Rice straw pretreatment was examined in a full factorial study at temperatures of 120 C
and 160 C and 0% and 1% [H2SO4]. Pretreatment efficacy was assessed by measuring hydrolysate
composition and reducing sugar yield after enzymatic hydrolysis. Pretreatment
with 1% [H2SO4] and 160 C yielded the highest amount of reducing sugar, 259 mg g1 [dry
matter], during enzymatic hydrolysis corresponding to 57% glucose conversion based on
cellulose content of the pretreated solid. Under this pretreatment condition hydroxymethylfurfural
and furfural were 0.19 and 0.68 g l1, respectively. Rice straw pretreated
with 1% [H2SO4] at 160 C was subjected to simultaneous saccharification and fermentation
(SSF) using either Saccharomyces cerevisiae D5A or recombinant Escherichia coli KO11. Solid
and hydrolysate separation and washing techniques were evaluated for their effect on
ethanol production during SSF. Pretreated rice straw without liquidesolid separation or
washing had the highest 7-d ethanol yield of 0.2 g [ethanol] g1 [dry substrate] for E. coli
KO11. This finding has economic implications on the processing of rice straw to bioethanol.