Isolation and screening of azo dye reactive violet 5R degrading bacteria from textile sludge

Abstract

Azo dyes account for the majorly produced synthetic dye substances in industries. They are extensively used in the textile, leather, pharmaceutical and cosmetics industries, posing a threat to all life forms. Harmful chemicals are consistently used in the dying process. These include dioxin, toxic heavy metals such as chrome, copper, zinc and formaldehyde. These are proven to be potential carcinogens. The dyes also adsorb and reflect the sunlight entering the water, thereby interfering with the aquatic species growth and hindering photosynthesis. The solution to these remedies are generally available within the environment. There are certain microorganisms which have the ability to degrade these azo dyes. In this study three bacterial strains, Streptococcus equi subsp. zooepidemicus, Brevibacillus centrosporus, Paenibacillus azoreducens, have been extracted from the sludge samples collected from Ridesha Textile Industry, Bhaluka. ABIS microbiology software (Advanced Bacterial Identification Software) was used to justify and determine the identity of these bacteria with the aid of results obtained from the biochemical tests that were undertaken. They have remarkably reacted to the azo dye Reactive Violet 5R. They have decolorized this dye with each of them producing unique results. The decolorization rate differed for every organism inoculated into the azo dye, reactive violet 5R. This decolorization rate was also different for the various concentrations of the same dye. Brevibacillus centrosporus displayed a decolorization rate of 94.55%, 90.79%, 91.17% when inoculated and incubated in an SM broth containing the azo dye reactive violet 5R at 1% (v/v), 3% (v/v), 5% (v/v) concentrations for a consecutive 5 days. Paenibacillus azoreducens projected a decolorization rate of 85.63%, 86.48%, 38.81% for the respective concentrations, 1% (v/v), 3% (v/v), and 5% (v/v) of the azo dye reactive violet 5R. Streptococcus equi subsp zooepidemicus produced intriguing results where the decolorization rates were 67.78%, 21.69%, 40.10% for the respective concentrations 1% (v/v), 3% (v/v) and 5% (v/v) of the azo dye reactive violet 5R, but the rate of growth of this organism in the SM broth media was much higher as proven by the absorbance rates achieved in the consecutive 5 days of inoculation and incubation. The organisms obtained after conducting this study can be used as a biological consortia for the treatment of the textile effluents. In the future, the genes responsible for the dye degrading characteristics can be isolated from their hosts and with the help of recombinant technology it