Genetically Decorating Microbial Surface Curli Fiber with Biocatalytic Properties

Genetically customized microbial surface represents an emerging strategy for creating effective and robust whole cell biocatalysts. In this study, we have genetically engineered new whole cell catalysts that utilize three functional modules: CsgA, SpyTag/SpyCatcher, and Mrcp19k. These modules can programmatically immobilize lipases onto the surface curli fibers of Escherichia coli. The genetically programmed E. coli surface curli fibers exhibited enhanced lipase enzyme dosage, specific activity, and resistance to harsh environments. The application of these genetically tailored whole cell catalysts in the synthesis of fatty acid methyl esters resulted in an 87% yield, with more than 80% relative activity retained after 5 consecutive batches. This genetically programmable immobilization strategy, particularly the integration of Mrcp19k, introduces a concept and technological platform that enables the creation of innovative and highly efficient whole cell biocatalysts and biotransformations.