PROBLEM TO BE SOLVED: To provide a Bacillus natto strain improved in poly-&gamma-glutamic acid productivity, and to provide a method for efficiently producing poly-&gamma-glutamic acid using the strain, and to provide a method for producing a poly-&gamma-glutamic acid-rich natto.SOLUTION: The activity of a cell wall lytic enzyme having poly-&gamma-glutamic acid lytic activity is made to decline to improve the poly-&gamma-glutamic acid productivity of Bacillus natto, thus enabling the efficient production of poly-&gamma-glutamic acid and enabling the production of poly-&gamma-glutamic acid-rich natto.COPYRIGHT: (C)2012,JPO&INPIT【課題】ポリ-γ-グルタミン酸生産能が向上した納豆菌の提供、および、該菌株を使用した効率的なポリ-γ-グルタミン酸の生産およびポリ-γ-グルタミン酸含量の多い納豆の製造。【解決手段】ポリ-γ-グルタミン酸分解活性を有する細胞壁溶解酵素の活性を低下させることにより、納豆菌のポリ-γ-グルタミン酸生産能を向上させ、効率的なポリ-γ-グルタミン酸の生産およびポリ-γ-グルタミン酸含量の多い納豆の製造を可能とする。【選択図】図1