Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls
<p>Abstract</p> <p>Background</p> <p>Lignin is an integral component of the plant cell wall matrix but impedes the conversion of biomass into biofuels. The plasticity of lignin biosynthesis should permit the inclusion of new compatible phenolic monomers such as flavonoi...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2012-08-01
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| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://www.biotechnologyforbiofuels.com/content/5/1/59 |
| _version_ | 1818540076102057984 |
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| author | Elumalai Sasikumar Tobimatsu Yuki Grabber John H Pan Xuejun Ralph John |
| author_facet | Elumalai Sasikumar Tobimatsu Yuki Grabber John H Pan Xuejun Ralph John |
| author_sort | Elumalai Sasikumar |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Lignin is an integral component of the plant cell wall matrix but impedes the conversion of biomass into biofuels. The plasticity of lignin biosynthesis should permit the inclusion of new compatible phenolic monomers such as flavonoids into cell wall lignins that are consequently less recalcitrant to biomass processing. In the present study, epigallocatechin gallate (EGCG) was evaluated as a potential lignin bioengineering target for rendering biomass more amenable to processing for biofuel production.</p> <p>Results</p> <p><it>In vitro</it> peroxidase-catalyzed polymerization experiments revealed that both gallate and pyrogallyl (B-ring) moieties in EGCG underwent radical cross-coupling with monolignols mainly by β–O–4-type cross-coupling, producing benzodioxane units following rearomatization reactions. Biomimetic lignification of maize cell walls with a 3:1 molar ratio of monolignols and EGCG permitted extensive alkaline delignification of cell walls (72 to 92%) that far exceeded that for lignified controls (44 to 62%). Alkali-insoluble residues from EGCG-lignified walls yielded up to 34% more glucose and total sugars following enzymatic saccharification than lignified controls.</p> <p>Conclusions</p> <p>It was found that EGCG readily copolymerized with monolignols to become integrally cross-coupled into cell wall lignins, where it greatly enhanced alkaline delignification and subsequent enzymatic saccharification. Improved delignification may be attributed to internal trapping of quinone-methide intermediates to prevent benzyl ether cross-linking of lignin to structural polysaccharides during lignification, and to the cleavage of ester intra-unit linkages within EGCG during pretreatment. Overall, our results suggest that apoplastic deposition of EGCG for incorporation into lignin would be a promising plant genetic engineering target for improving the delignification and saccharification of biomass crops.</p> |
| first_indexed | 2024-12-11T21:50:35Z |
| format | Article |
| id | doaj.art-de9e2ed55f43463ebc7f6474d18bfd4f |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-12-11T21:50:35Z |
| publishDate | 2012-08-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-de9e2ed55f43463ebc7f6474d18bfd4f2022-12-22T00:49:28ZengBMCBiotechnology for Biofuels1754-68342012-08-01515910.1186/1754-6834-5-59Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell wallsElumalai SasikumarTobimatsu YukiGrabber John HPan XuejunRalph John<p>Abstract</p> <p>Background</p> <p>Lignin is an integral component of the plant cell wall matrix but impedes the conversion of biomass into biofuels. The plasticity of lignin biosynthesis should permit the inclusion of new compatible phenolic monomers such as flavonoids into cell wall lignins that are consequently less recalcitrant to biomass processing. In the present study, epigallocatechin gallate (EGCG) was evaluated as a potential lignin bioengineering target for rendering biomass more amenable to processing for biofuel production.</p> <p>Results</p> <p><it>In vitro</it> peroxidase-catalyzed polymerization experiments revealed that both gallate and pyrogallyl (B-ring) moieties in EGCG underwent radical cross-coupling with monolignols mainly by β–O–4-type cross-coupling, producing benzodioxane units following rearomatization reactions. Biomimetic lignification of maize cell walls with a 3:1 molar ratio of monolignols and EGCG permitted extensive alkaline delignification of cell walls (72 to 92%) that far exceeded that for lignified controls (44 to 62%). Alkali-insoluble residues from EGCG-lignified walls yielded up to 34% more glucose and total sugars following enzymatic saccharification than lignified controls.</p> <p>Conclusions</p> <p>It was found that EGCG readily copolymerized with monolignols to become integrally cross-coupled into cell wall lignins, where it greatly enhanced alkaline delignification and subsequent enzymatic saccharification. Improved delignification may be attributed to internal trapping of quinone-methide intermediates to prevent benzyl ether cross-linking of lignin to structural polysaccharides during lignification, and to the cleavage of ester intra-unit linkages within EGCG during pretreatment. Overall, our results suggest that apoplastic deposition of EGCG for incorporation into lignin would be a promising plant genetic engineering target for improving the delignification and saccharification of biomass crops.</p>http://www.biotechnologyforbiofuels.com/content/5/1/59LignificationRadical cross-couplingDigestibilityPretreatmentSaccharification |
| spellingShingle | Elumalai Sasikumar Tobimatsu Yuki Grabber John H Pan Xuejun Ralph John Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls Biotechnology for Biofuels Lignification Radical cross-coupling Digestibility Pretreatment Saccharification |
| title | Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls |
| title_full | Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls |
| title_fullStr | Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls |
| title_full_unstemmed | Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls |
| title_short | Epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls |
| title_sort | epigallocatechin gallate incorporation into lignin enhances the alkaline delignification and enzymatic saccharification of cell walls |
| topic | Lignification Radical cross-coupling Digestibility Pretreatment Saccharification |
| url | http://www.biotechnologyforbiofuels.com/content/5/1/59 |
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