Influence of soil properties on the biodegradation of 1,3,6,8-tetrachlorodibenzo-p-dioxin and fungal treatment of contaminated paddy soil by white rot fungus Phlebia brevispora

To examine the bioremediation potential of Phlebia brevispora in dioxin-contaminated soil, the fungus was inoculated into autoclaved soil that was contaminated with 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) or 1,3,6,8-tetrachlorodibenzo-p-dioxin (1,3,6,8-TCDD). Three types of soils, organic-rich soil (Andosol), organic-poor soil (Granitic Regosols), and paddy soil, were used for the construction of artificially contaminated soil to understand the influence of the soil property on fungal growth and dioxin degradation ability. Under a solid-state condition, although the growth of the fungus improved in organic-rich soil, the degradation of 2,7-DCDD was inhibited. Although the degradation of 1,3,6,8-TCDD under a solid-state condition was inhibited severely, 1,3,6,8-TCDD degradation was observed under a slurry-state condition in organic-poor soil. In the case of organic-rich soil, an increase in water content improved the 1,3,6,8-TCDD degradation efficiency. When the historically contaminated paddy soil was treated with P. brevispora under a slurry-state condition, 1,3,6,8-TCDD as the main contaminant degraded 50% after 90 d incubation.