Efficient removal of various textile dyes from wastewater by novel thermo-halotolerant laccase

A novel thermostable/halotolerant metagenome-derived laccase (PersiLac2) from tannery wastewater was purified to remove textile dyes in this study. The enzyme was highly active over a wide temperature and pH range and maintained 73.35% of its initial activity after 30 days, at 50 °C. The effect of various metal and organic-solvent tolerance on PersiLac2 showed, retaining greater than 53% activity at 800 mM of metal ions, 52.12% activity at 6 M NaCl, and greater than 44.09% activity at 20% organic solvents. PersiLac2 manifested effective removal of eight different textile dyes from azo, anthraquinone, and triphenylmethane families. It decolorized 500 mg/L of Alizarin yellow, Carmine, Congo red and Bromothymol blue with 99.74-55.85% efficiency after 15 min, at 50 °C, without mediator. This enzyme could practically remove dyes from a real textile effluent and it displayed significant detoxification in rice seed germination tests. In conclusion, PersiLac2 could be useful in future for decolorization/detoxification of wastewater.