Binary- and triple-enzyme cocktails and their application mode affect fermentable sugar release from pretreated lignocellulo-starch biomass
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Lignocellulo-starch biomass (LCSB) comprising roots and vegetable processing wastes has high starch besides cellulose and hemicelluloses and warrants different pretreatment and saccharification approaches. The fermentable sugar yield from steam/dilute sulphuric acid (DSA)-pretreated biomass during saccharification with binary [cellulase + amylolytic enzyme (Stargen)] or triple (cellulase + xylanase + Stargen) enzyme cocktails was compared. The factors such as pH (5.0), temperature (50 °C) and enzyme dosage (16 FPU/g cellulose) for cellulase (Ecozyme RT80) action were optimized using response surface methodology. As pretreated liquor is rich in sugars, whole slurry saccharification was needed for LCSBs and saccharification efficiency (120 h) was significantly higher for steam-pretreated biomass with all application modes. Preferential hydrolysis of starch in steam-pretreated biomass by Stargen followed by cellulolysis was advantageous than the application sequence with cellulase followed by Stargen. Triple-enzyme-based saccharification of steam-pretreated biomass significantly enhanced the overall conversion efficiency (OCE; 85–98%) compared to only 28–49% in the native untreated biomass, while lower OCE was observed in the case of DSA-pretreated and saccharified biomass. Supplementation with both xylanase and Stargen pronouncedly enhanced the OCE for steam-pretreated biomass with only insignificant difference between the exposure periods, indicating the obligatory need for both enzymes for optimal saccharification of LCSBs.
KeywordsLignocellulo-starch biomass Pretreatment Saccharification Enzyme cocktails Application mode Fermentable sugars
The authors acknowledge with gratitude the financial support from the Kerala State Council for Science, Technology & Environment (Grant no. 853/2015/KSCSTE) and the facilities provided by the director, ICAR-CTCRI, for the study. Stargen™ 002 was received by courtesy from M/s Danisco US Inc., USA.
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Conflict of interest
The authors declare that they have no conflict of interest.
- 9.Taherzadeh MJ, Karimi K (2007) Enzyme-based hydrolysis process for ethanol production from lignocellulosic materials: a review. Bioresources 2(4):707–738Google Scholar
- 10.Leu SY, Zhu JY (2013) Substrate-related factors affecting enzymatic saccharification of lignocelluloses: our recent understanding. Bioener Res 6. doi: 10.1007/s12155-012 9286-1
- 24.Mithra MG, Padmaja G (2016 a) Compositional profile and ultrastructure of steam and dilute sulfuric acid pretreated root and vegetable processing residues. Curr Biotechnol 7. doi: 10.2174/2211550105666160916124120
- 25.Mithra MG, Padmaja G (2016 b) Lime pretreatment associated compositional and ultrastructural changes in selected root and vegetable processing residues. Amer J Biomass Bioener (In press).Google Scholar
- 26.Mithra MG, Padmaja G (2016 c) Comparative alterations in the compositional profile of selected root and vegetable peels subjected to three pretreatments for enhanced saccharification. Ind J Biotechnol (In press).Google Scholar
- 31.Ghose TK (1987) Measurement of cellulase activities. Pure Appl Chem 59:257–268Google Scholar
- 33.Nelson N (1944) A photometric adaptation of the Somogyi method for determination of glucose. J Biol Chem 153:375–380Google Scholar
- 34.Anon (2009) STARGEN™ 002: Granular starch hydrolyzing enzyme for ethanol production. Product information published by Genencor International, a Division of Danisco, Danisco US Inc., Available from: http://www.genencor.com. Accessed December 22, 2014.
- 35.AOAC (1995) Official Methods of Analysis, Sixteenth ed., Washington, DC: Association of Official Analytical Chemists.Google Scholar
- 37.SAS (2010) Cary NC. USA: SAS Institute Inc.Google Scholar
- 52.García-Aparicio MP, Ballesteros M, Manzanares P, Ballesteros I, González A, Negro MJ (2007) Xylanase contribution to the efficiency of cellulose enzymatic hydrolysis of barley straw. Appl Biochem Biotechnol 137–140:353–365Google Scholar