Metabolic Engineering of Caldicellulosiruptor bescii for the Production of Biofuels and Bioproducts

Application (Product) Engineeredorganisms for the high temperature conversion of cellulosic biomass intobiofuels and bioproducts. Problems Addressed    (benefits/advantages)Biomass is a renewable resource that can be processed into myriadof chemicals and has shown promise to replace petroleum-based fuels and othermaterials.  Sugars contained withinnaturally occurring biomass can be transformed into ethanol and otherproducts.   However, the cost ofbiomass-based fuels historically has not been competitive relative to oil or otherenergy resources.  The biochemicalconversion step, where plant sugar is converted to fuel, has been veryexpensive.  The presence of lignin,lignocellulose and other compounds hinder direct processing of biomass bybacteria, yeasts and enzymes.  Thishindrance, also known as “biomass recalcitrance”, often requires expensivepretreatment of biomass prior to its transformation into useful products suchas biofuels.Caldicellulosiruptorbescii, athermophilic bacterium, has a high affinity for decomposing lignocellulosicbiomass, which includes agricultural residues such as rice straw, switchgrass,as well as hard- and softwoods. Lignocellulosic biomass consists of cellulose, hemicellulose, pectin andlignin.  Caldicellulosiruptor are amongthe most thermophilic and cellulolytic bacteria, which enables them to degradeuntreated biomass.  This characteristicmakes this organism especially appealing to biomass processing.  However, its inability to produce compoundsof economic interest require that the organism be modified in order to enableits use in industrial processes for the production of biofuels and othercommodity chemicals.

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