Decolorization and detoxification of sulfonated azo dye C.I. Remazol Red and textile effluent by isolated Lysinibacillus sp. RGS

Abstract

A novel bacterium was isolated from the soil of Ichalkaranji textile industrial area. Through 16S rRNA sequence matching and morphological observation it was identified as Lysinibacillus sp. RGS. This strain has ability to decolorize various industrial dyes among which, it showed complete decolorization and degradation of toxic sulfonated azo dye C.I. Remazol Red (at 30°C, pH 7.0, under static condition) with higher chemical oxygen demand (COD) reduction (92%) within 6 h of incubation. Various parameters like agitation, pH, temperature and initial dye concentrations were optimized to develop faster decolorization process. The supplementation of cheap co-substrates (e.g., extracts of agricultural wastes) could enhance the decolorization performance of Lysinibacillus sp. RGS. Induction in oxidoreductive enzymes presumably indicates involvement of these enzymes in the decolorization/degradation process. Analytical studies of the extracted metabolites confirmed the significant degradation of Remazol Red into various metabolites. The phytotoxicity assay (with respect to plants Phaseolus mungo and Sorghum vulgare) revealed that the degradation of Remazol Red produced nontoxic metabolites. Finally Lysinibacillus sp. RGS was applied to decolorize mixture of dyes and actual industrial effluent showing 87% and 72% decolorization (in terms of decrease in ADMI value) with 69% and 62% COD reduction within 48 h and 96 h, respectively. The foregoing result increases the applicability of the strain for the treatment of industrial wastewaters containing dye pollutants.