PROBLEM TO BE SOLVED: To provide a novel cyclic bacteriocin capable of extending a use-by date of a foodstuff, particularly pickles such as lightly pickled vegetables, a novel lactic bacterium capable of producing the cyclic bacteriocin, a method of producing a cyclic bacteriocin using the lactic bacterium, and a method of producing a foodstuff using the lactic bacterium.SOLUTION: The novel cyclic bacteriocin includes a structure of either, (1) a cyclic peptide comprising a specific amino acid sequence with its N-terminal leucine and its C-terminal tryptophan binding to each other or, (2) a cyclic peptide according to the cyclic peptide (1) with deletion, substitution or addition therein of one or more of amino acids and having antimicrobial activity.
