Harnessing coastal halophiles for azo dye biodegradation: Phylogenetic and spectroscopic evidence of efficient bioremediation

Halophilic bacteria from the east coast of Tamil Nadu, India, demonstrated efficient decolorization of methyl red
and methylene blue azo dyes. They are of special importance because the hydrolytic enzymes they produce are
usually stable, specific, and useful in conditions of high salinity and tidal variations. Many applications,
particularly bioremediation, use them due to their exceptional performance in a variety of harsh environments.
From the east coast of Tamil Nadu, India, halophilic bacteria were identified. Optimization of pH, temperature,
and salt concentration for growth was performed on the isolated halophilic bacteria. The decolorization of
methyl red and methylene blue azo dyes by identified halophilic bacteria was studied. The capacity of three of
the six halophilic bacterial strains that were isolated from marine sediments to decolorize the commonly used azo
dyes was impressive. Phenotypic description and phylogenetic research based on comparisons of 16S rRNA sequences identified these strains as members of Salinicoccus roseus, Bacillus altitudinis, and Staphylococcus warneri.
Azo dye Decolorization and degradation were possible for three of six isolated strains, methyl red, and methylene
blue azo dyes after 5 days of incubation in static culture. UV-Visible spectroscopy and FT-IR analyses of methyl
red and methylene blue, conducted before and after decolorization, confirmed both decolorization and structural
degradation. The results indicate that degradation primarily occurred through azoreductase-mediated cleavage
of the azo bonds.