Laccase enzymatic decolorization and degradation of Azo dyes

Background and Aim : Among all dyes used in textile and related industries, azo dyes are favorite ones and water pollution after discharging the effluents to water bodies is a major problem of using them. Halotolerant bacteria, Bacillus sp. strain WT. is known for thermostable laccase production. Also there is enough data on reduction on toxicity of azo dyes solutions after treatment with Bacillus sp. This work describes activity of the laccase from Bacillus sp. strain WT.Methods : Bacillus sp. WT was cultured in a solid medium containing ۳% NaCl salt, for ۷۲ hours to check its tolerability and ensure that the strain was tolerable to the salt. In order to ensure that the desired strain contains the laccase enzyme, it was cultured in nutrient agar (containing Manganese) and incubated for ۷۲ hours. A microbial suspension was prepared at ۵۰ mM Tris and tested with a specific Laccase enzyme (ABTS) substrate, which was positive. decolorization was checked at pH ۵ to ۸ (۳۷ °C for ۲ hours), for three azo dyes (Solphenyle blue, Remazol belack, Solphenyle green).Results : The highest percentage of decolorization was observed at pH ۵ for all three dyes, Solphenyle blue about ۴۳.۷۵%, Rimazole Black about ۸۵.۸۵%, Solphenyle green about ۹۶.۹۶%.Conclusion : According to the results, the highest percentage of decolorization was observed in the three azo dyes used in acidic conditions, pH ۵ to ۷.

کلیدواژه ها:

Laccase ، Halotolerant bacteria ، Bacillus sp. strain WT ، azo dyes