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Keywords:

  • enzymatic hydrolysis;
  • cellulase;
  • xylanase;
  • RSM;
  • wheat straw

Abstract

BACKGROUND: The enzymatic hydrolysis of steam-exploded wheat straw using commercial enzyme complexes has been studied. A cellulase enzyme complex (Accellerase 1500), along with specific xylanase complements (Accellerase-XC and Accellerase-XY) provided by Genencor, have been used to enhance glucose and xylose recovery.

A systematic study with response surface methodology (RSM) was used to check the effect of the operating conditions: pH (4–5), temperature (50–60 °C) and enzyme/substrate ratio (0.1–0.5 mL gcellulose−1) on the enzymatic hydrolysis with Acellerase 1500 to maximize the sugar yield. Xylanases were used as complements to increase the release of xylose.

RESULT: Statistical results from ANOVA analysis demonstrated that the enzymatic hydrolysis was clearly improved by temperature and enzyme/substrate ratio. The optimum conditions for higher glucose and xylose releases were obtained with the higher enzyme dosage ratio (0.5 mL g−1cellulose), 50 °C and pH 4.

CONCLUSION: Model validation at optimum operating conditions showed good agreement between the experimental results and the predicted responses for a confidence level of 95%.

The use of the xylanase complements, Accellerase-XY (accessory xylanase enzyme complex) and Accellerase-XC (accessory xylanase/cellulase enzyme complex), increases the conversion of hemicellulose. Accellerase-XC supplementation was more effective, obtaining an increase in yields of glucose and xylose of 11.8% and 23.6%, respectively, using a dosage of 0.125 mL g−1cellulose. © 2012 Society of Chemical Industry