The global challenges of environment protection, energy security, and economic development boost biofuel research throughout the world. Development of robust microbial catalysts to keep high productivity is crucial for economic biofuel production. Using the ethanologenic bacterium Zymomonas mobilis as a model, many systems biology studies have been carried out to unravel the inhibitor tolerance mechanism for robust strain development. In addition, a hydrocarbon-producing Z. mobilis has been constructed for advanced biofuel production. In this presentation, I will discuss our efforts to better understand the relationship between the productivity and the enhanced robustness obtained through mutagenesis and adaptation. Specifically, Next Generation Sequencing (NGS)-based genome resequencing was applied to investigate the genetic differences between Z. mobilis parental strain 8b and robust strains developed through mutagenesis and lab-directed adaptive evolution. Farnesene-producing plasmids were further introduced into four of these mutants. Shake flask studies and controlled fermentation were performed to investigate the farnesene production in pretreated cornstover hydrolysate liquor (CL) and saccharified slurries from both pretreated cornstover (CS) and deacetylated pretreated cornstover (DCS). In addition, transcriptomics of NGS-based strand specific RNA-Seq (ssRNA-Seq) was applied to understand robustness against toxic slurries and farnesene productivity of Z. mobilis. The result suggests the impact of toxic slurries has more dramatic influence on Z. mobilis transcriptional profile than that of genetic change, and the transferability of certain genetic loci conferring enhanced robustness for productivity improvement especially when the production condition is similar to the condition used for robustness selection.

Robustness and productivity: lessons from metabolic engineering and RNA-Seq studies in Zymomonas mobilis

249th National Meeting (2015)

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Robustness and productivity: lessons from metabolic engineering and RNA-Seq studies in Zymomonas mobilis<br />