Wheat straw was pretreated in a 2 L beaker covered with aluminium foil. After that ,wait for the mixture was cooled, adjust pH to 6.5 with 10 M NaOH. Next, take the mixture into 2.5 L bioreactor and add 10 mL of autoclaved yeast extract solution and 10 mL of P2 stock solutions. Process conducted under anaerobic condition