(544d) Enabling Bioconversion of Biorefinery Wastes to Lipids with Oleaginous Rhodococci

Conversion of cellulosic ethanol biorefinery wastes, which contain mainly lignin and some carbohydrates, to value-added bioproducts will greatly increase the competiveness of biomass refinery. Wild and engineered Rhodococcus strains (R. opacus PD630, R. jostii RHA1 and R. jostii RHA1 VanA^-) with lignin degradation and/or lipid biosynthesis capacities were used to co-ferment lignin in order to establish a fundamental understanding of the pathways and functional modules necessary to enable a platform for biological conversion of biomass-derived lignin to lipids. In this study, genomics, transcriptomics, and proteomics analysis were carried out to help identify catabolic pathways in co-fermentation for funneling biosynthesis of TAGs from both of lignin and carboxylates. About 50% of loaded lignin was converted by the microbes. Some intermediates (e.g. vanillin, vanillic acid, and benzoic acid) that could further form acetyl-CoA for lipid production were detected in the co-fermentation broths. In addition, NMR analysis indicated that monomers derived from lignin depolymerization could be instantly consumed by these strains as carbon sources to accumulate lipids. Accumulation of fatty acids (C14-C18) in cells, especially palmitic acid (C16:0, 35.8%) and oleic acid (C18:1, 47.9%), was detected. In addition, systems biology approach revealed the carbon utilization pattern from both lignin and carbohydrates in unique coordinative pathways during co-fermentation.