Evaluation of four different cultivars of Eucalyptus grandis for the production of ethanol in a Liquefaction plus Simultaneous Saccharification and co-Fermentation (L+SScF) process using ethanologenic bacteria Escherichia coli SY100

Four different cultivars of Eucalyptus grandis, G1, G2, G3, and G5, were pretreated using dilute acid and steam explosion followed by enzymatic saccharification using fungal cellulases in order to determine the potential for ethanol production by the ethanologen Escherichia coli SY100. The pretreatment conditions were previously optimized using a Box-Behnken mathematical model that maximized sugar while keeping inhibitory compounds at a minimum. All four varieties were pretreated using a steam gun at 200 °C, 0.8% w/v phosphoric acid soak, and a 5 min retention time. The cellulase loading was 0.1 mL/g dry weight pretreated biomass using Novozyme® Cellic Ctec2. Of the four varieties, G3 yielded the most total lignocellulosic sugars at 572 g/kg followed by G1 and G5 with 560 g/kg dry weight and G2 with 537 g/kg dry weight. Additional results regarding the use of pretreated slurries in a liquefaction plus simultaneous saccharification and co-fermentation (L+SScF) process will be presented.  All four cultivars have the potential to generate more than 75 gallons of ethanol per ton of biomass.