Lactococcus lactis IL1403 harbors a putative sortase A (SrtA) and 11 putative sortase substrates that carry the canonical LPXTG signature of such substrates. We report here on the functionality of SrtA to anchor five LPXTG substrates to the cell wall, thus suggesting that SrtA is the housekeeping sortase in L. lactis IL1403.

No abstract

The possibility of accelerated cheese ripening through addition of liposome entrapped proteinase to milk was investigated. Both enzyme encapsulation rate in liposomes and their retention in cheese were evaluated with multilamellar vesicles (MLV) and reverse-phase evaporation vesicles (REV). Using REV in Saint-Paulin type curd, no nitrogen loss was observed to the whey due to the added enzymes in liposomes. In cheese, REV produced a more progressive proteolysis during ripening than MLV did. REV addition did not lead to texture defects. Bitterness development, a critical defect in enzyme added cheese, could be delayed and minimized using REV.

No abstract

A la dose de 450 Unités/l l'addition de Rulactine (métalloprotéase synthétisée par Microeoeeus easeolytieus) au lait servant à la fabrication de fromages à pâte pressée entraîne une intensification nette de la protéolyse et une modification de la texture de la pâte qui devient plus friable. On aboutit cependant à l'apparition d'amertume après 30 j d'affinage et à des pertes de rendement non négligeables au cours de la fabrication du caillé. Les diagrammes d'électrophorèse des caséines des fromages contenant une dose de 450 Unités montrent une dégradation plus intense de la caséine 13 et l'apparition nette d'une bande de faible mobilité électrophorétique. Cette bande caractéristique résulte de l'hydrolyse de la caséine 13. A la dose de 90 Unités/l de lait aucune différence n'a été observée entre les fromages essais et les témoins.Mots clés: Accélération de l'affinage -Fromages à pâte pressée -Protéolyse -Amertume -Texture -Protéase -Rulactine. Summary Use of Rulaetine as ripening agent in semi-hard eheeseAddition of 450 Units/l of Rulactine (metalloprotease from Mieroeoeeus caseolytieus) in milk used for serni-hard cheesemaking developed an intensification of the proteolysis and a modification of texture of the curd. Thus, curds with Rulactine were more crumbly than controls. With 450 Units/l of milk bitterness is occurring after 30 days of ripening and cheese yields were decreasing during cheesemaking. Electrophoregrams of curd-casein showed (for 450 Units dose) a significant increase of l3-casein breakdown and the presence of a new band with a low electrophoretic mobility. This specifie band results of J3-casein hydrolysis. At the level of 90 Units/l of milk no difference have been observed between the assay and the control cheeses.