Using indigenous bacterial isolate Nesterenkonia lacusekhoensis for removal of azo dyes: A low-cost ecofriendly approach for bioremediation of textile wastewaters

Textile industry, a major trade in most developing countries, generates huge quantities of dye laden wastewater. Azo dyes, which are still used widely in textile industry are very toxic in nature and need to be removed from the wastewaters in a cost-effective manner. The conventional treatment methods are energy intensive and costly, making it necessary to explore low-cost methods for developing countries. The present study explores the potential application of an indigenous alkaliphilic bacterium Nesterenkonia lacusekhoensis EMLA3 for decolorizing eleven different types of azo dyes (Methyl red, Tartrazine, Ponceau S, Reactive red 35, Evans blue, Acid red 3R, Acid red, Violet C BL, Reactive violet, Red AG and Methyl orange) at high pH of wastewater. The strain showed remarkable ability to decolorize more than 90% of these azo dyes (100 mg l(-1) each) within 72 to 192 h through biodegradation in nutrient medium. The bacterium showed good growth (in terms of absorbance at 600/660 nm in the presence of the dyes indicating its tolerance toward these pollutants. The bacterium not just decolorized dye mixture at high pH in presence of indigenous microorganisms of wastewater, but also decreased Chemical Oxygen Demand (COD). It gradually lowered pH of the wastewater from initial 11.0 to 8.4 during the treatment. The microbially treated textile wastewater when tested for seed germination and growth of Vigna radiata showed no phytotoxicity. Use of this indigenous microbe thus opens new opportunities for treating dye containing wastewaters in an ecofriendly and economic manner.