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Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches
BACKGROUND: The lignocellulosic biomass feedstocks such as empty fruit bunches (EFBs) prove to be potential renewable resources owing to their abundance, low prices, and high carbohydrate contents. Generally, the conversion of lignocellulosic biomass into chemicals, fuels, and materials mainly inclu...
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/PMC6551891/ https://www.ncbi.nlm.nih.gov/pubmed/31178926 http://dx.doi.org/10.1186/s13068-019-1476-x |
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author | Kim, Jae Kyun Yang, Jungwoo Park, So Young Yu, Ju-Hyun Kim, Kyoung Heon |
author_facet | Kim, Jae Kyun Yang, Jungwoo Park, So Young Yu, Ju-Hyun Kim, Kyoung Heon |
author_sort | Kim, Jae Kyun |
collection | PubMed |
description | BACKGROUND: The lignocellulosic biomass feedstocks such as empty fruit bunches (EFBs) prove to be potential renewable resources owing to their abundance, low prices, and high carbohydrate contents. Generally, the conversion of lignocellulosic biomass into chemicals, fuels, and materials mainly includes pretreatment, enzymatic hydrolysis, fermentation, and recovery of final products. To increase the economic viability of such processes, the cost of cellulase production and enzymatic hydrolysis should be reduced. For this, recycling cellulase can be considered for reducing the saccharification cost of lignocellulose. In this study, cellulase recycling for high-solids enzymatic hydrolysis (i.e., 20%) was evaluated in saccharification of hydrothermally-pretreated EFBs. RESULTS: High-solids (20%) enzymatic hydrolysis of hydrothermally-pretreated empty fruit bunches with 40 FPU of Cellic CTec3/g glucan was carried out for cellulase recycling. In the second round of hydrolysis using a recycled enzyme, only 19.3% of glucose yield was obtained. The most important limiting factors for cellulase recycling of this study were identified as the enzyme inhibition by glucose, the loss of enzyme activities, and the non-productive binding of enzymes to insoluble biomass solids. To overcome these limitations, PEG was added prior to the first-round hydrolysis to reduce non-productive enzyme binding, glucose was removed from the enzyme fraction to be reused in the second-round hydrolysis, and EFB solids from the first-round hydrolysis were used in the second-round hydrolysis. These three additional measures with cellulase recycling resulted in a 3.5 times higher glucose yield (i.e., 68.0%) at the second round than that of the control, the second-round hydrolysis with cellulase recycling but without these measures. CONCLUSIONS: Because of the high obstacles found in this study in achieving high saccharification yields in the high-solids saccharification of high-lignin lignocellulose with cellulase recycling, effective measures for improving enzymatic saccharification yields need to be accompanied with cellulase recycling. |
format | Online Article Text |
id | pubmed-6551891 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-65518912019-06-07 Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches Kim, Jae Kyun Yang, Jungwoo Park, So Young Yu, Ju-Hyun Kim, Kyoung Heon Biotechnol Biofuels Research BACKGROUND: The lignocellulosic biomass feedstocks such as empty fruit bunches (EFBs) prove to be potential renewable resources owing to their abundance, low prices, and high carbohydrate contents. Generally, the conversion of lignocellulosic biomass into chemicals, fuels, and materials mainly includes pretreatment, enzymatic hydrolysis, fermentation, and recovery of final products. To increase the economic viability of such processes, the cost of cellulase production and enzymatic hydrolysis should be reduced. For this, recycling cellulase can be considered for reducing the saccharification cost of lignocellulose. In this study, cellulase recycling for high-solids enzymatic hydrolysis (i.e., 20%) was evaluated in saccharification of hydrothermally-pretreated EFBs. RESULTS: High-solids (20%) enzymatic hydrolysis of hydrothermally-pretreated empty fruit bunches with 40 FPU of Cellic CTec3/g glucan was carried out for cellulase recycling. In the second round of hydrolysis using a recycled enzyme, only 19.3% of glucose yield was obtained. The most important limiting factors for cellulase recycling of this study were identified as the enzyme inhibition by glucose, the loss of enzyme activities, and the non-productive binding of enzymes to insoluble biomass solids. To overcome these limitations, PEG was added prior to the first-round hydrolysis to reduce non-productive enzyme binding, glucose was removed from the enzyme fraction to be reused in the second-round hydrolysis, and EFB solids from the first-round hydrolysis were used in the second-round hydrolysis. These three additional measures with cellulase recycling resulted in a 3.5 times higher glucose yield (i.e., 68.0%) at the second round than that of the control, the second-round hydrolysis with cellulase recycling but without these measures. CONCLUSIONS: Because of the high obstacles found in this study in achieving high saccharification yields in the high-solids saccharification of high-lignin lignocellulose with cellulase recycling, effective measures for improving enzymatic saccharification yields need to be accompanied with cellulase recycling. BioMed Central 2019-06-06 /pmc/articles/PMC6551891/ /pubmed/31178926 http://dx.doi.org/10.1186/s13068-019-1476-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 Kim, Jae Kyun Yang, Jungwoo Park, So Young Yu, Ju-Hyun Kim, Kyoung Heon Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
title | Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
title_full | Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
title_fullStr | Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
title_full_unstemmed | Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
title_short | Cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
title_sort | cellulase recycling in high-solids enzymatic hydrolysis of pretreated empty fruit bunches |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6551891/ https://www.ncbi.nlm.nih.gov/pubmed/31178926 http://dx.doi.org/10.1186/s13068-019-1476-x |
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