Production and Application of Extracellular Laccase Produced by Fusarium oxysporum EMT

Laccase enzymes are multi-copper oxidases mainly produced by fungi, and have the ability to oxidize various phenolic compounds and discharge of synthetic dyes which considered toxic, carcinogenic, neurotoxic and mutagenic for human and environment. In the current study, highly active extracellular laccase was produced by fungus isolated from soil and identified as Fusarium oxysporum EMT (KT182633) using 18S rRNA gene as a molecular identification tool. Laccase was active optimally at pH 4-5 and 60 degrees C utilizing ABTS as an enzyme substrate. The decolorization of 3 synthetic dyes using direct fungal cultures was carried out at concentrations of 50 and 100 mg/L. The highest percentage of decolorization by laccase was exhibited for malachite green (98% and 96.8%) followed by Congo red (95% and 85%) and methyl orange (87.6% and 83%). The laccase was able to detoxify the cytotoxicity of the synthetic dyes against Caco-2 and fibroblast cells, which determined using a microculture tetrazolium assay (MTT) method. Additionally, the highest detoxification was revealed with malachite green that showed cell viability up to 100%. The outcomes demonstrated that laccase enzyme could be applied in environmental and agricultural applications. (C) 2016 Friends Science Publishers