Every year, large amounts of dyes are produced and consumed in China. However, some dyes pose a threat to human health and ecological safety due to its toxicity and carcinogenicity. Treatment of dye-based effluents remains to be a challenge for environmental scientists.
With the supervision of Professor Jun Wang, Dr. Yuyi Yang of Wuhan Botanical Garden expressed azoreductase in E.Coli from S. oneidensis MR-1. The azoreductase was found to catalyze the azo bond cleavage efficiently with NADH as electron donor. To reduce the addition dose of NADH, an integrated enzyme system was constructed by azoreductase and glucose 1-dehydrogenase for both continuous generation of the cofactor NADH and azo dye removal. The results showed that 85% maximum relative activity of azoreductase in an integrated enzyme system was obtained at the conditions: 1 U azoreductase: 10 U glucose 1-dehydrogenase, 250 mM glucose, 1.0 mM NAD+ and 150 l M methyl red. Sensitivity analysis of the factors in the enzyme system affecting dye removal examined by an artificial neural network model showed that the relative importance of enzyme ratio between azoreductase and glucose 1 - dehydrogenase was 22%, followed by dye concentration (27%), NAD+ concentration (23%) and glucose concentration (22%), indicating none of the variables could be ignored in the enzyme system. Batch results show that the enzyme system has application potential for dye removal.
This work was supported in part by grants from the Science and Technology Project of Zhejiang Province (2010C13G2010074), National Natural Science Foundation of China (31070079), the Science and Technology Project of Zhejiang Province (2008C13014-3) , the International Cooperation Project in Science and Technology of Zhejiang Province (No. 2008C14038) and the National Key Technology Rand D Program (2012BAC17B04). Relevant results were published in Bioresource Technology (2013,130:517-521.) entitled "Construction of an Integrated Enzyme System Consisting Azoreductase and Glucose 1-Dehydrogenase for Dye Removal”.
sensitivity analysis (a) and batch experiment results
