Session: Recent Advancements in Lignin Valorization Strategies for Fuels and Chemicals:

Lignin is an abundant biopolymer that provides structural support to plant cell walls and serves as a potential feedstock for the production of biofuels and value-added chemicals. However, biological conversion of lignin into valuable products is yet to be fully explored. Drupe endocarp biomass such as peach pits, walnut and almond shells have high lignin content and arise as agricultural wastes with no commercial value. Antioxidant compounds, such as carotenoids, have wide applications towards food, pharmaceutical and agricultural industry and can be produced naturally by microbes.
This study explores the valorization of lignin derived from lignin-rich endocarp biomass through fermentation. The objective of this study was to fractionate lignin from fruit endocarps to be utilized as carbon source for carotenoid-producing microorganism. Lignin was extracted from both walnut and peach endocarps using two pretreatment methods- alkaline and deep eutectic solvents (DES). The lignin streams were characterized by using gel permeation chromatography (GPC) to analyze molecular weight distribution and Fourier transform infrared spectroscopy (FTIR) and 2D HSQC NMR for structural and compositional analyses. The astaxanthin-producing fungal strains were cultivated using endocarp derived lignin as sole carbon source with supplemented nitrogen source. Astaxanthin was extracted and analyzed using high-performance liquid chromatography (HPLC). The coproduction of high-value products will provide a sustainable solution to agricultural waste and improve the economic efficiency of biomass feedstock conversion to fuels and chemicals. Developing renewable carotenoids is also a great addition to the fast-growing natural antioxidant market demand.

Jian Shi

University of Kentucky

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