4-Hydroxy-6-methyl-2-pyrone, also referred to as triacetic acid lactone (TAL), is a signature byproduct of many polyketide synthases, resulting from offloading of the corresponding unreduced triketide. TAL is a precursor to a wide variety of commodity and higher-value chemicals1,2 and TAL biosynthesis therefore represents renewable production of a platform chemical. In a previous study by our group, an endogenous TAL sensor-reporter system was developed by engineering the Escherichia coli regulatory protein AraC to activate gene expression in response to TAL. The reporter was applied in a high-throughput screen to evolve Gerbera hybrida 2-pyrone synthase (2-PS) for improved TAL production when expressed in E. coli 3. In this work we continue to improve TAL production in E. coli by creating and screening host strain genomic libraries through random transposon insertions. We will describe individual and combined genetic modifications leading to our highest TAL-producing strain. Our results further demonstrate the applicability of engineered AraC variants as customized endogenous molecular reporters for high-throughput screening to engineer biocatalysis. 1. Xie, D.; Shao, Z.; Achkar, J.; Zha, W.; Frost, J. W.; Zhao, H., Microbial synthesis of triacetic acid lactone. Biotechnol. Bioeng. 2006, 93 (4), 727-736. 2. Chia, M.; Schwartz, T. J.; Shanks, B. H.; Dumesic, J. A., Triacetic acid lactone as a potential biorenewable platform chemical. Green Chem. 2012, 14 (7), 1850-1853. 3. Tang, S.-Y.; Qian, S.; Akinterinwa, O.; Frei, C. S.; Gredell, J. A.; Cirino, P. C., Screening for enhanced triacetic acid lactone (TAL) production by recombinant Escherichia coli expressing a designed TAL reporter. J. Am. Chem. Soc. 2013, 135 (27), 10099-10103.

Engineering recombinant Escherichia coli for improved triacetic acid lactone production by screening transposon insertion libraries

249th National Meeting (2015)

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