Microbial Degradation and Decolorization of Methyl Orange Dye by an Application of Pseudomonas Spp. ETL-1982

Abstract

The increasing demand for colorfast and non fading textiles leads to continuous growth in the use of reactive dyes, the majority of which are azo dyes. Reactive dyes present in exhausted dye baths and rinsing water are not recyclable and scarcely biodegradable due to their various substituent. Increasing concern about the direct discharge of untreated dye house liquors to water bodies in developing countries and increasingly stringent regulations for textile wastewater in industrial nations has accelerated the need for new treatment schemes. Existing physical and chemical technologies are expensive and often produce large amounts of solid waste. There is a need to find alternative methods of treatment that are effective in removing dyes from large volumes of effluent and are low cost such as biological or combination system. A bacterium identified as Pseudomonas spp. ETL-1982 was isolated from dye contaminated soil. This strain rapidly decolorized a methyl orange azo dye solution. Features of the decolorizing process related to biodegradation and biosorption were also studied. The dye was efficiently decolorized in static compared to shaked cultures. The bacterium exhibited a remarkable color removal capability over a wide range of dye concentration (40-120 mg/l), pH (4-10) and temperatures (30-40°C). Dye removal appears to proceed by both enzymatic reductions associated with biosorption process as shown by effect of Chloramphenicol and Penicillin G on process and variation of UV - visible spectra of Azo dye solution after decolorizing cultivation with isolate. The Pseudomonas spp. ETL-1982 decolorized the repeated addition of methyl orange dye up to five cycles with variable decolorization rate (9-91%).