depicts the variations in butanol production, butanol yield
and butanol productivity measured for ABE fermentation of the
hydrolysate sugars obtained from the different enzymatic hydrolysis
methods of PKC. As can be seen from Fig. 2A, the highest butanol
concentration (3.75 ± 0.18 g/L) was produced using the simple
sugar mixture obtained from the enzymatic treatment of PKC by
the combination of three enzymes studied at 168 h ABE. As shown
in Fig. 2A, maximum butanol production using the reducing sugar
mixture obtained from the PKC hydrolysis by the enzyme blend of
cellulase and mannanase was exhibited at 168 h ABE with the
value as high as 3.38 ± 0.86 g/L, while the amount of the butanol
measured at 120 h ABE (3.36 g/L) had no a high difference with
the butanol production at 168 h ABE. In an attempt for the butanol
production by C. saccharoperbutylacetonicum N1-4, it was found
that ABE fermentation of pure mannose and pure glucose using
the same concentration of 30 g/L resulted in the butanol production
with a close concentration of 3.05 g/L and 3.61 g/L from mannose
and glucose, respectively (Shukor et al., 2014b).