Characterization of Dye Degrading Potential of Suspended and Nanoparticle Immobilized Cells of Pseudomonas Aeruginosa Ar-7

Abstract

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.

Biological Treatment of Real Textile Effluent Using Aspergillus flavus and Fusarium oxysporium and Their Consortium along with the Evaluation of Their Phytotoxicity

“…The results in the current study were similar to those of Surti and Ansari [ 54 ] who found that the GC–MS analysis of metabolites extracted from the MSM broth altered with 0.5-mL dye wastewater showed complete degradation of dye, as indicated by the comparison between GC–MS chromatogram of pure and degraded dyes. Jamil et al [ 70 ] also found that the GC–MS analysis indicates the complete breakdown of disperse violet 26 into inorganic compounds and ions of low molecular weight, for example, H 2 O, CO 2 , NO 3 , etc.…”

“…This might be attributed to the differences in electron distribution, charge density, or steric factors [ 19 ]. Consistent with this study, the maximum decolorization percentages of Remazol Black B were achieved in the presence of glucose (87.5%) and yeast extract (83.3%) from treatment with Pseudomonas aeruginosa [ 54 ]. Carbon and nitrogen sources were used to enhance enzyme production because they contain essential minerals and nutrients to be used as energy for growth [ 19 ].…”