Wutor V C, Togo C A, Pletschke B I
Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa.
Chemosphere. 2007 Jun;68(4):622-7. doi: 10.1016/j.chemosphere.2007.02.050. Epub 2007 Apr 11.
The presence of coliforms in polluted water was determined enzymatically (in situ) by directly monitoring the activity of beta-d-galactosidase (B-GAL) through the hydrolysis of the yellow chromogenic subtrate, chlorophenol red beta-d-galactopyranoside (CPRG), which produced a red chlorophenol red (CPR) product. The objectives of this study were to monitor the effect of compounds commonly found in the environment and used in water treatment on a B-GAL CPRG assay and to investigate the differences between the environmental B-GAL enzyme and the pure commercial enzyme. Environmental B-GAL was optimally active at pH 7.8. Two temperature optima were observed at 35 and 55 degrees C, respectively. B-GAL activity was strongly inhibited by silver and copper ions. While calcium and ferrous ions at lower concentrations (50-100mgl(-1)) increased the enzyme activity, a reduction was observed at higher concentrations (200mgl(-1)). Sodium hypochlorite, normally used in rural areas to disinfect water gradually decreased B-GAL activity at concentrations between 0 and 5600ppm for both the commercial and environmental enzymes. B-GAL from the environment behaved differently from its commercially available counterpart.
通过直接监测β-d-半乳糖苷酶（B-GAL）的活性来酶促（原位）测定污水中大肠菌群的存在，该活性通过黄色显色底物氯酚红β-d-吡喃半乳糖苷（CPRG）的水解来实现，水解会产生红色的氯酚红（CPR）产物。本研究的目的是监测环境中常见的以及用于水处理的化合物对B-GAL CPRG测定的影响，并研究环境B-GAL酶与纯商业酶之间的差异。环境B-GAL在pH 7.8时活性最佳。分别在35和55摄氏度观察到两个温度最佳值。B-GAL活性受到银离子和铜离子的强烈抑制。虽然较低浓度（50 - 100mg l⁻¹）的钙离子和亚铁离子会增加酶活性，但在较高浓度（200mg l⁻¹）时会观察到活性降低。通常在农村地区用于水消毒的次氯酸钠，对于商业酶和环境酶，在0至5600ppm的浓度范围内都会使B-GAL活性逐渐降低。来自环境的B-GAL与其市售对应物表现不同。
