Advanced Chemical Design for Efficient Lignin Bioconversion

Shangxian Xie, Qining Sun, Yunqiao Pu, Furong Lin, Su Sun, Xin Wang, Arthur J. Ragauskas, Joshua S. Yuan

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

Lignin depolymerization mainly involves redox reactions relying on the effective electron transfer. Even though electron mediators were previously used for delignification of paper pulp, no study has established a bioprocess to fragment and solubilize the lignin with an effective laccase-mediator system, in particular, for subsequent microbial bioconversion. Efficient lignin depolymerization was achieved by screening proper electron mediators with laccase to attain a nearly 6-fold increase of kraft lignin solubility compared to the control kraft lignin without laccase treatment. Chemical analysis suggested the release of a low molecular weight fraction of kraft lignin into the solution phase. Moreover, NMR analysis revealed that an efficient enzyme-mediator system can promote the lignin degradation. More importantly, the fundamental mechanisms guided the development of an efficient lignin bioconversion process, where solubilized lignin from laccase-HBT treatment served as a superior substrate for bioconversion by Rhodococcus opacus PD630. The cell growth was increased by 106 fold, and the lipid titer reached 1.02 g/L. Overall, the study has manifested that an efficient enzyme-mediator-microbial system can be exploited to establish a bioprocess to solubilize lignin, cleave lignin linkages, modify the structure, and produce substrates amenable to bioconversion.

Original languageEnglish
Pages (from-to)2215-2223
Number of pages9
JournalACS Sustainable Chemistry and Engineering
Volume5
Issue number3
DOIs
StatePublished - Mar 6 2017

Funding

The work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Bioenergy Technology Office (Grant No. DE-EE0006112) to J.S.Y. and A.J.R.. The research was also supportedby Texas A&M Agrilife Research's biofuel initiative to J.S.Y.

Keywords

  • Bioconversion
  • Laccase-mediatormicrobial
  • Lignin
  • Rhodococcus
  • Valorization

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