Autolysis and intracellular enzyme release from cheese related dairy lactobacilli

The abiIity of Lactobacillus helveticus, Lb. delbrueckii subsp. bulgaricus, Lb. delbrueckii subsp. lactis, Lb. casei, Lb. plantarum, Lb. fermentum and Lb. brevis to lyse under various conditions of temperature, sodium chloride concentration and pH was investigated. Intracellular enzymes released from the cells in vitro and in a cheese system were also considered. A temperature close to the optimun temperature for growth, a pH varying from 5.5 to 6.5 and a sodium chloride concentration varying from 0.5 to 1.0 M as weil as a freezing and thawing treatment seem to be the optimal conditions for cell autolysis. Enzymes release in vitro and in the cheese were found to be related to the rate of autolysis of the cells. InralElsevier, Paris autolysis / Lactobacillus / aminopeptidase / ripening / cheese Rsum -Autolyse et relargage des enzymes intracellulaires des lactobacilles apparents au fromage. L'autolyse des bactries Lactobacillus helveticus, Lb. delbrueckii subsp. bulgaricus, Lb. delbrueckii subsp. lactis, Lb. casei, Lb. plantarum, Lb. fermentum et Lb. brevis a t tudie dans des conditions diffrentes de temprature, pH, et concentration en chlorure de sodium. Le relargage des activits enzymatiques in vitro et dans un fromage modle a aussi t pris en considration. Les rsultats obtenus montrent qu'une temprature proche de la temprature optimale de croissance de la bactrie, un pH variant de 5,5 6,5 selon les souches, ainsi qu'un traitement de conglation/dconglation sembleraient tre les conditions optimales pour l'autolyse des cellules de Lactobacillus tudies. Il a aussi t dmontr que les souches montrant une forte autolyse rel arguent leurs enzymes intracellulaires plus rapidement dans le caill. InralElsevier, Paris autolyse / Lactobacillus / aminopeptidase / affinage / fromage