The present invention addresses the problem of developing a technique for significantly suppressing the secondary fermentation of natto in a temperature range of no higher than room temperature (low-temperature range) and significantly prevents the quality deterioration of natto during storage and distribution. There is provided bacillus subtilis var. natto belonging to bacillus subtilis which has the following mycological properties: (1) when the bacillus subtilis var. natto is inoculated in a cooked soybean, etc., and the soy is kept at any temperature in a range of 37-53°C, the bacillus subtilis var. natto is favorably fermented, and natto having favorable flavor and stringiness can be produced (2) in a test for measuring the maximum width of a colony when the colony is inoculated in an agar medium (pH 7.0) containing 10% (w/v) phyton peptone and having any concentration of 3-4% (w/v), and is cultivated at a gas-phase temperature of 20°C for 48 hours, when the maximum width of the colony obtained by inoculating and cultivating K-2 strain (NITE BP-1577) is 2-4 mm, the maximum width of the colony obtained by inoculating and cultivating the bacillus subtilis var. natto is 1 mm or less and (3) the base sequence constituting 16SrDNA exhibits an identity of 99% or more with the base sequence described in SEQ ID NO: 1.La présente invention concerne le problème du développement dune technique visant à supprimer de manière significative la fermentation secondaire du natto dans une plage de température ne dépassant pas la température ambiante (plage de température basse) et éviter de manière significative la détérioration de la qualité du natto pendant le stockage et la distribution. Linvention concerne un bacillus subtilis var. natto appartenant à la famille des bacillus subtilis ayant les propriétés mycologiques suivantes : (1) quand le bacillus subtilis var. natto est inoculé dans un soja cuit, etc., et le soja est maintenu à nimporte quelle température dans la plage de
