S130: Understanding and mitigating carboxylic acid toxicity in Escherichia coli and Saccharomyces cerevisiae

Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for drop-in replacements of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, including Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired product titer.

We will discuss our recent findings regarding toxicity of hexanoic, octanoic and decanoic acids in E. coli and S. cerevisiae. In both organisms the cell membrane is targeted by these compounds, though the specifics of the damage and the resulting organism responses differ. Membrane damage and organism response is quantified in terms of membrane fluidity, integrity, composition and hydrophobicity. In E. coli we confirm that toxicity effects imposed by exogenous supplementation are also observed in carboxylic acid-producing strains. Metabolic engineering strategies to increase the membrane resilience to these compounds are also discussed.