Burdett I D, Murray R G
J Bacteriol. 1974 Jul;119(1):303-24. doi: 10.1128/jb.119.1.303-324.1974.
Septa can be demonstrated in sections of Escherichia coli strains B and B/r after fixation with acrolein and glutaraldehyde. The septum consists of an ingrowth of the cytoplasmic membrane and the mucopeptide layer; the outer membrane is excluded from the septum until the cells begin to separate. Mesosomes have also been observed. The septum is highly labile and, except in the chain-forming strains, E. coli D22 env A and CRT 97, not easily preserved by standard procedures. The labile nature of the septum may be due to the presence of autolysin(s) located at the presumptive division site. Blocking division by addition of ampicillin (2 to 5 mug/ml) to cells of E. coli B/r produces a bulge at the middle of the cells; bulge formation is stopped by addition of chloramphenicol. Cephalosporins also induce bulge formation but may stop cell elongation as well as division. Bulge formation, due to the presumed action of an autolysin(s), may be an initial step in the septation sequence when the mucopeptide is modified to allow construction of the septum. In a nonseptate filament-forming strain, PAT 84, which ceases to divide at 42 C, bulge formation only occurs in the presence of ampicillin at the time of a shift-down at 30 C or at 42 C in the presence of NaCl (0.25 to 0.34 M). Experiments with chloramphenicol suggest that the filaments are fully compartmentalized but fail to divide owing to the inactivation, rather than loss of synthesis, of an autolysin at 42 C.
用丙烯醛和戊二醛固定大肠杆菌B株和B/r株后，在切片中可显示出隔膜。隔膜由细胞质膜和粘肽层向内生长形成；直到细胞开始分离，外膜才参与隔膜形成。也观察到了间体。隔膜非常不稳定，除了形成链状的菌株、大肠杆菌D22 env A和CRT 97外，用标准方法不易保存。隔膜的不稳定性质可能是由于在假定的分裂位点存在自溶素。向大肠杆菌B/r细胞中添加氨苄青霉素（2至5微克/毫升）阻断分裂会在细胞中部产生一个凸起；添加氯霉素可阻止凸起形成。头孢菌素也会诱导凸起形成，但可能同时阻止细胞伸长和分裂。由于假定的自溶素作用而形成的凸起，可能是当粘肽被修饰以允许构建隔膜时，隔膜形成序列中的初始步骤。在非隔膜丝状形成菌株PAT 84中，该菌株在42℃时停止分裂，只有在30℃或42℃下存在氯化钠（0.25至0.34M）且转移温度降低时，在氨苄青霉素存在的情况下才会形成凸起。氯霉素实验表明，这些细丝完全分隔，但由于在42℃时自溶素失活而非合成丧失，导致无法分裂。
