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Alkaline organosolv pretreatment of different sorghum stem parts for enhancing the total reducing sugar yields and p-coumaric acid release
shaojun Ding
Nanjing Forestry University
Corresponding Author
ORCiD: https://orcid.org/0000-0002-8359-9252
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: The sorghum stem can be divided into the pith and rind parts with obvious differences in cell type and chemical composition, thus arising the different recalcitrance to enzyme hydrolysis and demand for different pretreatment conditions. The introduction of organic solvents in the pretreatment can reduce over-degradation of cellulose and hemicellulose, but significance of organic solvent addition in pretreatment of different parts of sorghum stem is still unclear. Valorization of each component is critical for economy of sorghum biorefinery. Therefore, in this study, NaOH-ethanol pretreatment condition for different parts of the sorghum stem was optimized in order to maximize p-coumaric acid release and total reducing sugar recovery.
Result: Ethanol addition improved p-coumaric acid release and delignification efficiency, but significantly reduced hemicellulose deconstruction in NaOH-ethanol pretreatment. Optimization using the response surface methodology revealed that the pith, rind and whole stem require different NaOH-ethanol pretreatment conditions for maximal p-coumaric acid release and xylan preservation. By respective optimal NaOH-ethanol pretreatment, the p-coumaric acid release yields reached 94.07%, 97.24% and 95.05% from pith, rind and whole stem, which increased by 8.16%, 8.38% and 8.39% compared to those of NaOH pretreated samples. The xylan recoveries of pith, rind and whole stem reached 76.80%, 88.46% and 85.01%, respectively, which increased by 47.75%, 15.11% and 35.97% compared to NaOH pretreatment. Adding xylanase significantly enhanced the enzymatic saccharification of pretreated residues. The total reducing sugar yields after respective optimal NaOH-ethanol pretreatment and enzymatic hydrolysis reached 84.06%, 82.29% and 84.09% for pith, rind and whole stem, respectively, which increased by 29.56%, 23.67% and 25.56% compared to those of NaOH pretreated samples. Considering the separation cost of the different stem parts, whole sorghum stem can be directly used as feedstock in industrial biorefinery.
Conclusion: These results indicated that NaOH-ethanol is effective for the efficient fractionation and pretreatment of sorghum biomass. This work will help to understand the differences of different parts of sorghum stem under NaOH-ethanol pretreatment, thereby improving the full-component utilization of sorghum stem.
Keywords
Sorghum stem; NaOH-ethanol pretreatment; p-coumaric acid; enzymatic hydrolysis.
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This preprint is under consideration at Biotechnology for Biofuels. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Alkaline organosolv pretreatment of different sorghum stem parts for enhancing the total reducing sugar yields and p-coumaric acid release
shaojun Ding
Nanjing Forestry University
Corresponding Author
ORCiD: https://orcid.org/0000-0002-8359-9252
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 3
Posted 04 Jun, 2020
No community comments so far
Editor assigned
On 28 May, 2020
Submission checks complete
On 27 May, 2020
Editor invited
On 27 May, 2020
No comments provided
Editorial decision: Minor revision
On 11 May, 2020
Review #2 received
Received 08 May, 2020
Reviewer #2 agreed
On 02 May, 2020
Review #1 received
Received 01 May, 2020
Reviewers invited
Invitations sent on 27 Apr, 2020
Reviewer #1 agreed
On 27 Apr, 2020
Editor assigned
On 25 Apr, 2020
Submission checks complete
On 24 Apr, 2020
Editor invited
On 24 Apr, 2020
No comments provided
Editorial decision: Major revision
On 02 Apr, 2020
Review #2 received
Received 01 Apr, 2020
Review #1 received
Received 29 Mar, 2020
Reviewer #1 agreed
On 17 Mar, 2020
Reviewer #2 agreed
On 17 Mar, 2020
Reviewers invited
Invitations sent on 16 Mar, 2020
Editor invited
On 14 Mar, 2020
Editor assigned
On 14 Mar, 2020
First submitted
On 13 Mar, 2020
Submission checks complete
On 13 Mar, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Biochemical Research Methods
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: The sorghum stem can be divided into the pith and rind parts with obvious differences in cell type and chemical composition, thus arising the different recalcitrance to enzyme hydrolysis and demand for different pretreatment conditions. The introduction of organic solvents in the pretreatment can reduce over-degradation of cellulose and hemicellulose, but significance of organic solvent addition in pretreatment of different parts of sorghum stem is still unclear. Valorization of each component is critical for economy of sorghum biorefinery. Therefore, in this study, NaOH-ethanol pretreatment condition for different parts of the sorghum stem was optimized in order to maximize p-coumaric acid release and total reducing sugar recovery.
Result: Ethanol addition improved p-coumaric acid release and delignification efficiency, but significantly reduced hemicellulose deconstruction in NaOH-ethanol pretreatment. Optimization using the response surface methodology revealed that the pith, rind and whole stem require different NaOH-ethanol pretreatment conditions for maximal p-coumaric acid release and xylan preservation. By respective optimal NaOH-ethanol pretreatment, the p-coumaric acid release yields reached 94.07%, 97.24% and 95.05% from pith, rind and whole stem, which increased by 8.16%, 8.38% and 8.39% compared to those of NaOH pretreated samples. The xylan recoveries of pith, rind and whole stem reached 76.80%, 88.46% and 85.01%, respectively, which increased by 47.75%, 15.11% and 35.97% compared to NaOH pretreatment. Adding xylanase significantly enhanced the enzymatic saccharification of pretreated residues. The total reducing sugar yields after respective optimal NaOH-ethanol pretreatment and enzymatic hydrolysis reached 84.06%, 82.29% and 84.09% for pith, rind and whole stem, respectively, which increased by 29.56%, 23.67% and 25.56% compared to those of NaOH pretreated samples. Considering the separation cost of the different stem parts, whole sorghum stem can be directly used as feedstock in industrial biorefinery.
Conclusion: These results indicated that NaOH-ethanol is effective for the efficient fractionation and pretreatment of sorghum biomass. This work will help to understand the differences of different parts of sorghum stem under NaOH-ethanol pretreatment, thereby improving the full-component utilization of sorghum stem.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5