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Identification of Succinic Acid Tolerance Genes in E.Coli

Amarjeet Singh, Chemical & Biological Engineering, University of Colorado at Boulder, 1111 Engineering Drive, Campus Box 424, Boulder, CO 80309 and Ryan T. Gill, Department of Chemical and Biological Engineering, University of Colorado, ECCH 111 Campus Box 424, Boulder, CO 80309.

Succinic acid (SA) has been identified as an important target chemical for biorefining efforts. Various engineered E.coli strains have been constructed to produce succinic acid as a major fermentation product., However, product toxicity is one of the primary concerns as bacterial growth inhibition by SA determines final titer and productivity of the fermentation process. We aim improve SA tolerance in E.coli. Our lab has developed a plasmid library based genome-wide technique, Sequential Chip Analysis of Library Enrichment (SCALEs), that can be used to identify genes whose over-expression would confer a specific phenotype. Using this technique .we identified genes involved in metabolite transport, amino acid metabolism, DNA repair, and citrate metabolism among others that can lead to an increased tolerance towards SA. The nature of the genes selected by SCALES also appears to depend upon the selection strategy employed (growth in batch mode or in continuous mode).