DETECTION AND ANALYSIS OF EXTRACELLULAR AND INTRACELLULAR DEOXYRIBONUCLEASE ACTIVITIES IN LACTOBACILLUS-PLANTARUM

Extracellular endodeoxyribonuclease activities have been detected in c ulture supernatant fluids of several Lactobacillus plantarum strains. In the case of Lact. plantarum HER 1325 at least, the extracellular ac tivity is accompanied by a cytoplasmic restriction endonuclease. Among the secreted nuclease, the greatest activity was from Lact. plantarum ATCC 10241. This strain secretes an enzyme, with a molecular mass in the range 10-10 kDa, that cuts double-stranded DNA in a sequence-indep endent way by initially introducing single-strand nicks in supercoiled molecules, followed by linearization and complete degradation of the substrate.