Caravelli Alejandro H, Giannuzzi Leda, Zaritzky Noemí E
Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CONICET-Fac Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
J Hazard Mater. 2008 Aug 15;156(1-3):214-22. doi: 10.1016/j.jhazmat.2007.12.014. Epub 2007 Dec 15.
Wastewaters produced by various industries may contain undesirable amounts of hexavalent chromium (Cr(VI)), as chromate and dichromate, a hazardous metal affecting flora and animals of aquatic ecosystems as well as human health. One removal strategy comprises the microbial reduction of Cr(VI) to Cr(III), a less soluble chemical species that is less toxic than Cr(VI). In this work, the ability to reduce Cr(VI) of Sphaerotilus natans, a filamentous bacterium usually found in activated sludge systems, was evaluated. In aerobic conditions, S. natans was able to efficiently reduce Cr(VI) to Cr(III) from dichromate solutions ranging between 4.5 and 80 mg Cr(VI)l(-1) in the presence of a carbonaceous source. A simultaneous evaluation of the microbial respiratory activity inhibition was also carried out to analyze the toxic effect of Cr(VI). Cr(VI) reduction by S. natans was mathematically modeled; chromium(VI) reduction rate depended on both Cr(VI) concentration and active biomass concentration. Although it is known that S. natans removes heavy metal cations such as Cr(III) by biosorption, the ability of this micro-organism to reduce Cr(VI), which behaves as an oxyanion in aqueous solutions, is a novel finding. The distinctive capacity to reduce Cr(VI) to Cr(III) than remain soluble or precipitated becomes S. natans a potential micro-organism to decontaminate wastewaters.
各行业产生的废水中可能含有过量的六价铬（Cr(VI)），以铬酸盐和重铬酸盐的形式存在，这是一种有害金属，会影响水生生态系统中的动植物以及人类健康。一种去除策略包括将Cr(VI)微生物还原为Cr(III)，Cr(III)是一种溶解度较低的化学物质，其毒性低于Cr(VI)。在这项工作中，评估了通常存在于活性污泥系统中的丝状细菌浮游球衣菌还原Cr(VI)的能力。在有氧条件下，浮游球衣菌能够在存在碳源的情况下，将4.5至80 mg Cr(VI)l(-1)的重铬酸盐溶液中的Cr(VI)有效还原为Cr(III)。还同时评估了微生物呼吸活性抑制情况，以分析Cr(VI)的毒性作用。对浮游球衣菌还原Cr(VI)进行了数学建模；六价铬还原率取决于Cr(VI)浓度和活性生物量浓度。虽然已知浮游球衣菌通过生物吸附去除重金属阳离子如Cr(III)，但这种微生物还原在水溶液中表现为氧阴离子的Cr(VI)的能力是一项新发现。将Cr(VI)还原为仍可溶解或沉淀的Cr(III)的独特能力使浮游球衣菌成为一种潜在的废水净化微生物。
