A study on the dye degrading ability of Brevibacillus brevis US575 and Bacillus cereus F4810/72 isolated from tannery effluents

Owing to different anthropogenic activities of various types of industries like paper, textile, tannery, etc. significant quantities of water are released into the environment without proper treatment that have detrimental effects on living organisms. The azo dye acid blue113 is used extensively in the tannery industry. Therefore its removal from the waste water is of utmost importance. In our study, Brevibacillus brevis US575 and Bacillus cereus F4810/72 were isolated from tannery industries located at Bantala in the district of South 24 Paraganas, West Bengal. Preliminary data indicated that both of these isolates individually as well as in a consortium can degrade the selected dye maximally within 4 days. The experimental conditions for maximum dye degradation were optimized. Maximum decolourization was obtained at 100 mg/L initial dye concentration, pH 7.5–8, 37ᵒC temperature. The addition of various substrates like starch, sodium chloride, and ascorbic acid significantly increased the decolourization process. The isolates have been shown to produce a significant amount of indole acetic acid (14–26 μg/mL). The isolates also solubilize phosphate which is detected by the presence of a halo ring (diameter 8–14 mm). Inoculation of the isolates to plants grown in water containing the dye not only resulted in decolourization of the dye within 10 days but also significantly improved certain plant growth properties such as root length and shoot length. These results highlight that the bacterial isolates possessing dual traits could be used simultaneously for detoxification and bioremediation of toxic azo dye-containing industrial effluents and growth promotion in plants.