Identification and characterisation of two novel azo dye degrading microorganisms from contaminated ground water and soil of a textile mill

Abstract

Bacterial isolates were tested for biodegradability potential of azodyes. S1 and S2 isolate effectively decolorised all azodyes tested within 72 hours. These isolates were later characterised as Achromobacter and Bacillus sp. The resistance traits on plasmid were evidenced from curing experiments. Sodiumdodecyl sulphate (SDS) and rifampicin (9 mg/ml) was found to be most effective curing agent. Achromobacter sp. was positive for tryptophanase, indole and citrate permease with ability to ferment glucose and produced gas. While, S2 showed the presence of tryptophanase, but found negative for the urease. Both the isolates were able to sustain salt concentration between 4%-10% suggesting moderately halotolerant. Bacillus sp. exhibited tolerance to heavy metal, zinc and arsenic up to 8 M; copper, cobalt and nickel to an extent of 500 mM. Efficient decolorising activity, heavy metal and salt tolerance capability indicates that isolated strains can be utilised effectively for the treatment of effluents in the dye industries.