Decolourisation of azo dyes by white-rot fungi (WRF) isolated in Singapore

It is widely known that white-rot fungi are suitable for treating a broad range of textile dye effluents because of their non-specific extracellular enzyme system. Three strains of white-rot fungi isolated in Singapore were screened for their ability to decolourise three azo dyes relative to the extensively studied species, Phanerochaete chrysosporium. The local isolate Trametes versicolor CNPR 8107 exhibited the greatest potential in treating dye effluents and its capabilities were investigated in detail. Dye decolourisation by CNPR 8107 was more favourable at 30 than at 37 °C, and compared favourably with P. chrysosporium as well as a reference commercial strain T. versicolor ATCC 20869. However, CNPR 8107 exhibited an initial lag in its dye decolourisation rate due to lower laccase production than ATCC 20869. A significant increase in decolourisation rate by CNPR 8107 was observed on day 5, following higher manganese-dependent peroxidase (MnP) production. More importantly, CNPR 8107 did not require strict secondary metabolism to produce ligninolytic enzymes. This non-stringent regulation on enzyme production is an advantage of CNPR 8107 over P. chrysosporium in decolourising industrial dye effluents where N-nutrients and carbonaceous source may still be present.