Carvalho M E, Gonçalves M H, Silva M T
Instituto de Ciências Biomédicas, Abel Salazar, Largo da Escola Médica, Porto, Portugal.
J Gen Microbiol. 1987 Apr;133(4):985-93. doi: 10.1099/00221287-133-4-985.
Autolysis of exponential-phase Streptococcus faecium cells was promoted by pretreating the bacteria (freezing-thawing; -70 degrees C) in Tris buffer, followed by incubation at 37 degrees C in the same buffer. The effect was dependent on Tris concentration. The pretreatment provoked ultrastructurally visible damage with extensive loss of K+ and leakage of UV-absorbing components. No autolysis was observed when the bacteria frozen-thawed in Tris were incubated in the presence of the autolysin inhibitor N-bromosuccinimide nor when they had been grown in the presence of chloramphenicol or tetracycline. Furthermore, two autolytic-defective mutants, EC31 and EC78, isolated from S. faecium, did not autolyse when frozen-thawed and incubated in Tris. Freezing-thawing in Tris, however, imparted extensive cell damage to the mutants and to the antibiotic-treated bacteria as well as considerable leakage of K+ and UV-absorbing materials. These observations indicate that the lysis of S. faecium reported above is due to the activity of the endogenous bacterial autolysin. Induction of autolysis of S. faecium by freezing-thawing was also observed, although to a lesser extent, when Tris was replaced by imidazole.
通过在Tris缓冲液中对处于指数生长期的粪肠球菌细胞进行预处理（冻融；-70℃），然后在相同缓冲液中于37℃孵育，可促进细胞自溶。该效应取决于Tris浓度。预处理引发了超微结构可见的损伤，伴有大量钾离子流失和紫外线吸收成分泄漏。当在Tris中冻融的细菌在自溶素抑制剂N-溴代琥珀酰亚胺存在下孵育时，未观察到自溶现象；当细菌在氯霉素或四环素存在下生长时，也未观察到自溶现象。此外，从粪肠球菌中分离出的两个自溶缺陷突变体EC31和EC78，在Tris中冻融并孵育时不会自溶。然而，在Tris中冻融会给突变体、经抗生素处理的细菌造成广泛的细胞损伤，以及大量钾离子和紫外线吸收物质的泄漏。这些观察结果表明，上述粪肠球菌的裂解是由于内源性细菌自溶素的活性所致。当用咪唑替代Tris时，也观察到了冻融诱导粪肠球菌自溶的现象，尽管程度较轻。
