Department of Biology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China.
J Hazard Mater. 2010 Oct 15;182(1-3):792-800. doi: 10.1016/j.jhazmat.2010.06.106. Epub 2010 Jul 6.
Chromate [Cr(VI)] and azo dyes are common pollutants which may co-exist in some industrial effluents. Hence studies of biological treatment of industrial wastewater should include investigation of the co-removal of these two pollutants. Brevibacterium casei, which can reduce Cr(VI) in the presence of the azo dye Acid Orange 7 (AO7) under nutrient-limiting condition, was isolated from a sewage sludge sample of a dyeing factory. Response surface methodology, which is commonly used to optimize growth conditions for food microorganisms to maximize product(s) yield, was used to determine the optimal conditions for chromate reduction and dye decolourization by B. casei. The optimal conditions were 0.24 g/L glucose, 3.0 g/L (NH(4))(2)SO(4) and 0.2 g/L peptone at pH 7 and 35 degrees C. The predicted maximum chromate reduction efficiencies and dye decolourization were 83.4+/-0.6 and 40.7+/-1.7%, respectively. A new mechanism was proposed for chromate reduction coupling with AO7 decolourization by B. casei. Under nutrient-limiting condition, AO7 was used as an e(-) donor by the reduction enzyme(s) of B. casei for the reduction of Cr(VI). The resulted Cr(III) then complexed with the oxidized AO7 to form a purple coloured intermediate.
铬酸盐[Cr(VI)]和偶氮染料是常见的污染物，它们可能同时存在于一些工业废水中。因此，对工业废水进行生物处理的研究应该包括对这两种污染物的共同去除的研究。从一家染料厂的污泥样品中分离到了一种可以在偶氮染料酸性橙 7（AO7）存在下，在营养限制条件下还原 Cr(VI)的短杆菌属（Brevibacterium casei）。响应面法通常用于优化食品微生物的生长条件，以最大限度地提高产物产量，用于确定 B. casei 还原铬酸盐和染料脱色的最佳条件。最佳条件为 pH7 和 35°C 时，葡萄糖 0.24g/L、(NH4)2SO4 3.0g/L 和蛋白胨 0.2g/L。预测的最大铬酸盐还原效率和染料脱色率分别为 83.4+/-0.6%和 40.7+/-1.7%。提出了一种新的机制，用于 B. casei 还原铬酸盐与 AO7 脱色偶联。在营养限制条件下，AO7 被 B. casei 的还原酶用作 e(-)供体，用于还原 Cr(VI)。形成的 Cr(III)与氧化的 AO7 形成紫色中间产物。
