Remazol reactive dye degrading Bacteria from freshwater fish of River Cauvery, Pallipalayam of Namakkal District, South India

Background Azo dye effluents cause severe pollution problems in soil and water and affect their flora and fauna throughout the world. The combination of dye degrading bacteria in the gut of freshwater fish has been considered a prospective approach towards the development of a sustainable environment. In the southernmost part of India, especially in the Namakkal District of Tamil Nadu state, urbanization and industrial development lead to various environmental issues. In lieu, most of the earlier works were carried out on the bacterial dye degradation from soil and water sources, least concentration on the dye degradation from fish gut flora. The objective of this study was to analyze the role of dye degrading bacteria in the gut of freshwater fish collected from the study area. Results We have studied the aerobic degradation of remazol yellow reactive dye by bacteria forming the gut flora of exotic fish Oreochromis mossambica from river Cauvery at Pallipalayam of Namakkal District, India. Eight dye degrading gut isolates viz. Pseudomonas sp. AD1, Bacillus sp. AD2, Staphylococcus sp. AD3, Staphylococcus AD4, Enterobacter sp. AD5, Escherichia coli AD6, Streptococcus sp. AD7 and Clostridium sp. AD8 were obtained capable of growing in azo dye incorporated in Basic mineral medium (BMM) medium. Optimization study was carried out for various parameters for the selected isolates. Based on the growth, maximum growth was seen in Pseudomonas sp. AD1 (in 0–24 h) and minimum in Escherichia coli .AD 6 (in 72–96 h). Pseudomonas sp. AD1, Enterobacter sp. AD5, and Bacillus sp. AD 2 exhibited efficient dye degradation during 0–96 h analysis which was confirmed by FTIR analysis. Loss of azo group stretch at 1572–76 cm −1 and 1429 cm −1 and presence of primary (–NH2–) and secondary amides (–NH2–), aliphatic –C–N– stretching and confirmed –C–S– stretching in FTIR analysis confirms the breaking down of the azo bond. Conclusion This study showed that there is a platform for using the bacterial flora of fish gut that paves a prominent way in the degradation of Azo dye.