Growth, Oxidative Stress and Ability to Degrade Tetrabromobisphenol A of Phanerochaete chrysosporium in the Presence of Different Nano Iron Oxides

Abstract

In order to improve the performance of white rot fungi, especially the model species Phanerochaete chrysosporium in tetrabromobisphenol A (TBBPA) degradation, the strategy of synergizing Phanerochaete chrysosporium with nano iron oxides was considered; however, the effects of different nano iron oxides on Phanerochaete chrysosporium are still unknown. In this study, 20 nm γ-Fe2O3, 30 nm α-Fe2O3, 20 nm Fe3O4, and 200 nm Fe3O4 were used, and the fungal growth, oxidative stress, and ability to degrade TBBPA were monitored. The results showed that the addition of four nano iron oxides did not inhibit the growth of Phanerochaete chrysosporium. The effective antioxidant defense system of Phanerochaete chrysosporium could cope with almost all oxidative pressure induced by 200 nm Fe3O4. But when the size of nano iron oxide became significantly smaller or when the type of iron oxide changed from Fe3O4 to Fe2O3, a higher intracellular hydrogen peroxide (H2O2) content, lower intracellular superoxide dismutase (SOD) and catalase (CAT) activities and higher extracellular lactate dehydrogenase (LDH) activity were induced. When nano iron oxides synergized with Phanerochaete chrysosporium, the removal of TBBPA in all groups was slightly improved and mostly due to the degradation of TBBPA, with smaller iron oxides showing more enhancement for the degradation of TBBPA, while 200 nm Fe3O4 only enhanced the adsorption of TBBPA. The enhanced degradation of TBBPA showed no significant correlation with lignin-degrading enzyme activities but was closely correlated with the intracellular H2O2 concentration.