Biodegradation and decolorization of trypan blue azo dye by marine bacteria Vibrio sp. JM-17

Marine microorganisms have shown the capability of azo dye degradation that is used in the tex-tile and tanning industries and cause harmful environmental effects. In the present study, we iso-lated Vibrio sp. from the marine environment which decolorizes trypan blue dye (direct blue 14). The decolorization by Vibrio sp. was 90.33% in 6 day at 500 mg L-1 of dye concentration. The study of environmental parameters showed Vibrio sp. as well adapted bacterial isolate in trypan blue degradation and capable of decreasing dye load in industrial effluent. The high-performance liquid chromatography (HPLC) results showed a complete conversion of the major peak into the two new peaks. The formation of new peaks was further confirmed by functional group (S=O, C-N, C-O, OH group) analysis by Fourier-transform infrared (FTIR) spectroscopy. The gas chro-matography-mass spectrometry (GC-MS) showed less harmful small molecules i.e., the formation of by-products (alkane, alkene, fatty acid and benzene) after trypan blue dye degradation by bac-terial isolate. Enzyme assay showed major involvement of azoreductase and tyrosinase in the degradation of trypan blue dye. In the proposed pathway, the decrease in toxicity of direct blue -14 dye by destabilization of the di-azo bond and formation of the less harmful by-product as ben-zoic acid. The toxicity analysis of dye-degraded by-products (DDP) at different concentrations (1-25%) carried on seeds of Vigna radiata showed 100% of seed germination. Similarly, the toxic-ity of DDP at a 5% concentration was studied on edible seaweed Ulva lactuca which showed an in-crease in daily growth rate (DGR) with an increase in content of both chlorophyll a and chloro-phyll b after 10 days of incubation. The results of the present study showed that bacterial isolate Vibrio sp. is capable of degradation of trypan blue dye with an environmentally friendly ap-proach.