Cell surface localization and function of the cell envelope proteinase derived from the lactic acid bacteria strains

Lactic acid bacteria (LAB) are renowned for their proteolytic systems, particularly cell envelope proteinases (CEPs), which hydrolyze caseins into peptides and amino acids essential for bacterial growth, flavor development, and bioactive peptide production. The protein hydrolysis system of LAB comprises cell envelope proteinases (CEPs), oligopeptide transport systems, and intracellular peptidases. Among them, CEP is pivotal, facilitating casein degradation to enhance flavor and texture in fermented products while releasing bioactive peptides through enzymatic hydrolysis. Additionally, CEP contributes significantly to bacterial physiological functions and interactions with the host Gastrointestinal tract. This review provides an updated synthesis of CEP biosynthesis, maturation, and regulation, highlighting novel insights into strain-specific CEP diversity and omics-driven elucidation of CEP-host interactions. Unique regulatory mechanisms governing CEP expression in mixed cultures, such as CodY repression in <i>Lactococcus</i> and two-component systems in <i>Lactobacillus</i>, as well as targeted genetic engineering strategies to enhance the release of customized peptides. Furthermore, we emphasize the underexplored health applications of CEP-derived bioactive peptides, while critically addressing challenges in peptide stability and bioavailability. By integrating structural-functional relationships, metabolic implications, and translational hurdles, it aims to guide future research toward industrial and clinical exploitation of CEPs for functional food innovation and therapeutic development.