3 Biotech

, 9:455 | Cite as

Optimization of pre-saccharification time during dSSF process in oat-hull bioethanol technology

  • Galina F. MironovaEmail author
  • Ekaterina A. Skiba
  • Aleksey A. Kukhlenko
Original Article


This study suggests a mathematical description and the optimization of the pre-saccharification time during simultaneous saccharification and fermentation with delayed yeast inoculation (dSSF) to ensure the fastest and fullest possible conversion of a substrate into the target product—bioethanol. A pulp derived by alkaline delignification of oat hulls was used as a substrate. The pre-saccharification step of oat-hull pulp was performed at a solid loading of 60 g/L, at 46 ± 2 °C, using mixed enzymes CelloLux-A and BrewZyme BGX, the pre-saccharification time was 8, 15, 24, 39, 48 and 72 h. Afterwards, the reaction mixture was cooled to 28 °C, a 10% inoculum of Saccharomyces cerevisiae Y-1693 was seeded, and fermentation combined with saccharification. The optimum pre-saccharification time (inoculation time) under these conditions was found to be 24 h, thus providing the maximum hydrolysis of cellulose and hemicelluloses and the highest yield of bioethanol. The procedure suggested herein for determining the optimum pre-saccharification time can be used for other model substrates from lignocellulosic feedstocks.


Oat hulls Pre-saccharification dSSF model Bioethanol 

Abbreviations and List of symbols


Concentration of reducing sugars (g/L)


Concentration of substrate (g/L)


Initial concentration of substrate (g/L)


Concentration of enzyme–substrate complex (g/L)


Final concentration of reducing sugars after 72-h enzymatic hydrolysis (g/L)


Concentration of unutilized reducing sugars for bioethanol production (g/L)


Concentration of unutilizable reducing sugars for bioethanol production (g/L)


Concentration of utilizable reducing sugars for bioethanol production (g/L)


Concentration of utilized reducing sugars for bioethanol production (g/L)


Simultaneous saccharification and fermentation with delayed inoculation


Bioethanol concentration (g/L)


Coefficient of the proportion of unutilizable reducing sugars for bioethanol production


Formation rate of enzyme–substrate complex (h−1)


Breakdown rate of enzyme–substrate complex (g/(L h))


Formation rate of reducing sugars (g/(L h))


Fermentation rate of utilizable reducing sugars for bioethanol production (h−1)


Theoretical yield of bioethanol from sugars (g/g)


Reducing sugars


Separate hydrolysis and fermentation


Simultaneous saccharification and fermentation


Total process time (h)


Enzymatic hydrolysis time (inoculation time) (h)


Bioethanol yield on a substrate weight basis (g/g)



This study was conducted under the State Assignment Program with Theme Registration no. AAAA-A17-117011910006-5.

Author contributions

GFM and EAS designed and performed experiments on bioethanol synthesis, and AAK did mathematical modeling.

Compliance with ethical standards

Conflict of interest

The authors declare no conflict of interest.


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Copyright information

© King Abdulaziz City for Science and Technology 2019

Authors and Affiliations

  1. 1.Laboratory of Bioconversion, Laboratory of Chemical Engineering Processes and Apparatuses, Institute for Problems of Chemical and Energetic TechnologiesSiberian Branch of the Russian Academy of Sciences (IPCET SB RAS)BiyskRussia

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