ABSTRACT
Aim: In this study, effectiveness of alkali pretreatment of banana pseudostem for the production of biobutanol by fermentation using Clostridium sporogenes under strict anaerobic conditions was studied. Methodology: Banana pseudostem was pretreated by alkali soaking at constant temperature (30, 50 and 70°C) and concentration of 0.25 to 2% (w/v) at solid to liquid ratio of 1:10 for 24 hr to depolymerize the lignocellulosic biomass. Further to increase delignification, the alkali soaked samples were subjected to thermal treatment at 121°C for 15 min. The hydrolysates were subjected to acetone-butanol-ethanol fermentation using Clostridium sporogenes to produce butanol. Results: Maximum delignification of 92% was obtained at 30°C soaking temperature with 2% NaOH (w/v). Increase in temperature led to increase in delignification but also resulted in reduced recovery of cellulose. Maximum glucose yield of 524 mg g-1 glucan was obtained from the pretreated biomass. Fermentation of hydrolysate obtained from alkali soaking pretreatment by C. sporogenes under anaerobic condition resulted in 10.12 g l-1 of butanol with a yield of 0.326 g g-1 of total sugar consumed and it was much higher compared to untreated biomass. Interpretation: Alkali soaking pretreatment at 30°C and alkali concentration of 1.5% (w/v) was effective to depolymerize the biomass to obtain maximum sugar and butanol yield from banana pseudostem. Thermal treatment was not effective in increasing the production of butanol due to pseudo lignin formation and presence of inhibitors.
ABSTRACT
Salviae Miltiorrhizae Radix et Rhizoma residues were pre-treated with acid and alkali, degraded by using cellulose, and the effects of different processing methods on the extraction rate of tanshinones were compared to provide scientific basis for development and utilization of tanshinones from Salviae Miltiorrhizae Radix et Rhizoma residues. The results showed that in the Salviae Miltiorrhizae Radix et Rhizoma residues without pre-treatment, enzymatic hydrolysis time of 4.5 d could make most of the cellulose degraded when the concentration of substrate enzyme concentration was 6 U•mL-1, and the highest glucose concentration was 59.74 mg•g⁻¹. It was found that the best effect was achieved after alkali pre-treatment-cellulose C degradation among the different pre-treatment methods, and the glucose content reached 119.50 mg•g⁻¹, followed by the same concentration of acid pre-treatment-cellulose C degradation. The extraction amount of tanshinone ⅡA was increased by 82.54% after enzyme degradation, with a mass fraction of 2.451 mg•g⁻¹; extraction amount of tanshinone I was increased by 81.82% after enzyme degradation, with a mass fraction of 2.373 mg•g⁻¹; extraction amount of cryptotanshinone was increased by 64.4% after enzyme degradation, with a mass fraction of 1.080 mg•g⁻¹; extraction amount of dihydrotanshinone I was increased by 61.3% after enzyme degradation, with a mass fraction of 0.601 2 mg•g⁻¹. Acid and alkali pre-treatment combined with cellulose degradation could effectively improve the extraction rate of tanshinones from Salviae Miltiorrhizae Radix et Rhizoma residues. This method is operable and practical, and it is beneficial for improving the utilization efficiency of tanshinones (resource based chemicals) from Salviae Miltiorrhizae Radix et Rhizoma residues.