progressing ("Algae Cultivation Technologies Begin to Bloom"). In process development news, in September, the €22-million ($30-million) bioliq pilot plant at the Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany, produced gasoline for the first time. KIT, in cooperation with Chemieanlagenbau Chemnitz, Chemnitz, Germany, has progressed further in the production of environmentally compatible fuels from residual biomass — mostly straw. All stages of the bioliq process — flash pyrolysis, high-pressure entrained-flow gasification, and synthesis — have been realized. So, KIT says the project now will test the entire process chain and optimize it for large-scale industrial use. The hope is that by mid-2014 the bioliq process will be capable of economic large-scale production of high quality gasoline engine fuels.New pilot plants and dedicated technology centers also are speeding progress in bringing to market fuels and other products based on renewable resources and novel coatings and materials (see, "Renewable Resources Drive Pilot Developments," www.chemicalprocessing.com/articles/2012/renewable-resources-drive-pilot-developments/). NEW DEVELOPMENTAnd now Korean scientists are adding another biofuels option in the form of genetically-engineered E. coli bacteria. While E. coli already has been modified to produce long-chain alkanes — containing 13–17 carbon atoms — suitable for replacing diesel, there have been no reports, until recently, on the microbial production of the straight and branched-chain C4–C12 short-chain alkanes (SCAs) that make up gasoline.The team, led by professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST), Daedeok Science Town, developed a novel strategy for microbial gasoline production through metabolic engineering of E. coli.The research team screened enzymes associated with the production of fatty acids and engineered them to provide fatty acid derivatives that are shorter than the normal intracellular fatty acid metabolites. They then introduced a novel synthetic pathway and optimized culture conditions to convert short-chain fatty acids to their corresponding alkanes. This allowed development of an E. coli strain capable of producing gasoline. In addition, this strain, if desired, can be modified by introducing enzymes that can produce other products such as short-chain fatty esters and alcohols. The final engineered strain produced up to 580.8 mg/l of SCAs consisting of nonane (327.8 mg/l, dodecane (136.5 mg/l), tridecane (64.8 mg/l), 2-methyl-dodecane (42.8 mg/l) and tetradecane (8.9 mg/l), together with small amounts of other hydrocarbons. For more details, see their article in the September 29 issue of Nature ("Microbial Production of Short-chain Alkanes")."It is only the beginning of the work towards sustainable production of gasoline. The titer is rather low due to the low metabolic flux towards the formation of short-chain fatty acids and their derivatives. We are currently working on increasing the titer, yield and productivity of bio-gasoline. Nonetheless, we are pleased to report, for the first time, the production of gasoline through the metabolic engineering of E. coli, which we hope will serve as a basis for the metabolic engineering of microorganisms to produce fuels and chemicals from renewable resources," says Lee.
Seán Ottewell is Chemical Processing's Editor at Large. You can e-mail him at [email protected]

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