Immobilization and Stabilization of an Engineered Acyltransferase for the Continuous Biosynthesis of Simvastatin in Packed-Bed Reactors

Simvastatin is a top-selling cholesterol-lowering drug traditionally obtained through a semi-synthetic process starting from lovastatin. However, this process is cost-demanding and makes use of chemical reagents that can generate considerable waste. The sustainability concerns underlying the current semi synthetic process encouraged us to immobilize the engineered acyltransferase LovD-BuCh2 on different pore carriers to develop an innovative and sustainable process for the continuous biomanufacturing of simvastatin. We systematically assessed the effect of the immobilization on the functional and structural properties of the immobilized enzyme, the enzyme spatial distribution across the solid material, and the thermal stability of the immobilized biocatalysts. After screening several immobilization carriers, we selected LovD-BuCh2 immobilized on the controlled porous glass particles functionalized with Fe3+- catechol complexes as the most suitable heterogeneous biocatalyst to optimize the continuous synthesis of simvastatin. This immobilized enzyme was four times more thermally stable than its free counterpart and maintained > 60% product yield during five operational cycles in the batch. Under the optimal flow conditions, we achieved 100% of simvastatin yield with a space-time yield of 4.61 g L-1 h(-1) and a specific productivity of 17 mg(product) x mg(enzyme)(-1) L-1. This flow-biocatalysis system improves some green chemistry metrics such as the reaction mass efficiency and the atom economy when compared to previous studies of simvastatin manufacturing.