Biodegradation of Congo Red dye by a mixed culture of Escherichia coli and Pseudomonas aeruginosa under anaerobic conditions

Abstract

The decolorization of azo dye; Congo Red (CR), in use in textile industries, were investigated using two facultative microorganism (Escherichia coli and Pseudomonas aeruginosa) under anaerobic and aerobic conditions. Forty milligram per liter of dyes and 10 g of yeast extract contained in a synthetic medium were used and incubated for 7 days. Simultaneous biomass activity and colour removal performance was monitored during batch assays. The effects of two different microorganisms and aerobic/anaerobic conditions on decolourization were recorded with the monitoring of pH, color and concentration. The aromatic amines (as benzidine) and sulphate arising from the metabolites of anaerobic bio-degradation of dyes and the recoveries of these aromatic amines were also monitored. High benzidine recoveries indicated the accumulation of aromatic amines under aerobic conditions. The colour of the Congo red dye was removed up to 90% and 86%, respectively, by Escherichia coli and Pseudomonas aeruginosa at the end of anaerobic incubation