| abstract |
(57) [Summary] [Solution] Bacillus subtili After improving the vitamin K 2 productivity of the Bacillus natto belonging to s) by a mutation treatment or a spontaneous mutation treatment, the natto bacteria are subjected to a selective medium, in particular, a selective medium containing an analog of dihydroxynaphthoic acid. Isolate and select a mutant natto having excellent storage stability and use it to produce natto. According to the present invention, it is possible to stably provide natto containing vitamin K 2 , which is expected to have a bone-strengthening effect, and in particular, MK # 7. |