PROBLEM TO BE SOLVED: To provide a method for obtaining native variants of lactic acid bacteria that produce, under standard fermentation conditions, at least about 1.2 times more vitamin K2 than the vitamin K2 produced by lactic acid bacteria strains cultured in the identical conditions.SOLUTION: There is provided a method including at least following steps: (a) a step of cultivating the lactic acid bacteria strain, under standard fermentation conditions, in a selecting medium which induces modification of redox state of cells； and (b) a step of selecting the variants in the situation which under identical fermentation conditions, at least about 1.2 times more vitamin K2 than the lactic acid bacteria strains cultured in the identical conditions are produced. There are also provided a method for producing food products, including fermented products and/or fresh diary products, enriched with vitamin K2, and the food products thus obtained.【課題】同一条件下で培養した乳酸菌株によって産生されるビタミンK2よりも、少なくとも約1.2倍、より多い量のビタミンK2を標準発酵条件下で産生する乳酸菌の天然変異体を得るための方法の提供。【解決手段】少なくとも以下の工程を含む方法である：ａ）細胞のレドックス状態の修飾を誘導する選択培地において、標準発酵条件下で該乳酸菌株を培養する工程；およびｂ）同一条件下で培養した該乳酸菌株よりも少なくとも1.2倍より多くのビタミンK2を産生する場合、該変異体を選択する工程を含む。さらに、ビタミンK2で強化された発酵製品および／またはフレッシュな乳製品を含む食品の製造方法、ならびにこのようにして得られる食品に関する。【選択図】なし
