(54b) Expanding the Engineered Modular Ester Fermentative Pathways in Escherichia coli

Acid production is a major (by)product in chemical production as well as fermentative metabolism.  These products are sometimes desired, but are often times undesired.  These metabolically undesired products are considered waste carbon the cells do not use for directed formation of the desired product.  Here, we establish a systematic approach to utilize waste acids to be anaerobically converted into useful ester molecules via our previously established Escherichia coli modular cell platform.  The fermentative pathways are designed to convert acids to their respective ac(et)yl-CoAs and produce ethanol as precursor molecules.  The ac(et)yl-CoAs and ethanol are then condensed by a library of alcohol ac(et)yl transferases (AATs) to i) demonstrate expansion of the unique fermentative ester library and ii) facilitate a comparative analysis of sequence/structure to function of AATs.  We demonstrate the anaerobic fermentation from glucose and acids for directed production of various unique ethyl esters.  This work expands anaerobic fermentative ester production for the use in flavorings, fragrances, and solvents, as well as provides comparative insights into a sample library of AATs.