Production of Hen Egg-White Lysozyme: Recombinant Expression in Pichia pastoris and Isolation of the Native Enzyme

Abstract

Hen egg-white lysozyme (HEWL) is a well-characterized antimicrobial enzyme widely used in the food industry, biotechnology, and biomedical research. The aim of this study was to investigate two approaches to lysozyme production: heterologous expression of its gene in Pichia pastoris and isolation of native HEWL from chicken egg white. For recombinant production, the pPICZαA-LysC-His construct was generated and methanol-induced expression was performed in P. pastoris GS115. Anti-His-reactive material was detected in induced T3 preparations and selected Ni-NTA fractions; however, selective enrichment of a protein with the expected molecular mass was not achieved, and the available data were therefore not considered definitive evidence for correctly processed recombinant rLysC. For the native approach, fresh chicken egg white was subjected to 30-kDa tangential-flow ultrafiltration followed by cation-exchange chromatography on SP Sepharose Fast Flow. Fractions eluted with 300 mM NaCl were enriched in a low-molecular-weight component with electrophoretic mobility corresponding to the HEWL region, and these preparations exhibited lytic activity in substrate zymography using Lactobacillus plantarum cell-wall material. These findings provide preliminary process-oriented observations on obtaining HEWL-enriched, lytically active preparations from fresh egg white. Evaluation of off-grade egg material remains a subject for future study.