PHAGE-RESISTANT LACTIC ACID BACTERIUM AND PHAGE DNA CLEAVING RESTRICTION ENZYME

摘要

PROBLEM TO BE SOLVED: To obtain the subject new lactic acid bacterium belonging to phage- resistant Streptococcus salivarius sp. thermophilus capable of producing phage DNA cleaving restriction enzymes, therefore useful for producing phage DNA cleaving restriction enzymes. SOLUTION: This new lactic acid bacterium [e.g. Streptococcus salivarius sp. thermophilus (FERM P-17215)] is such one as to belong to phage-resistant Streptococcus salivarius sp. thermophilus capable of producing phage DNA cleaving restriction enzymes, being useful for preventing damages due to phage infection in producing fermented dairy products including yogurt and cheese by making use of lactic acid bacteria, and for producing phage DNA cleaving restriction enzymes intended for gene recombination. This lactic acid bacterium is obtained by obtaining a sample containing Streptococcus from naturally acidified milk or the like through microscopic examination followed by culturing the sample to form a plenty of colonies from which a strain having the ability to cleave a phage DNA is then screened using phage DNA cleavage test method.