Development of Acetone Butanol Ethanol (ABE) Production from Palm Pressed Fiber by Mixed Culture of Clostridium sp. and Bacillus sp.

Abstract

Abstract The palm pressed fiber (PPF) was treated either with NaOH 10% (w/v) and boiling for 15 min or H2SO4 0.5% (v/v) and autoclaved at 121 °C for 60 min. The PPF residues after pretreatment with NaOH, H2SO4 and both were 63.28, 62.20 and 47.00% (w/w), respectively. The pretreatment with both NaOH and H2SO4 reduced significantly lignin content and the highest cellulose content of 76.32% (w/w) was obtained. The ABE production using pretreated PPF as a carbon source was attempted in a single culture of Clostridium acetobutylicum DSM 1713 and a mixed culture of C. acetobutylicum DSM 1713 with Bacillus cellulolyticus JCM 9156 with and without addition of cellulase. It was found that the single and mixed cultures with the addition of 30 U cellulase gave the ABE production of 3.97 and 3.95 g/L, respectively, at 144 h. While the cultures without cellulase produced much less ABE (0.25-0.49 g/L). Although, the mixed culture did not improve ABE production, it could reduce the use of reducing agent and nitrogen gas to ensure the anaerobic condition. The optimum condition for ABE production by the mixed culture using pretreated PPF was 5.0 g/L PPF and 9.0 g/ L isolated soy protein (ISP), at pH 6.5, 37 °C, 60 rpm with the addition of 30 U cellulase. At this condition, 4.95 g/L of ABE was obtained at 144 h.