Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Thermophilic gram positive bacteria are a promising alternative to yeast for the ethanolic fermentation of C5 sugars from lignocellulosic biomass. Thermoanaerobacter sp. grows optimally at temperatures around 70 degrees C, allowing for continuous operation over several months, due to the low frequency of contamination at these temperatures. Several strains belonging to the group of Thermoanaerobacter have been genetically modified to increase yield and productivity. No antibiotic resistance encoding genes need to be added to the strains – genes that could otherwise be problematic at production scale. The result is so-called self-cloned strains – strains that contain only their own genes. The fermentation has been scaled up to 250 L and subsequently to 2.5 m3 scale, using industrial solutions, and results show that the thermophilic bacteria compare favorably with yeast, with respect to both ethanol yield and productivity, when grown on lignocellulosic biomass hydrolysates.