Microbial whole-cell biocatalysts perform a series of biochemical reactions to produce useful chemicals from renewable feedstocks. To optimize the target chemical production, metabolic engineering often involves overexpression of multiple enzymes of the desirable production pathway that requires multiple levels of optimization such as gene expression, enzyme solubility, metabolic burden, and metabolite toxicity. Such an optimization is not an trivial engineering problem. To tackle this, we employ the âlabor divisionâ strategy by modularly engineering a synthetic microbial consortium for efficient biosynthesis of designer bioesters as a case study. Through characterization of single and co-cultures, we not only demonstrated enhanced ester production by synthetic microbial co-culture systems but also elucidated metabolic bottlenecks encountered by a single-species fermentation.