Binding Peptide-Guided Immobilization of Lipases with Significantly Improved Catalytic Performance Using Escherichia coli BL21(DE3) Biofilms as a Platform

Developing novel immobilization methods to maximize the catalytic performance of enzymes has been a permanent pursuit of scientific researchers. Engineered Escherichia coli biofilms have attracted great concern as surface display platforms for enzyme immobilization. However, current biological conjugation methods, such as the SpyTag/SpyCatcher tagging pair, that immobilize enzymes onto E. coli biofilms seriously hamper enzymatic performance. Through phage display screening of lipase-binding peptides (LBPs) and co-expression of CsgB (nucleation protein of curli nanofibers) and LBP2-modified CsgA (CsgALBP2, major structural subunit of curli nanofibers) proteins, we developed E. coli BL21::ΔCsgA-CsgB-CsgALBP2 (LBP2-functionalized) biofilms as surface display platforms to maximize the catalytic performance of lipase (Lip181). After immobilization onto LBP2-functionalized biofilm materials, Lip181 showed increased thermostability, pH, and storage stability. Surprisingly, the relative activity of immobilized Lip181 increased from 8.43 to 11.33 U/mg through this immobilization strategy. Furthermore, the highest loading of lipase on LBP2-functionalized biofilm materials reached up to 27.90 mg/g of wet biofilm materials, equivalent to 210.49 mg/g of dry biofilm materials, revealing their potential as a surface with high enzyme loading capacity. Additionally, immobilized Lip181 was used to hydrolyze phthalic acid esters, and the hydrolysis rate against dibutyl phthalate was up to 100%. Thus, LBP2-mediated immobilization of lipases was demonstrated to be far more advantageous than the traditional SpyTag/SpyCatcher strategy in maximizing enzymatic performance, thereby providing a better alternative for enzyme immobilization onto E. coli biofilms.