Palm kernel cake (PKC), a by-product of palm oil industry, contains glucose and mannose as hexose sugars. This study was performed to determine the feasibility of using PKC as a lignocellulosic substrate for biobutanol production by Clostridium saccharoperbutylacetonicum N1-4 in an acetone-butanol-ethanol (ABE) fermentation process. Moreover, the effect of tryptone-yeast extract-acetate (TYA) medium and P2 medium on biobutanol production was evaluated. Experimental results showed that butanol production of 3.05 g/L was obtained using mannose sugar, which was comparable to 3.61 g/L butanol production measured using glucose. Moreover, the maximum production of biobutanol (0.38 g/L) was obtained at a PKC concentration of 30%, indicating the possibility of PKC utilization in butanol production. ABE fermentation of PKC using distilled water, TYA medium, and P2 medium showed that the highest butanol production (0.26 g/L) with ABE production of 0.38 g/L was obtained when ABE fermentation was conducted in P2 medium.

In this study, response surface methodology (RSM) was applied to optimize and investigate the ability of yeast extract, CaCO3, MgSO4, and K2HPO4 to maximize biobutanol production by a novel local isolate of Clostridium acetobutylicum YM1. A central composite design was applied as the experimental design, and analysis of variance (ANOVA) was used to analyze the experimental data. A quadratic polynomial equation was obtained for biobutanol production by multiple regression analysis. ANOVA analysis showed that the model was significant (p < 0.0001), and the yeast extract, CaCO3, and MgSO4 concentrations had a significant effect on biobutanol production. However, K2HPO4 did not have a significant effect on biobutanol production. The estimated optimum combinations for biobutanol production using C. acetobutylicum YM1 were 2 g/L yeast extract, 6 g/L CaCO3, 0.1 g/L MgSO4, and 1.1 g/L K2HPO4. Subsequently, the model was validated through use of the estimated optimum conditions, which confirmed the model validity and 13.67 g/L of biobutanol was produced.