(253d) Lignin Degradation Mechanisms of Rhodopseudomonas Palustris CGA009

Lignin is a complex and abundant biopolymer that constitutes a significant proportion of the structural material of many plants. However, due to its lack of useful chemistry and recalcitrance as a carbon feedstock for microorganisms, it is commonly treated as waste in industries where it is a byproduct, such as in paper manufacturing and ethanol production from corn stover hydrolysate. Lignin requires complex biochemistry for its degradation, which is typically supplied from a community of microorganisms and fungi, as a result, an overwhelming majority of annually produced lignin is instead burned as fuel. With the pollutants and non-degradable products from abiotic chemical synthesis having an ever more pronounced effect on the environment, there remains a large potential for lignin to be valorized into more useful chemicals which these abiotic processes manufacture. Rhodopsuedomonas palustris (R. palustris), a non-model, gram-negative soil bacterium with a wide array of unique metabolic features, has demonstrated its ability to catabolize many lignin monomers, and with its unique biochemistry that allows it to produce many sought-after chemicals such as bioplastic and biofuels, it has the potential to become a metabolic engineering chassis. From analysis of growth data collected in this study, R. palustris is able to aerobically and anaerobically catabolize multiple lignin breakdown products (LBPs), including p-coumarate, sodium ferulate, p-coumaryl, coniferyl, and sinapyl alcohols. In this study, we investigate the lignin catabolic pathways of R. palustris through a “multi-omics” perspective by combining both proteomic and transcriptomic profiles of R. palustris cultured with several LBPs. Through initial analysis of transcriptomic data, potential pathways for the aerobic catabolism of each LBP have been identified, while anaerobically, p-coumarate appears to be upregulated in all cases. This study will advance the understanding of the complex carbon metabolism of R. palustris, and assist in enabling sustainable biochemical production.

Brown, B., Wilkins, M., & Saha, R. (2022). Rhodopseudomonas palustris: A biotechnology chassis. In Biotechnology Advances (Vol. 60). Elsevier Inc. https://doi.org/10.1016/j.biotechadv.2022.108001

Immethun, C. M., Kathol, M., Changa, T., & Saha, R. (2022). Synthetic Biology Tool Development Advances Predictable Gene Expression in the Metabolically Versatile Soil Bacterium Rhodopseudomonas palustris. Frontiers in Bioengineering and Biotechnology, 10. https://doi.org/10.3389/fbioe.2022.800734

Morris, D. S., Chowdhury, N. B., Kathol, M., & Saha, R. (2023). Opening the door to nitrogen fixation in oxygenic phototrophs. In Trends in Biotechnology (Vol. 41, Issue 3, pp. 283–285). Elsevier Ltd. https://doi.org/10.1016/j.tibtech.2023.01.005