Developing novel methods to investigate the basis of solvent toxicity in bacteria

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Eugene Fletcher, Chris E. French

University of Edinburgh, United Kingdom

Toxicity of organic solvents to microbial hosts is a major consideration in the economical production of biofuels such as ethanol and especially butanol, with low product concentrations leading to high recovery costs. Understanding the mechanisms involved in solvent tolerance is crucial for rationally engineering robust microbes. We have developed a bioluminescence assay to determine the effects of different genes on survival in four model inhibitors-ethanol, n-butanol, acetone and furfural. Adopting a synthetic biology approach, a library of potential solvent tolerance BioBricks (genes) was generated and tested as proof-of-concept. Using this method, we have generated a set of tolerance modules suited for these inhibitory compounds, which can then be combined with genetic modules encoding substrate breakdown and product formation pathways. Ultimately, we hope to generate improved biofuel-producing systems which can generate higher product concentrations, greatly improving process economics. A similar approach can be used to model interactions between different genes which give rise to other complex phenotypes.