Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis
Abstract Background Wheat straw, the most abundant lignocellulosic biomass in China, is rich in cellulose that can be hydrolyzed and then converted into biofuels, such as bioethanol and biohydrogen. However, the accessibility of cellulose and the enzyme activity are greatly reduced in the presence o...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2019-06-01
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| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13068-019-1499-3 |
| _version_ | 1811338001828020224 |
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| author | Zhichao Deng Ao Xia Qiang Liao Xianqing Zhu Yun Huang Qian Fu |
| author_facet | Zhichao Deng Ao Xia Qiang Liao Xianqing Zhu Yun Huang Qian Fu |
| author_sort | Zhichao Deng |
| collection | DOAJ |
| description | Abstract Background Wheat straw, the most abundant lignocellulosic biomass in China, is rich in cellulose that can be hydrolyzed and then converted into biofuels, such as bioethanol and biohydrogen. However, the accessibility of cellulose and the enzyme activity are greatly reduced in the presence of lignin. This significantly increases the enzyme cost in the saccharification, which hampers industrial production of lignocellulosic biofuels. In this study, a laccase treatment system mediated by 1-hydroxybenzotriazole was employed to modify and degrade lignin to enhance subsequent enzymatic saccharification of wheat straw. A kinetic model considering enzyme adsorption on lignin was proposed to estimate the saccharification performance. Results Fourier transform infrared spectroscopy (FTIR) analyses showed that the peak intensity of lignin structure characteristics significantly changed after laccase-mediated system (LMS) treatment. 2D-nuclear magnetic resonance (NMR) analyses indicated that the aromatic ether bonds were cleaved and that guaiacyl (G) was oxidized after LMS treatment. X-ray diffraction (XRD) analyses suggested that the crystallinity of lignocellulose increased due to the partial degradation of lignin. As a result, the nonproductive adsorption of the enzyme on lignin was reduced by 28%, while the reducing sugar yield increased by 26%. A semi-empirical kinetic model was used to estimate the reducing sugar yield, the initial hydrolysis rate (K M ) and deactivation rate coefficient (α) of LMS-pretreated wheat straw were 0.157 (h−1) and 0.214 (h−1), respectively. The model showed high accuracy (predicting error < 10%) for describing the behavior of laccase-treated wheat straw hydrolysis when the solid loading is < 5%. Conclusions The adsorption ability of the enzyme to lignin was reduced after LMS pretreatment. Physicochemical analyses showed that the chemical groups of lignin and lignocellulose were changed, with the crystallinity of the lignocellulose increasing after LMS treatment. A semi-empirical kinetic model was proposed to estimate the reducing sugar yield, which showed high accuracy for predicting the hydrolysis performance of laccase-treated wheat straw. |
| first_indexed | 2024-04-13T18:04:24Z |
| format | Article |
| id | doaj.art-348c3f3284c74e218dc28e2099a8f864 |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-04-13T18:04:24Z |
| publishDate | 2019-06-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-348c3f3284c74e218dc28e2099a8f8642022-12-22T02:36:07ZengBMCBiotechnology for Biofuels1754-68342019-06-0112111210.1186/s13068-019-1499-3Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysisZhichao Deng0Ao Xia1Qiang Liao2Xianqing Zhu3Yun Huang4Qian Fu5Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of EducationKey Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of EducationKey Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of EducationKey Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of EducationKey Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of EducationKey Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of EducationAbstract Background Wheat straw, the most abundant lignocellulosic biomass in China, is rich in cellulose that can be hydrolyzed and then converted into biofuels, such as bioethanol and biohydrogen. However, the accessibility of cellulose and the enzyme activity are greatly reduced in the presence of lignin. This significantly increases the enzyme cost in the saccharification, which hampers industrial production of lignocellulosic biofuels. In this study, a laccase treatment system mediated by 1-hydroxybenzotriazole was employed to modify and degrade lignin to enhance subsequent enzymatic saccharification of wheat straw. A kinetic model considering enzyme adsorption on lignin was proposed to estimate the saccharification performance. Results Fourier transform infrared spectroscopy (FTIR) analyses showed that the peak intensity of lignin structure characteristics significantly changed after laccase-mediated system (LMS) treatment. 2D-nuclear magnetic resonance (NMR) analyses indicated that the aromatic ether bonds were cleaved and that guaiacyl (G) was oxidized after LMS treatment. X-ray diffraction (XRD) analyses suggested that the crystallinity of lignocellulose increased due to the partial degradation of lignin. As a result, the nonproductive adsorption of the enzyme on lignin was reduced by 28%, while the reducing sugar yield increased by 26%. A semi-empirical kinetic model was used to estimate the reducing sugar yield, the initial hydrolysis rate (K M ) and deactivation rate coefficient (α) of LMS-pretreated wheat straw were 0.157 (h−1) and 0.214 (h−1), respectively. The model showed high accuracy (predicting error < 10%) for describing the behavior of laccase-treated wheat straw hydrolysis when the solid loading is < 5%. Conclusions The adsorption ability of the enzyme to lignin was reduced after LMS pretreatment. Physicochemical analyses showed that the chemical groups of lignin and lignocellulose were changed, with the crystallinity of the lignocellulose increasing after LMS treatment. A semi-empirical kinetic model was proposed to estimate the reducing sugar yield, which showed high accuracy for predicting the hydrolysis performance of laccase-treated wheat straw.http://link.springer.com/article/10.1186/s13068-019-1499-3LignocelluloseLaccase treatmentKinetic modelSaccharificationWheat straw |
| spellingShingle | Zhichao Deng Ao Xia Qiang Liao Xianqing Zhu Yun Huang Qian Fu Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis Biotechnology for Biofuels Lignocellulose Laccase treatment Kinetic model Saccharification Wheat straw |
| title | Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis |
| title_full | Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis |
| title_fullStr | Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis |
| title_full_unstemmed | Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis |
| title_short | Laccase pretreatment of wheat straw: effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis |
| title_sort | laccase pretreatment of wheat straw effects of the physicochemical characteristics and the kinetics of enzymatic hydrolysis |
| topic | Lignocellulose Laccase treatment Kinetic model Saccharification Wheat straw |
| url | http://link.springer.com/article/10.1186/s13068-019-1499-3 |
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