Forsberg C W, Rogers H J
J Bacteriol. 1974 May;118(2):358-68. doi: 10.1128/jb.118.2.358-368.1974.
Two groups of mutants altered in lytic enzyme activities have been isolated from Bacillus licheniformis 6346 MH-1 by screening clones for halo production in agar plates containing cell wall conjugated with Procion brilliant red. In the first group which produced halos during colony formation, two were shown to contain three- and eightfold more muramyl-l-alanine amidase than the parent. These strains liberated amidase and intracellular alpha-glucosidase into the culture medium during exponential growth in liquid medium. Isolated walls had a normal qualitative composition and in autolysing liberated N-terminal amino acids and reducing groups. Wall preparations from the second group of mutants which did not produce halos lysed very poorly at pH 9.5, the optimal pH for amidase activity, and poorly at pH 5.5 even though they had similar endo-N-acetylglucosaminidase activities to the parent. Two of these strains that were also deficient in phosphoglucomutase had only 3 to 5% of the membrane-bound amidase activity compared with that in the parent. Cell walls of the phosphoglucomutase-deficient mutants treated with sodium dodecyl sulfate to inactivate endogenous lytic enzymes were dissolved at 10% of the rate of those from the parent by added amidase, but their sensitivities to lysozyme were similar. Those from one mutant had 10 to 20% of the amidase-binding capacity of parent walls, whereas its isolated mucopeptide was essentially inactive in this respect. The failure of these phosphoglucomutase-deficient mutants to autolyse is likely to be due to the combined effects of both low amidase activity and resistant walls. As a result, daughter cells are unable to separate and long chains are formed during exponential growth.
通过在含有与普施安亮红偶联的细胞壁的琼脂平板上筛选产生晕圈的克隆，从地衣芽孢杆菌6346 MH-1中分离出两组溶菌酶活性发生改变的突变体。在菌落形成过程中产生晕圈的第一组中，有两个突变体所含的胞壁酰-L-丙氨酸酰胺酶比亲本多3倍和8倍。这些菌株在液体培养基中指数生长期间将酰胺酶和细胞内α-葡萄糖苷酶释放到培养基中。分离出的细胞壁具有正常的定性组成，在自溶时释放出N-末端氨基酸和还原基团。第二组不产生晕圈的突变体的细胞壁制剂在酰胺酶活性的最佳pH值9.5时裂解很差，在pH 5.5时也很差，尽管它们的内切-N-乙酰葡糖胺酶活性与亲本相似。其中两个同时缺乏磷酸葡萄糖变位酶的菌株与亲本相比，膜结合酰胺酶活性仅为3%至5%。用十二烷基硫酸钠处理以灭活内源性溶菌酶的磷酸葡萄糖变位酶缺陷型突变体的细胞壁，通过添加酰胺酶以亲本细胞壁10%的速率溶解，但它们对溶菌酶的敏感性相似。来自一个突变体的细胞壁酰胺酶结合能力为亲本细胞壁的10%至20%，而其分离出的粘肽在这方面基本无活性。这些磷酸葡萄糖变位酶缺陷型突变体不能自溶可能是由于酰胺酶活性低和细胞壁抗性共同作用的结果。因此，子细胞无法分离，在指数生长期间形成长链。
