Enhancement of acetone-butanol-ethanol fermentation from eucalyptus hydrolysate with optimized nutrient supplementation through statistical experimental designs

Eucalyptus has been previously suggested as a potential substrate for acetone-butanol-ethanol (ABE) production without nutrient supplementation; however, incomplete sugar consumption has prevented improvement of ABE production. Cellulase loading with 35 FPU g⁻¹ was first optimized in terms of high hydrolysis efficiency (95%). However, only 0.43 g L⁻¹ ABE production and 3.44% glucose consumption rate were achieved. To improve ABE production from eucalyptus hydrolysate, supplementation of 6 nutrients in common tryptone-yeast extract (TY) medium were investigated by statistical approaches. Three nutrients including yeast extract, tryptone, and FeSO₄·7H₂O were screened as significant nutrients for ABE production. Subsequently, use of a modified TY medium (MTY medium: yeast extract 3.04 g L⁻¹, tryptone 7.64 g L⁻¹, FeSO₄·7H₂O 15.3 mg L⁻¹), which was subsequently predicted by Plackett-Burman and Box-Behnken designs to stimulate ABE production, resulted in ca. 40-fold increase in ABE concentration (16.9 g L⁻¹) and a glucose consumption rate of 100%. We first examined previously uninvestigated nutrition combinations using Plackett-Burman and Box-Behnken designs for high ABE production from eucalyptus hydrolysate. This study shows that statistical method would be a powerful tool for the optimization and enhancement of ABE production from eucalyptus hydrolysate.