Decolourisation and toxicity reduction of azo dye Bismarck Brown by newly isolated Pseudomonas aeruginosa, JKAK strain.

The decolourisation of Bismarck Brown dye by the newly isolated bacterial strain, Pseudomonas aeruginosa (JKAK), was studied at various parameters. Additionally, decolourisation of Bismarck Brown was studied using previously isolated strains; Bacillus sp. (AK1), Lysinibacillus sp. (AK2) and Kerstersia sp. (VKY1). The studies were carried out at temperature (35–50°C), dye concentration (200–800 mg/L), pH (5.5–10.5), metal ions (200–1000 mg/L) and NaCl (5–30 g/L). The optimum pH and temperature were 8.5 and 40°C, respectively. The strains decolourised over 53.75% of 800 mg/L Bismarck Brown after 24 h of incubation. The JKAK strain showed significant halotolerance and decolourised over 90% of the dye in the presence of 30 g/L NaCl. Further, JKAK decolourised over 86.4% of the dye in the presence of 1000 mg/L of Pb²⁺ and Zn²⁺ ions. The products of decolourisation were identified as aromatic amines and showed decreased phytotoxicity when compared to the untreated dye. [ABSTRACT FROM AUTHOR]