Mulchandani A, Kaneva I, Chen W
Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA.
Biotechnol Bioeng. 1999 Apr 20;63(2):216-23. doi: 10.1002/(sici)1097-0290(19990420)63:2<216::aid-bit10>3.0.co;2-0.
An improved whole-cell technology for detoxifying organophosphate nerve agents was recently developed based on genetically engineered Escherichia coli with organophosphorus hydrolase anchored on the surface. This article reports the immobilization of these novel biocatalysts on nonwoven polypropylene fabric and their applications in detoxifying contaminated wastewaters. The best cell loading (256 mg cell dry weight/g of support or 50 mg cell dry weight/cm2 of support) and subsequent hydrolysis of organophosphate nerve agents were achieved by immobilizing nongrowing cells in a pH 8, 150 mM citrate-phosphate buffer supplemented with 1 mM Co2+ for 48 h via simple adsorption, followed by organophosphate hydrolysis in a pH 8, 50 mM citrate-phosphate buffer supplemented with 0.05 mM Co2+ and 20% methanol at 37 degrees C. In batch operations, the immobilized cells degraded 100% of 0.8 mM paraoxon, a model organophosphate nerve agent, in approximately 100 min, at a specific rate of 0.160 mM min-1 (g cell dry wt)-1. The immobilized cells retained almost 100% activity during the initial six repeated cycles and close to 90% activity even after 12 repeated cycles, extending over a period of 19 days without any nutrient supplementation. In addition to paraoxon, other commonly used organophosphates, such as diazinon, coumaphos, and methylparathion were hydrolyzed efficiently. The cell immobilization technology developed here paves the way for an efficient, simple, and cost-effective method for detoxification of organophosphate nerve agents.
最近开发了一种改进的全细胞技术，用于解毒有机磷神经毒剂，该技术基于表面锚定有机磷水解酶的基因工程大肠杆菌。本文报道了这些新型生物催化剂固定在聚丙烯无纺布上及其在解毒受污染废水方面的应用。通过将非生长细胞在pH 8、150 mM柠檬酸-磷酸盐缓冲液（补充1 mM Co2+）中简单吸附48小时，然后在pH 8、50 mM柠檬酸-磷酸盐缓冲液（补充0.05 mM Co2+和20%甲醇）中于37℃进行有机磷水解，实现了最佳细胞负载量（256 mg细胞干重/克载体或50 mg细胞干重/平方厘米载体）以及随后对有机磷神经毒剂的水解。在分批操作中，固定化细胞在约100分钟内降解了100%的0.8 mM对氧磷（一种有机磷神经毒剂模型），比速率为0.160 mM min-1（克细胞干重）-1。固定化细胞在最初的六个重复循环中几乎保留了100%的活性，即使在12个重复循环后，经过19天且无任何营养补充的情况下，活性仍接近90%。除了对氧磷外，其他常用的有机磷，如二嗪农、蝇毒磷和甲基对硫磷也能被有效水解。这里开发的细胞固定化技术为一种高效、简单且经济有效的有机磷神经毒剂解毒方法铺平了道路。
