1 / 2022-06-04 19:17:40

Recombinant expression of hen egg white lysozyme with the assistance of a xylanase fusion partner in Pichia pastoris

Hen egg white lysozyme, Xylanase, Fusion protein, Pichia pastoris, High-density cultivation

Due to its bacteriolytic activity, hen egg white lysozyme (HEWL) is widely used in the feed, food, and pharmaceuticals industries. However, its application is hindered by low protein expression level in microbial expression systems. In this work, a novel fusion protein expression strategy was proposed for increasing the expression level of HEWL. Firstly, HEWL, fused with a high expressed fusion protein partner xylanase XynCDBFV, is expressed in Pichia pastoris. Secondly, a linker included endogenous proteases cleavage sites was introduced between two fusion proteins in order to separate them directly during the secretion process. Finally, the results show that the supernatant of XynCDBFV-HEWL have a higher HEWL expression level and activity compared with HEWL only. It should be noted that, the expression of HEWL reaches to about 3.5 g/L, and the activity of HEWL against Micrococcus lysodeikticus reaches to 1.50 × 10⁵ U/mL in a fed-batch fermentation, which is currently the highest level of recombinant expression of an egg white-derived lysozyme. Taken together, we acquired bioactive HEWL for large-scale recombinant production in Pichia pastoris by using the novel fusion protein expression strategy, which could then be used for a variety of applications.