Immobilization of EreB on Acid-Modified Palygorskite for Highly Efficient Degradation of Erythromycin.

Erythromycin is one of the most commonly used macrolide antibiotics. However, its pollution of the ecosystem is a significant risk to human health worldwide. Currently, there are no effective and environmentally friendly methods to resolve this issue. Although erythromycin esterase B (EreB) specifically degrades erythromycin, its non-recyclability and fragility limit the large-scale application of this enzyme. In this work, palygorskite was selected as a carrier for enzyme immobilization. The enzyme was attached to palygorskite via a crosslinking reaction to construct an effective erythromycin-degradation material (i.e., EreB@modified palygorskite), which was characterized using FT-IR, SEM, XRD, and Brunauer-Emmett-Teller techniques. The results suggested the successful modification of the material and the loading of the enzyme. The immobilized enzyme had a higher stability over varying temperatures (25-65 °C) and pH values (6.5-10.0) than the free enzyme, and the maximum rate of reaction (V) and the turnover number (k) of the enzyme increased to 0.01 mM min and 169 min, respectively, according to the enzyme-kinetics measurements. The EreB@modified palygorskite maintained about 45% of its activity after 10 cycles, and degraded erythromycin in polluted water to 20 mg L within 300 min. These results indicate that EreB could serve as an effective immobilizing carrier for erythromycin degradation at the industrial scale.