For seeking genes associating with magnetosome biosynthesis mechanism in magnetotactic bacteria cells,a magnetosome-deleted NM7 of Magnetospirillum gryphiswaldense MSR-1 was obtained by mini-Tn5 lac Z2 transposon insertion mutation of conjugation experiment,and a 4642-bp fragment containing mini-Tn5 lac Z2 in NM7 was cloned includes the sequential steps of digestion,self-ligation,transformation and complete sequencing.