Relatively high-substrate consistency hydrolysis of steam-pretreated sweet sorghum bagasse at relatively low cellulase loading

Appl Biochem Biotechnol. 2011 Oct;165(3-4):1024-36. doi: 10.1007/s12010-011-9317-9. Epub 2011 Jul 5.

Abstract

Sweet sorghum bagasse (SSB) was steam pretreated in the conditions of 190 °C for 5 min to assess its amenability to the pretreatment and enzymatic hydrolysis. Results showed that pretreatment conditions were robust enough to pretreat SSB with maximum of 87% glucan and 72% xylan recovery. Subsequent enzymatic hydrolysis showed that the pretreated SSB at 2% substrate consistency resulted in maximum of 70% glucan-glucose conversion. Increasing substrate consistency from 2% to 16% led to a significant reduction in glucan conversion. However, the decrease ratio of glucan-glucose conversion was the minimum when the consistency increased from 2% to 12%. When the pretreated SSB consistency of 12% was applied for hydrolysis, increase in cellulase loading from 7.5 up to 20 filter paper units (FPU)/g glucan resulted only in 14% increase in glucan-glucose conversion compared to 20% increase with cellulase loading varying from 2.5 to 7.5 FPU/g glucan. More than 10 cellobiase units (CBU)/g glucan β-glucosidase supplementation had no noticeable improvement on glucan-glucose conversion. Additionally, supplementation of xylanase was found to significantly increase glucan-glucose conversion from 50% to 80% with the substrate consistency of 12%, when the cellulase and β-glucosidase loadings were at relatively low enzyme loadings (7.5 FPU/g and 10 CBU/g glucan). It appeared that residual xylan played a critical role in hindering the ease of hydrolysis of SSB. A proper xylanase addition was suggested to achieve a high hydrolysis yield at relatively high substrate consistency with relatively low enzyme loadings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biotechnology / methods*
  • Biotransformation
  • Cellulase / metabolism
  • Cellulose / metabolism
  • Endo-1,4-beta Xylanases / metabolism
  • Glucans / metabolism*
  • Glucose / biosynthesis*
  • Hydrolysis
  • Sorghum / metabolism*
  • Steam
  • Sulfur Dioxide / metabolism
  • Xylans / metabolism*
  • beta-Glucosidase / metabolism

Substances

  • Glucans
  • Steam
  • Xylans
  • Sulfur Dioxide
  • Cellulose
  • bagasse
  • beta-Glucosidase
  • Cellulase
  • Endo-1,4-beta Xylanases
  • Glucose