To provide a fermented fermentation technology of natto having a strong umami caused by a nucleic acid-based umami ingredient, and at the same time without deterioration of "wear thickness" and "yarn elasticity".SOLUTION: The characteristics of producing nucleic acid-based umami (adenylic acid) in natto during the process of natto fermentation and deterioration of the basic quality characteristics of natto such as "wear thickness" and "yarn elasticity" Bacillus natto having a characteristic which is unlikely to be produced, a method for producing a nucleic acid-based umami ingredient-rich natto by carrying out natto fermentation using said strain of fermented soybean, and a method for producing a nucleic acid-based umami component in natto during the course of fermentation of natto Natto, which has a content of adenylic acid relative to natto of 7 mg / 100 g or more, exhibits a strong umami taste due to the adenylate, and natto containing a high content of umami ingredients of a nucleic acid type.[Effect] It is possible to manufacture and provide natto containing a nucleic acid-based umami taste component exhibiting umami with a nucleic acid-based umami component (adenylic acid).(FIG.【課題】核酸系うま味成分によるうま味が強く、同時に「被りの厚さ」、「糸の弾力」の劣化がない納豆発酵技術を提供する。【解決手段】納豆発酵の過程で納豆中に核酸系うまみ成分(アデニル酸)を産生させる特性と、納豆の基本的な品質特性である「被りの厚さ」、「糸の弾力」を劣化させることがない特性を備えた納豆菌、該納豆菌を使用して納豆発酵を行うことによる核酸系うま味成分高含有納豆の製造方法、及び納豆発酵の過程で納豆中に核酸系うま味成分を産生させた納豆であって、納豆に対するアデニル酸の含量が7mg/100g以上であり、該アデニル酸による強いうま味を呈する核酸系うま味成分高含有納豆。【効果】核酸系うま味成分(アデニル酸)によるうま味を呈する核酸系うま味成分高含有納豆を製造し、提供することができる。【選択図】図2
