Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319‐5606 Volume 2, No.4, April 2013 _________________________________________________________________________________ www.borjournals.com Blue Ocean Research Journals 35 Biotransformation of a Textile AZO Dye Acid Yellow 25 by Marinobacter Gudaonensis AY-13 Shertate R.S., Research Scholar, P.G. Department of Microbiology and Research Center, Shri Shivaji Mahavidyalaya, Barshi – 413411, Dist. - Solapur, MS, India. Thorat P.R., Associate Professor, P.G. Department of Microbiology and Research Center, Shri Shivaji Mahavidyalaya, Barshi – 413411, Dist. - Solapur, MS, India. ABSTRACT Biotransformation of Acid Yellow 25 was carried out using Marinobacter gudaonensis AY-13(Accession No. HE970768) isolated from natural marine environment. The decolorization of the azo dye Acid Yellow 25 in nutrient broth and half strength nutrient broth having 8.0% salt concentration was up to 92.00% and 90.03% respectively in 24 hours. The decolorization of the dye by cell-free extract was found to be upto 80.13 % in 24 hours. The decolorization of the dye was also studied in presence of different co-substrates viz. 1% glucose, 1% yeast extract and 1% starch and found that percent decolorization was up to 92.77%, 94.00% and 92.05% respectively. From these results it can be concluded that, the isolate could decolorize the dye very effectively. The percent COD reduction of the dye by the isolate was 70.00%. The degradation products formed were analyzed by GC-MS technique and it was found that culture degraded Acid Yellow 25 to the products having molecular weights 98, 70, 112, 125, 140, 168, 186, 128, 141, 83, 111, 154, 72 and 155. The microbial toxicity study revealed that degradation products of Acid Yellow 25 were non-toxic to ecologically important microorganisms like Pseudomonas sp., Rhizobium sp. and Azotobacter sp. Keywords – Acid Yellow 25, Biodegradation, COD Reduction, GC-MS analysis, Marine Bacteria I. Introduction The Ocean, which is called the ‘Mother of origin of life’, is also the source of structurally unique natural products that are mainly accumulated in living organisms. Water is a huge resource on earth. Of all the water resources on earth, only 3% of it is not salty and two- third of fresh water exists in the form of glaciers and ice caps. Color present in the industrial effluent gives a direct indication that the water is polluted. Hence color is the first contaminant recognised in the textile effluent and it has to be removed before discharging into large bodies (Khadijah et al., 2009). Textile industries are usually located in places near to the sea, mainly for easy overseas transportation. However, the toxic effluents released by the industries causes a great challenge to the marine life. In a year, about 280,000 tonnes of textile dyes are let out into the environment worldwide most of which end up into the marine environment. The textile dyes profoundly disturbs the marine ecosystem, as they undergo chemical and biological changes. Their breakdown products might also be toxic to some aquatic organisms. Biodegradation causes mineralization of dyes to simpler inorganic compounds which are not lethal to life forms (Tripathi and Shrivastava, 2011). The basic step in the decolorization and degradation of azo dyes is breakdown of azo bonds, leading to removal of color and toxicity of the dye. The dye wastewaters can be treated by physicochemical methods, biological and microbiological methods. The major disadvantage of physicochemical methods has been largely due to the high cost, low efficiency, limited versatility, interference by other wastewater constituents (Van der Zee and Villaverde, 2005; Kaushik and Malik, 2009). Traditional wastewater treatment technologies have proven to be markedly ineffective for handling wastewater of synthetic textile dyes because of the chemical stability of these pollutants (Forgacs et al., 2004). Also these techniques generate a huge volume of sludge and cause secondary pollution due to the formation of sludge and hazardous by-products (Mohandass et al., 2007). The use of microorganisms for the removal of synthetic dyes from industrial effluents offers considerable advantages; the process is relatively inexpensive, the running costs are low, and the end products of complete mineralization are not (Forgacs et al., 2004) Thus, biodegradation is a promising approach for the remediation of synthetic dyes wastewater because of its cost effectiveness, efficiency, and environmentally friendly nature (Jirasripongpun et al., 2007; Shedbalkar et al., 2008; Gopinath et al., 2009). As a best alternative, much interest is now focused on biodegradation of dyes (Mcmullan et al., 2001; An et al., 2002). This study deals with biological decolorization and biodegradation of a