Decolorization and discovery of metabolic pathway for the degradation of Mordant Black 11 dye by Klebsiella sp. MB398.

Extensive utilization of the synthetic dyes in various industries is leading to water and soil contamination and ultimately impacting the humans. A research study was conducted for investigating the biodecolorization and biotransformation of Mordant Black 11 dye. For this purpose, potential of biofilm forming bacteria Klebsiella pneumoniae MB398 isolated from effluent outlets of Tops Food Industry, Hattar, Pakistan, was assessed to decolorize and transform Mordant Black 11 dye. Bacterial strain MB398 exhibited the capability of growing optimally at acidic pH (pH 6.0). Klebsiella pneumoniae MB398 efficiently decolorized Mordant Black 11 dye (64.55%) in aerobic environment at pH 6.0 and 37 °C over 24 h, which further increased to 75.35% over a period of 72 h of incubation. Strain MB398 also exhibited the capability of decolorizing Mordant Black 11 dye in the presence of cadmium (63.71%), chromium (61.78%), and copper (61.50%), respectively. UV-VIS spectrophotometric analysis, FTIR, and HPLC spectra were also indicative of biotransformation of dye molecules by Klebsiella pneumoniae MB398. GC-MS analysis of Mordant Black 11 dye revealed formation of 9 novel and unique metabolites including phenol,2,4-bis(1,1-dimethylethyl); 9-eicosene, (E); ethanol,2,2-(2-propenyloxy); acetic acid, benzene; 1-naphthol; methyl formate; valeraldehyde,2,4-dimethyl; and 7-hexadecene (Z). A possible metabolic pathway depicting the biotransformation of Mordant Black 11 dye by Klebsiella pneumoniae MB398 was projected. Findings of the current research study strongly suggest application of Klebsiella pneumoniae MB398 for developing large scale bioremediation strategies for the abatement of synthetic dyes to retain environmental sustainability in bioeconomic way.