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Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein
BACKGROUND: Liquid hot water (LHW) pretreatment has been considered as one of the most industrially viable and environment-friendly methods for facilitating the transformation of lignocelluloses into biofuels through biological conversion. However, lignin fragments in pretreatment hydrolysates are p...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6417190/ https://www.ncbi.nlm.nih.gov/pubmed/30911331 http://dx.doi.org/10.1186/s13068-019-1387-x |
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author | Luo, Xiaolin Liu, Jing Zheng, Peitao Li, Meng Zhou, Yang Huang, Liulian Chen, Lihui Shuai, Li |
author_facet | Luo, Xiaolin Liu, Jing Zheng, Peitao Li, Meng Zhou, Yang Huang, Liulian Chen, Lihui Shuai, Li |
author_sort | Luo, Xiaolin |
collection | PubMed |
description | BACKGROUND: Liquid hot water (LHW) pretreatment has been considered as one of the most industrially viable and environment-friendly methods for facilitating the transformation of lignocelluloses into biofuels through biological conversion. However, lignin fragments in pretreatment hydrolysates are preferential to condense with each other and then deposit back onto cellulose surface under severe conditions. Particularly, lignin tends to relocate or redistribute under high-temperature LHW pretreatment conditions. The lignin residues on the cellulose surface would result in significant nonproductive binding of cellulolytic enzymes, and therefore negatively affect the enzymatic conversion (EC) of glucan in pretreated substrates. Although additives such as bovine serum albumin (BSA) and Tween series have been used to reduce nonproductive binding of enzymes through blocking the lignin, the high cost or non-biocompatibility of these additives limits their potential in industrial applications. RESULTS: Here, we firstly report that a soluble soy protein (SP) extracted from inexpensive defatted soy powder (DSP) showed excellent performance in promoting the EC of glucan in LHW-pretreated lignocellulosic substrates. The addition of the SP (80 mg/g glucan) could readily reduce the cellulase (Celluclast 1.5 L(®)) loading by 8 times from 96.7 to 12.1 mg protein/g glucan and achieve a glucan EC of 80% at a hydrolysis time of 72 h. With the same cellulase (Celluclast 1.5 L(®)) loading (24.2 mg protein/g glucan), the ECs of glucan in LHW-pretreated bamboo, eucalyptus, and Masson pine substrates increased from 57%, 54% and 45% (without SP) to 87%, 94% and 86% (with 80 mg SP/g glucan), respectively. Similar effects were also observed when Cellic CTec2, a newer-generation cellulase preparation, was used. Mechanistic studies indicated that the adsorption of soluble SP onto the surface of lignin residues could reduce the nonproductive binding of cellulolytic enzymes to lignin. The cost of the SP required for effective promotion would be equivalent to the cost of 2.9 mg cellulase (Celluclast 1.5 L(®)) protein (or 1.2 FPU/g glucan), if a proposed semi-simultaneous saccharification and fermentation (semi-SSF) model was used. CONCLUSIONS: Near-complete saccharification of glucan in LHW-pretreated lignocellulosic substrates could be achieved with the addition of the inexpensive and biocompatible SP additive extracted from DSP. This simple but remarkably effective technique could readily contribute to improving the economics of the cellulosic biorefinery industry. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13068-019-1387-x) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-6417190 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-64171902019-03-25 Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein Luo, Xiaolin Liu, Jing Zheng, Peitao Li, Meng Zhou, Yang Huang, Liulian Chen, Lihui Shuai, Li Biotechnol Biofuels Research BACKGROUND: Liquid hot water (LHW) pretreatment has been considered as one of the most industrially viable and environment-friendly methods for facilitating the transformation of lignocelluloses into biofuels through biological conversion. However, lignin fragments in pretreatment hydrolysates are preferential to condense with each other and then deposit back onto cellulose surface under severe conditions. Particularly, lignin tends to relocate or redistribute under high-temperature LHW pretreatment conditions. The lignin residues on the cellulose surface would result in significant nonproductive binding of cellulolytic enzymes, and therefore negatively affect the enzymatic conversion (EC) of glucan in pretreated substrates. Although additives such as bovine serum albumin (BSA) and Tween series have been used to reduce nonproductive binding of enzymes through blocking the lignin, the high cost or non-biocompatibility of these additives limits their potential in industrial applications. RESULTS: Here, we firstly report that a soluble soy protein (SP) extracted from inexpensive defatted soy powder (DSP) showed excellent performance in promoting the EC of glucan in LHW-pretreated lignocellulosic substrates. The addition of the SP (80 mg/g glucan) could readily reduce the cellulase (Celluclast 1.5 L(®)) loading by 8 times from 96.7 to 12.1 mg protein/g glucan and achieve a glucan EC of 80% at a hydrolysis time of 72 h. With the same cellulase (Celluclast 1.5 L(®)) loading (24.2 mg protein/g glucan), the ECs of glucan in LHW-pretreated bamboo, eucalyptus, and Masson pine substrates increased from 57%, 54% and 45% (without SP) to 87%, 94% and 86% (with 80 mg SP/g glucan), respectively. Similar effects were also observed when Cellic CTec2, a newer-generation cellulase preparation, was used. Mechanistic studies indicated that the adsorption of soluble SP onto the surface of lignin residues could reduce the nonproductive binding of cellulolytic enzymes to lignin. The cost of the SP required for effective promotion would be equivalent to the cost of 2.9 mg cellulase (Celluclast 1.5 L(®)) protein (or 1.2 FPU/g glucan), if a proposed semi-simultaneous saccharification and fermentation (semi-SSF) model was used. CONCLUSIONS: Near-complete saccharification of glucan in LHW-pretreated lignocellulosic substrates could be achieved with the addition of the inexpensive and biocompatible SP additive extracted from DSP. This simple but remarkably effective technique could readily contribute to improving the economics of the cellulosic biorefinery industry. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13068-019-1387-x) contains supplementary material, which is available to authorized users. BioMed Central 2019-03-13 /pmc/articles/PMC6417190/ /pubmed/30911331 http://dx.doi.org/10.1186/s13068-019-1387-x Text en © The Author(s) 2019 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Luo, Xiaolin Liu, Jing Zheng, Peitao Li, Meng Zhou, Yang Huang, Liulian Chen, Lihui Shuai, Li Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
title | Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
title_full | Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
title_fullStr | Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
title_full_unstemmed | Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
title_short | Promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
title_sort | promoting enzymatic hydrolysis of lignocellulosic biomass by inexpensive soy protein |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6417190/ https://www.ncbi.nlm.nih.gov/pubmed/30911331 http://dx.doi.org/10.1186/s13068-019-1387-x |
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