Exploiting the potential of plant growth promoting bacteria in decolorization of dye Disperse Red 73 adsorbed on milled sugarcane bagasse under solid state fermentation

Bioremediation of textile dyes adsorbed on agricultural solid wastes under solid state fermentation (SSF) using rhizospheric plant growth promoting microorganisms pose an ecofriendly, economically feasible and promising treatment approach. The purpose of this study was to adsorb azo dye Disperse Red 73 (DR73) on sugarcane bagasse (SCB) and its further bioremediation using consortium-RARB under SSF. The particle size of SCB 0.002 mm showed maximum adsorption (65%) for DR73. Kinetics of adsorption of DR73 on milled SCB follows pseudo-second order kinetics. The individual cultures of Rhodobacter erythropholis MTCC 4688, Azotobacter vinelandii MTCC 1241, Rhizobium meliloti NCIM 2757 and Bacillus megaterium NCIM 2054 showed 44, 28, 50 and 61% decolorization of DR73 in 48 h respectively; while the consortium-RARB showed complete decolorization in 48 h. Optimum moisture content, temperature and pH for decolorization of DR73 was found to be 90%, 30 °C and 6 respectively. DR73 biodegradation analysis was carried out using HPTLC, FTIR and HPLC. Phytotoxicity and genotoxicity studies revealed detoxification of DR73. Tray bioreactor study for decolorization of adsorbed DR73 on SCB suggests its implementations at large scale. Use of plant growth promoting bacteria's consortium under SSF for bioremediation of adsorbed dyes gives a novel ecologically sustainable approach.