In Nature, fungi and bacteria are able to deconstruct lignin, cellulose, and hemicellulose, uptake their principal constituents, and utilize these molecules as carbon and energy sources. In this work, we screened a wide range of bacteria for growth on alkaline pretreated liquor (APL) from corn stover (a lignin-enriched, process relevant substrate), to examine natural mechanisms of lignin depolymerization, catabolism, and intracellular carbon storage. Specifically, we analyzed the secretion of ligninolytic enzymes (laccases and peroxidases) as a function of treatment time and the total content and molecular weight distribution of lignin at the end of the incubations. In addition, we monitored the consumption of more than 20 aromatics, by advanced techniques as GCxGC/TOF-MS, and other carbon sources from APL, such as sugars and organic acids. In parallel, we studied the intracellular accumulation of storage compounds such as polyhydroxyalkanoates and fatty acids by through flow cytometry, microscopy, and GC-MS. The results demonstrated simultaneous lignin depolymerization, aromatic consumption, and intracellular production of value-added compounds, which provides a step toward to an integrated approach to selectively upgrade an enriched-lignin substrate by using a single biological catalyst. Overall, understanding the features and capabilities of these native bacteria for multiple functions simultaneously inform rational approaches to design enhanced microbes with improved function towards the ultimate aim of producing third-generation, renewable hydrocarbon fuels and value-added chemicals.

From lignin depolymerization to coproduct generation by using a single bacterial catalyst

249th National Meeting (2015)

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