Presenting the possibility of eliminating the pretreatment step from cellulosic biofuel production, a hot springs bacterium known as Caldicellulosiruptor bescii has shown that it can efficiently degrade crystalline cellulose, xylan (a hemicellulose), and various types of non-pretreated biomass including hardwoods such as poplar, high-lignin grasses such as switchgrass, and low-lignin grasses such as Bermuda grass. With an optimal growth temperature of 75 celsius, C. bescii was able to break down 65% of switchgrass biomass without pretreatment. This bacterium is the most heat-tolerant biomass degrader known (withstanding temperatures up to 90 celsius), and it primarily produces hydrogen as an end product when grown on plant biomass.
Credit or Source: Image courtesy of Mike Adams, University of Georgia
US DOE. 2010. Bioenergy Research Centers: An Overview of the Science, DOE/SC-0127, US Department of Energy. (p. 19) (website)