Schaefler S, Malamy A
J Bacteriol. 1969 Aug;99(2):422-33. doi: 10.1128/jb.99.2.422-433.1969.
In the Enterobacteriaceae, beta-glucosides are catabolized by a complex system formed of three permeases, with partly overlapping substrate specificities, and two hydrolytic enzymes, phospho-beta-glucosidase A and B, which hydrolyze only phosphorylated beta-glucosides. Some Enterobacteriaceae such as Klebsiella-Aerobacter (Enterobacter) possess the complete system; others possess only parts of it or may have a cryptic phospho-beta-glucosidase activity without permease activity. A screening test applied to strains belonging to several genera of Enterobacteriaceae showed that strains of Citrobacter, Hafnia, and Serratia exhibit a degree of similarity in phospho-beta-glucosidase activity and inducibility which could be useful in their taxonomic characterization; others, such as Aerobacter aerogenes, Erwinia, and Proteus vulgaris, are more heterologous. Owing to the presence of inducible phospho-beta-glucosidases A and B in Citrobacter, the fermentation of beta-methyl glucoside and the fermentation of arbutin in mixture with cellobiose could be of diagnostic value in the differentiation of Citrobacter from Salmonella. Wild-type strains of Escherichia coli, Shigella, and Salmonella are phenotypically similar in their inability to catabolize beta-glucosides, the presence of constitutive P-beta-glucosidase A, and the lack of beta-glucoside permeases I and II. Their beta-glucoside-fermenting mutants show, however, a phospho-beta-glucosidase and beta-glucoside permease activity which is characteristic for mutants from each genus. The differences in the phenotype of the mutants reflect probable differences in the presence of cryptic genes in the wild-type strains and could be of evolutionary significance.
在肠杆菌科细菌中，β-葡萄糖苷由一个复杂的系统进行分解代谢，该系统由三种具有部分重叠底物特异性的通透酶以及两种水解酶——磷酸-β-葡萄糖苷酶A和B组成，这两种水解酶仅水解磷酸化的β-葡萄糖苷。一些肠杆菌科细菌，如克雷伯菌-气杆菌属（肠杆菌属）拥有完整的系统；其他细菌仅拥有该系统的部分组成部分，或者可能具有隐秘的磷酸-β-葡萄糖苷酶活性但没有通透酶活性。一项针对肠杆菌科几个属的菌株进行的筛选试验表明，柠檬酸杆菌属、哈夫尼亚菌属和沙雷菌属的菌株在磷酸-β-葡萄糖苷酶活性和诱导性方面表现出一定程度的相似性，这可能对它们的分类鉴定有用；其他细菌，如产气气杆菌、欧文氏菌和普通变形杆菌，则更为异源。由于柠檬酸杆菌中存在可诱导的磷酸-β-葡萄糖苷酶A和B，β-甲基葡萄糖苷的发酵以及熊果苷与纤维二糖混合发酵可能对柠檬酸杆菌与沙门氏菌的鉴别具有诊断价值。大肠杆菌、志贺氏菌和沙门氏菌的野生型菌株在表型上相似，它们无法分解代谢β-葡萄糖苷，存在组成型的P-β-葡萄糖苷酶A，并且缺乏β-葡萄糖苷通透酶I和II。然而，它们的β-葡萄糖苷发酵突变体表现出磷酸-β-葡萄糖苷酶和β-葡萄糖苷通透酶活性，这是每个属突变体的特征。突变体表型的差异反映了野生型菌株中隐秘基因存在的可能差异，并且可能具有进化意义。
