Pretreated and enzyme-hydrolyzed peanut shell for cultivation of clostridium sp. g10

Abstract

Peanut shell (PS) is an agricultural residue and generated in large quantities at the peanut processing location. Normally, these lignocellulosic materials are utilized as feed or disposed of to landfill or burnt. In this research, PS was pretreated, enzymatically hydrolyzed, and utilized as a carbon source for Clostridium sp. G10 to produce butanol through acetone-butanol-ethanol (ABE) fermentation. PS was pretreated with H2SO4 and NaOH (0- 1.0M). The highest reducing sugar concentration in the supernatant obtained from 0.4M H2SO4 was 23.1 g/L. Subsequently, the solid portion of pretreated PS was hydrolyzed at 50 °C for 24 h using commercial cellulose (ACCELLERASE™ 1500) with various treatment times duration and enzyme activity to solid ratios. The result suggested that enzyme activityof pretreated PS weight ratio of 1250 carboxymethyl cellulose (CMC) U:1 g yielded the maximum concentration of reducing sugars(12.74 g/L). Mixture of acidic pretreatment hydrolysate and enzyme hydrolysate contained41.2 g/L glucose concentration. Clostridium sp. G10 was then cultured in three conditions; T6 medium with 45 g/L glucose as a control, T6 medium prepared with 45 g/L reducing sugar equivalent of PS hydrolysate, and PS hydrolysate with 45 g/L reducing sugar equivalent at 37°C for 168 h. The implementation ofPS hydrolysate solely as a carbon source produced the butanol concentration of 10.8 g/L. This was not significantly different (p < 0.05) from using T6 medium with glucose (9.3 g/L). The highest butanol production of 15.2 g/Lwas yielded from T6 medium with PS hydrolysate. It could be concluded that hydrolyzed PS could be utilized as a carbon source for production of butanol and ethanol.