Team:UCL/Project/About

The Problem: Azo Dyes in the Environment

Since their discovery by ? in ? azo dyes have become one of the most popular forms of synthetic colourant used in the industrial manufacture of a variety of products ranging from clothing and upholstery to cosmetics and tattoo ink as well as many more. Although azo-dyes are widely regarded as safe and stable forms of synthetic colourants some of them can take on dangerous properties when they are broken down by enzymes in the guts of organisms. In the textile industry today, annual production of dyestuff amounts to millions of tons globally and azo dyes represent two thirds of this value. Industrial leftover dye effluent is often not properly disposed of, or removed, during water treatment particularly is developing countries. This results in the accumulation of azo dyes in water bodies where are ingested by aquatic organisms and broken down into products that have been found to be mutagenic and carcinogenic. Despite this toxicity, little to no effort has been made to dispose of these leftover azo dyes more responsibly.

The Solution: Goodbye AzoDyes, UCL iGEM Team 2014

Our iGEM project developed a process for controllably degrading and detoxifying the excess azo-dye effluent at the source - the textile factories - by filtering the different toxic breakdown products elsewhere, before they ever reach the water systems. Our aim was to then convert these products into innoculous, and potentially useful, chemicals that can be used in other processes. We achieved this goal by introducing the genes for three enzymes related to the degradation of these dyes: azoreductase, laccase, and lignin peroxidase into a host E.coli cell to create an enhanced azo-dye decolourising organism.

We also designed an integrated end-of-pipe method for detoxifying effluent streams of dye factories using our engineered E. coli strain in a two-stage process to ensure optimal conditions for the degradation of azo dyes within a batch bioreactor system. The development of such a process would be an attractive and effective approach to dealing with azo dye contamination of the environment. As a financial incentive, we also looked at maximizing the profitability of various potential breakdown products as well as investigated the application of microbial fuel cell technology to an aerobic bioreactor system, for simultaneously detoxifying azo dyes and generating electricity. The potential for scalability of this method would present various economic and environmental advantages for industries that generate large amounts of dyestuff. The system we have developed could also be enhanced to become a modular bioprocess method for wastewater treatment of other toxic, normally recalcitrant chemicals.