Optimization of fermentative hydrogen production from hydrolysate of microwave assisted sulfuric acid pretreated oil palm trunk by hot spring enriched culture

The optimum condition for hydrolysis of oil palm trunk (OPT) by microwave-H2SO4 method and hydrogen production from OPT hydrolysate were explored using response surface methodology (RSM) with central composite design (CCD). The optimum condition for hydrolysis of OPT was 1.56% (w/v) H2SO4 and 7.50 min reaction time at 450 W. At this condition, 8.95±0.99 g/L glucose/L, 8.29±0.43 g/L xylose, 4.57±0.14 g/L arabinose and 2.61±0.11 g/L acetic were obtained. The individual and interactive effects of the initial pH, initial substrate concentration and NaHCO3 concentration on the hydrogen production potential (Ps) from OPT hydrolysate by hot spring enriched culture were further investigated using RSM with CCD. The initial pH and initial substrate concentration had a statistically individual effect on Ps, while the interactive effect on Ps was found between the initial pH and initial substrate concentration. The optimum condition obtained was an initial pH of 6.03, an initial substrate concentration of 22.07 g/L and a NaHCO3 concentration of 6.71 g/L in which a Ps of 1947 mL H2/L medium was achieved. Microbial community analysis by PCR-DGGE indicated that Clostridium sp. and Lactobacillus sp. were the predominant species at the optimum condition.