The second fed-batch fermentation experiment utilized corn
stover that was NaOH-pretreated and subsequently washed with
water. The process was conducted using the same conditions as
those used in the first fed-batch experiment. The washed corn
stover was fed from 18 to 20 h, and the final corn stover concentration
reached 14.4% (w/w). Enzyme feeding was carried out in a
manner similar to that of the first fed-batch experiment, and the
final enzyme concentration was 30 FPU/g stover (Fig. 5C). The LA
titer reached 97.59 g/L, the yield reached 0.68 g/g stover, and the
average productivity was 1.63 g/L/h (Table 1). Another significant
difference between these fed-batch experiments was that the
acetic acid titer in the second experiment was quite low. The final
acetic acid titer was 11.60 g/L, the yield was 0.08 g/g, and the average
productivity was 0.19 g/L/h (Table 1). The final concentrations
of L-LA in SSF of washed and unwashed pretreated corn stover were
98.1% and 97.9%, respectively.