Decolourisation of Reactive Red 120 by a Novel Bacterial Consortium: Kinetics and Heavy Metal Inhibition Study

The Juru River is one of the most polluted rivers in Malaysia. A dye-degrading bacterial consortium has been isolated from the river’s sediment. The influence of various metal ions on the growth rate of this bacterial consortium on the Reactive Red 120 dye was investigated. This consortium JR3, consist of <em>Pseudomonas aeruginosa</em> MM01, <em>Enterobacter</em> sp. MM05 and <em>Serratia marcescens</em> MM06 were able to decolourise up to 700 ppm of RR120 under an optimal condition with limited substrate available. Substrate inhibition kinetics was investigated and based on the best model Aiba, the maximum growth rate was 0.795 h-1, while the saturation constant, and inhibitory constant, were 0.185 % and 0.14 %, respectively. Chromium showed the least effect on the decolourisation of 200 ppm RR120 with 73.5% removal with bacterial growth of 11.461 log CFU/mL. Zinc was the second least effect followed by silver and lead, with the percentage of RR120 decolourisation of 63.8%, 54.6% and 50.5%, respectively. Meanwhile, cadmium, arsenic, and copper reduced the decolourisation of RR120 in consortium JR3 by half. Mercury strongly inhibited decolourisation by 32.5%. Based on the least inhibited heavy metal on RR120 decolourisation activity of consortium JR3, the best inhibition kinetic model was Levenspiel with a maximum growth rate at 0.632 h-1, while the saturation constant and inhibitory constants were 15.08 % and 0.5783 %, respectively. The metal-tolerant azo-dye-degrading bacterial consortium will be very useful in dye remediation in metal-laden polluted environment.