초록
<P>Biotransformation of lignin to lipids is challenging due to lignin’s recalcitrant nature as a phenolic heteropolymer with a nonuniform structure that imparts rigidity and recalcitrance of plant cell walls. In this study, wild and engineered <I>Rhodococcus</I> strains (<I>R. opacus</I> PD630 and <I>R. jostii</I> RHA1 VanA<SUP>–</SUP>) with lignin degradation and/or lipid biosynthesis capacities were selected to establish fundamental understanding of the pathways and functional modules necessary to enable a platform for biological conversion of biomass-derived lignin to lipids. Degradation of lignin (39.6%, dry weight) was achieved by performing cofermentation with wild type <I>R. opacus</I> PD630 and engineered <I>R. jostii</I> RHA1 VanA<SUP>–</SUP>. Co-fermentation of these two strains produced higher lipids yield than single strain fermentation. Profiles of metabolites produced by the <I>Rhodococcus</I> strains while growing on alkali technical lignin suggested that lignin was depolymerized to reactive intermediates, such as vanillin, 2,3-dihydro-benzofuran, 2-methoxy-4-vinylphenol, and 3-hydroxy-4-methoxy-benzaldehyde, for lipid biosynthesis. Additionally, fatty acids (C13–C24), especially palmitic acid (C16:0; 35.8%) and oleic acid (C18:1; 47.9%), were accumulated in cells of <I>R. opacus</I> PD630 and <I>R. jostii</I> RHA1 VanA<SUP>–</SUP> with lignin as the sole carbon source. Results suggest that the cofermentation strategy can depolymerize lignin into aromatics and promote the lipid production. The lipids produced during cofermentation of lignin by <I>R. opacus</I> PD630 and <I>R. jostii</I> RHA1 VanA<SUP>–</SUP> showed promising potential in biofuel production.</P><P>A series of <I>Rhodococcus</I> strains were selected to enable a platform for bioconversion of alkali corn stover lignin to lipids.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ascecg/2017/ascecg.2017.5.issue-3/acssuschemeng.6b02627/production/images/medium/sc-2016-02627w_0011.gif'></P>