Nodule bacteria are very good at biological nitrogen fixation. 根瘤菌是生物固氮的能手。
Within the nodule, rhizobia proliferate in very dense clusters of cells with altered morphology.These cell forms are called bacteroids. 在根瘤中,根瘤菌在形態改變的細胞中大量增殖緊密排列,這些,細胞組織被稱作類菌體。