An enhanced inhibitor-tolerant strain of Pichia stipitis was successfully developed through adaptation to
acid-treated rice straw hydrolysate. The ethanol production obtained by fermentation of NaOH-neutralized
hydrolysate without detoxification using the adapted P. stipitis was comparable to fermentation of
overliming-detoxified hydrolysate. The ethanol yield using the adapted P. stipitis with both types of
hydrolysate at pH 5.0 achieved 0.45 gp gs
1, which is equivalent to 87% of the maximum possible ethanol
conversion. Furthermore, the newly adapted P. stipitis demonstrated significantly enhanced tolerance to
sulfate and furfural despite the fact that both inhibitors had not been removed from the hydrolysate by
NaOH neutralization. Finally, the ethanol conversion could be maintained at 60% and above when the
neutralized hydrolysate contained 3.0% sulfate and 1.3 g L1 furfural.