Effect of Triton X-100 on Shiraia laccase production and its application in triclosan biodegradation

Abstract

Shiraia bambusicola, a bambusicolous fungus exhibits an excellent capability to produce the novel photosensitizer hypocrellin for photodynamic therapy. Recently, Shiraia species attract increasingly more attention as fungal laccase producer due to its extensive application in bioremediation. In this study, the laccase production was enhanced by the addition of surfactants in mycelium culture of Shiraia sp. S9. We sought to explore the mechanism for the surfactant induction and apply the culture to biodegrade a micropollutant triclosan. Triton X-100 was found to induce the burst of reactive oxygen species (ROS), increase membrane permeability and up-regulate laccase-related gene expression, leading to the enhanced laccase production to 9.2 × 104 U/L, about 108-folds over the control. After 2 days of Shiraia mycelium culture under Triton X-100 treatment (0.8%, w/v), the degradation and adsorption rate of triclosan reached 80.71% and 10.21%, respectively. Furthermore, Triton X-100-induced cloud point system was established after the biodegradation, which could further enrich triclosan in the coacervate phase. With the help of a combination of triclosan biodegradation and the cloud point extraction, triclosan was almost completely removed (99.88%) from water phase in the culture. To our knowledge, this is the first report on the biodegradation of triclosan by Shiraia mycelium culture. Our study provided insights into elicitation of surfactants on fungal laccase production and a new strategy for triclosan biodegradation.