Production of Lactobacilli Proteinases for the Manufacture of Bioactive Peptides: Part II—Downstream Processes

Cell‐envelope proteinases from lactic acid bacteria: Biochemical features and biotechnological applications

“…Chaotropic agents increase the solubility of the proteins by transferring nonpolar groups to water by chaotropic ions (Hatefi & Hanstein, 1969). On the other hand, the noncovalent interactions between bacterial surfaces and surface proteins can also be interfered by chaotropic agents, resulting in the release of cell surface–bound proteins and enzymes (Agyei et al., 2013).…”

“…Urea has good protein denaturation properties through its ability to disrupt noncovalent (hydrogen) bonds. Thus, urea interacts with polar moieties of proteins by hydrogen bonding, and this disrupts intramolecular hydrogen bonding within the CEP proteins (Agyei et al., 2013; Bennion & Daggett, 2003). Apart from binding to protein, urea can also alter solvent mechanism by affecting the structure and bonding behavior of water molecules in the vicinity (Bennion & Daggett, 2003).…”

“…The effective concentration of SDS for CEP extraction is between 0.1% and 2% (v/v) (Bhowmik et al., 1985; Chagnaud et al., 1992; Schär‐Zammaretti & Ubbink, 2003). Triton X‐100 and Tween 80 are not effective agents on their own, and are therefore often used as additives in mixed enzyme extraction agents (Agyei et al., 2013; Bhowmik et al., 1985).…”

“…The extraction of cell wall–associated proteinase can be done using lysozyme and mutanolysin that can hydrolyze the peptidoglycan layer of cell wall. However, this approach is more likely to lead to cell lysis, releasing intracellular and transmembrane cell proteins (Agyei et al., 2013), but it has been shown as useful in the extraction of some CEPs. For example, Atlan, Laloi, and Portalier (1990) combined lysozyme and mutanolysin with cold temperature shock and extracted excellent amount of cell wall–associated proteinases from Lb.…”

“…Most LAB rely on the hydrolytic products of the proteolytic system to meet their nitrogen requirements because LAB are auxotrophic for several amino acids (Turbay, de Giori, & Hebert, 2009), and the usual growth medium, milk, is deficient in free amino acids (Juillard, Lopez‐Kleine, & Monnet, 2021). CEPs are also referred to as cell wall–bound proteinases, cell envelope–bound proteinases, cell‐surface proteinases, cell envelope–associated proteinases, or lactocepins (see Figure 1) (Agyei, Potumarthi, & Danquah, 2013). During milk fermentation, CEPs are reported to allow the growth of LAB in milk by hydrolyzing caseins to peptides and amino acids (Sadat‐Mekmene, Genay, Atlan, Lortal, & Gagnaire, 2011).…”