Diels L, De Smet M, Hooyberghs L, Corbisier P
Vlaamse Instelling voor Technologisch Onderzoek, Mol, Belgium.
Mol Biotechnol. 1999 Sep;12(2):149-58. doi: 10.1385/MB:12:2:149.
Historical emissions of old nonferrous factories lead to large geographical areas of metals-contaminated sites. At least 50 sites in Europe are contaminated with metals like Zn, Cd, Cu, and Pb. Several methods, based on granular differentiation, were developed to reduce the metals content. However, the obtained cleaned soil is just sand. Methods based on chemical leaching or extraction or on electrochemistry do release a soil without any salts and with an increased bioavailability of the remaining metals content. In this review a method is presented for the treatment of sandy soil contaminated with heavy metals. The system is based on the metal solubilization on biocyrstallization capacity of Alcaligenes eutrophus CH34. The bacterium can solubilize the metals (or increase their bioavailability) via the production of siderophores and adsorb the metals in their biomass on metal-induced outer membrane proteins and by bioprecipitation. After the addition of CH34 to a soil slurry, the metals move toward the biomass. As the bacterium tends to float quite easily, the biomass is separated from the water via a flocculation process. The Cd concentration in sandy soils could be reduced from 21 mg Cd/kg to 3.3 mg Cd/kg. At the same time, Zn was reduced from 1070 mg Zn/kg to 172 mg Zn/kg. The lead concentration went down from 459 mg Pb/kg to 74 mg Pb/kg. With the aid of biosensors, a complete decrease in bioavailability of the metals was measured.
老旧有色金属工厂过去的排放导致大面积的金属污染场地。欧洲至少有50个场地被锌、镉、铜和铅等金属污染。人们开发了几种基于颗粒分化的方法来降低金属含量。然而，得到的清洁土壤只是沙子。基于化学浸出或萃取或电化学的方法确实能得到一种无盐且剩余金属含量生物有效性增加的土壤。在这篇综述中，提出了一种处理重金属污染砂土的方法。该系统基于嗜碱假单胞菌CH34的生物结晶能力对金属的溶解作用。这种细菌可以通过产生铁载体来溶解金属（或提高其生物有效性），并通过金属诱导的外膜蛋白将金属吸附在其生物质中，还能通过生物沉淀作用吸附金属。将CH34添加到土壤泥浆中后，金属向生物质移动。由于这种细菌很容易漂浮，通过絮凝过程将生物质与水分离。砂土中的镉浓度可以从21毫克镉/千克降至3.3毫克镉/千克。同时，锌从1070毫克锌/千克降至172毫克锌/千克。铅浓度从459毫克铅/千克降至74毫克铅/千克。借助生物传感器，测得金属的生物有效性完全降低。
