Asian Journal of Biology

Azo dyes represent a significant proportion of synthetic dyestuffs (70% of the world) and create immense environmental problems because of their toxic, mutagenic, and carcinogenic properties. Congo Red (CR) an azo dye acidic in character used extensively in the textile industry for being recalcitrant and toxic degradation products. The present study was designed to assess the biodegradation and decolorization capability of bacteria isolated from dye polluted wastewater collected from BSCIC industrial area, Rajshahi, Bangladesh. Three isolates (Yellow, Cream, and White) were found as Micrococcus sp., Proteus sp. and Staphylococcus sp from the confirmed result of Biochemical test produced by each isolate used independently and consortium. The yellow and cream isolates were gram-positive, while the white isolate was gram-negative. Functional analysis showed they varied in carbohydrate fermentation, motility and enzymatic activity. The bacterial community was found to be most efficient for decolorization at a concentration of 100 mg L⁻¹ CR in static condition within 48 hr incubation, pH range: pH 7–7.8 and temperature is 37 °C; the mechanism of this decolorization process has been explained through azo reductase that break azo bond. These results underline the potential of native bacterial consortia for low-cost and sustainable management strategies for azo dye–contaminated wastes, with implications relevant to yeast enzyme production at industrial scale by means of advanced biotechnological processes.