(643a) Transcriptional Regulators for Predictable and Precise Gene Expression in the Metabolically Versatile Rhodopseudomonas Palustris CGA009

Non-model microorganisms’ unique metabolic processes and resilience in stress conditions make them appealing biotechnology chassis; yet, the engineering tools for these promising hosts can be limited. The purple non-sulfur bacterium Rhodopseudomonas palustris CGA009 adapts to an immense range of environmental conditions through four metabolic modes; photoautotrophic, photoheterotrophic, chemoautotrophic, and chemoheterotrophic. It can fix carbon dioxide and nitrogen or break down organic compounds for its carbon and nitrogen requirements while using light, inorganic, or organic compounds for its source of energy. R. palustris can also remain metabolically active in a non-growing state for months. This versatile bacterium has both aerobic and anaerobic pathways for degrading aromatic compounds, including many monolignols. To explore the regulation of R. palustris’ different metabolic modes and to take advantage of the purple non-sulfur bacterium’s biochemical processing potential to convert waste products, such as depolymerized lignin and carbon dioxide, into value-added products, tools for predictable, synthetic gene regulation need to be constructed. Similar to many non-model microorganisms, a synthetic biology toolbox for R. palustris does not currently exist. To begin addressing this limitation, a family of orthogonal, inducible promoters is being developed and the bacterium’s intrinsic antibiotic resistance characterized to enable the precise control of gene expression. This work will significantly expand the available heterologous transcriptional regulators beyond the single constitutive promoter that has been employed in this promising microbe to date, while the characterization of antibiotic resistance will improve the predictability of gene expression from autonomously replicating plasmids. This research starts to build the foundation from which R. palustris can be developed as a biotechnology platform.