Abstract This paper reports a facile electrochemical detection method for Escherichia coli (E. coli) that does not use DNA amplification or immunoassay. The detection principle is based on the activity of the β-galactosidase (β-gal) endogenous enzyme, which hydrolyzes p-aminophenyl-β- d- galactopyranoside (p-APG) into p-aminophenol. After E. coli consumes p-APG within 30 min, the remaining p-APG is oxidized on a gold electrode using cyclic voltammetry and square wave voltammetry. The β-gal expression level is increased through treatment with a β-gal expression inducer (isopropyl-β- d- thiogalactopyranoside), and the hydrolysis reaction of p-APG is facilitated through permeabilization treatment with sodium dodecyl sulfate. The calibration curve for E. coli has a working range of 102–104 colony-forming units per mL in nutrient broth buffer. The total assay time is less than 100 min. The successful application of this approach indicates the possibility of rapid detection.

中文翻译：

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通过内源性 β-半乳糖苷酶水解 p-APG 对大肠杆菌浓度进行伏安测量

摘要 本文报道了一种简便的大肠杆菌电化学检测方法，该方法不使用 DNA 扩增或免疫分析。检测原理基于β-半乳糖苷酶（β-gal）内源性酶的活性，该酶将对氨基苯基-β-d-吡喃半乳糖苷（p-APG）水解为对氨基苯酚。大肠杆菌在 30 分钟内消耗 p-APG 后，使用循环伏安法和方波伏安法在金电极上氧化剩余的 p-APG。β-gal 表达水平通过用 β-gal 表达诱导剂（异丙基-β-d-硫代吡喃半乳糖苷）处理而增加，并且通过用十二烷基硫酸钠进行透化处理促进 p-APG 的水解反应。大肠杆菌的校准曲线在营养肉汤缓冲液中的工作范围为每毫升 102–104 个菌落形成单位。总检测时间小于 100 分钟。这种方法的成功应用预示着快速检测的可能性。