Anotace:
The commercial use and unrestricted disposal of synthetic dyes in soil and water-bodies, following the industrial revolution, has led to a major threat towards environmental safety. The azo-dye, Remazol Black B (RBB) is one of the most commonly used synthetic reactive dyes in textile industries. In the present study, the decolourization and biodegradation of RBB were investigated using a bacterium isolated from the marine environment, which was later identified as Pseudomonas aeruginosa AR-7 by 16S rRNA analysis. P. aeruginosa AR-7 showed 99% decolourization at 100mg/L dye concentration when cultured at optimum conditions of incubation i.e., 96h at 37⁰C under static conditions using minimal salts medium (pH 7-9) supplemented with 0.1% glucose and yeast extracts. However, the dye degradation ability of the isolate was reduced to 29% on increasing the dye concentration to 500mg/L. In addition, P. aeruginosa AR-7 showed decolourization and degradation of RBB in wastewater obtained after dyeing a cotton fabric. In further experiments, the Fe3O4 nanoparticles were synthesized using co-precipitation method and were used to immobilize the cells of P. aeruginosa AR-7 by adsorption, in order to compare the RBB degrading abilities of the free and coated cells. The prepared nanoparticles (50-150nm) were characterized by FTIR and SEM analysis to study its structural properties. Also, upon magnetization studies using SQUID magnetometer, Fe3O4 nanoparticles were shown to have a magnetization of about 63emu/g. Interestingly, the coated cells not only showed better degradation ability of RBB but also produced simpler products such as alkane, carboxylic acids, ketone, etc. on complete degradation. On the other hand, the free cells mainly produced esters as indicated by the comparison of GC-MS results.