光电型传感法快速检测食品中大肠杆菌

Development of Photoelectric Sensor for Detection of E. coli

大肠杆菌可在异丙基-β-D-硫代吡喃半乳糖苷(IPTG)的诱导下分泌β-半乳糖苷酶,β-半乳糖苷酶特异性的催化氯酚红-β-D-吡喃半乳糖苷(CPRG)生成氯酚红(CPR)发生显色反应,而反应颜色的深浅和大肠杆菌的浓度具有一定的对应关系,从而建立检测大肠杆菌的光电型传感方法。结果表明:用光电传感方法检测大肠杆菌,最适反应时间4h、最适反应pH7.5。样品中细菌浓度的对数与反射光信号值之间呈现良好的对应关系(R=-0.98944,P<0.01),线性方程为Y=1426.10485-97.23368X,检测限可达104CFU/mL。基于颜色反应的光电传感方法检测大肠杆菌具有快速、简便、成本低廉等优点,具有良好的研发和应用前景。

E. coli secretes -galactosidase under the induction of isopropyl-β-D-thiogalactopyranoside （IPTG）. The β-galacosidase catalyzes chlorophenol ReD-β-D-galactopyranoside （CPRG） to form chlorophenol red （CPR） along with a color reaction. Based on the significant correlation between intensity of the color change from the reaction and the concentration of E. coli, a photoelectric sensor for detecting E. coli was developed. The results showed that the optimal pH for the reaction system was 7.5 and the optimal time for enzymatic reaction was 4 h. The logarithm value of bacterial concentration in samples presented a significant correlation with the reflected light signal value （R = --0.98944, P 〉 0.01）, the linear equation was Y= 1426.10485 -- 97.23368X. The detection limit was 104 CFU/mL. The photoelectric sensor based on color reaction can provide a quick, simple and cheap way to detect E. coil in food samples and therefore deserves further development and application.