Characterization of Cell-Envelope Proteinases from Two Lacticaseibacillus casei Strains Isolated from Parmigiano Reggiano Cheese
Department of Life Sciences, University of Modena and Reggio Emilia, via Amendola, 2—Pad. Besta, 42100 Reggio Emilia, Italy
Department of Agriculture, Food and Environment, University of Catania, via Santa Sofia, 100, 95123 Catania, Italy
ProBioEtna srl, Spin off University of Catania, via Santa Sofia, 100, 95123 Catania, Italy
Author to whom correspondence should be addressed.
Academic Editor: Rosa Siciliano
Received: 9 November 2021
Revised: 12 January 2022
Accepted: 12 January 2022
Published: 14 January 2022
Lactic acid bacteria are nutritionally fastidious microorganisms typically used in the production of fermented dairy foods. The lactic acid bacteria’s proteolytic system is crucial for their growth in milk, and plays a paramount role in developing the organoleptic and healthy properties of fermented dairy foods. Cell-envelope proteinases are the first component of this system, responsible for the degradation of caseins into short peptides. In the present work, the cell-envelope proteinases of two highly proteolytic Lacticaseibacillus casei strains, previously isolated from ripened Parmigiano Reggiano cheese, were characterized from a genetic and biochemical point of view. Two different prt genes existed in the genomes of both strains, but only one, named prtR1, was expressed. PrtR1 proteins extracted from both strains displayed the highest activity at 40 °C and pH 7. Interestingly, PrtR1 extracted from Lacticaseibacillus casei PRA205 retained some residual activity at 5 °C and at pH 4. These important biotechnological features can be exploited in the production of fermented dairy products. Peptidomic analysis revealed that both proteinases were able to release β- and αS1-casein-derived bioactive peptides, suggesting that Lacticaseibacillus casei can be a source of new proteinases that can be exploited for the formulation of dairy beverages or hydrolysates enriched in bioactive peptides.