Physiological fluxes and antioxidative enzymes activities of immobilized Phanerochaete chrysosporium loaded with TiO2 nanoparticles after exposure to toxic pollutants in solution

Immobilized Phanerochaete chrysosporium loaded with TiO 2 nanoparticles (PTNs) are novel high-value bioremediation materials for adsorbing cadmium and for degrading 2,4-dichlorophenol (2,4-DCP). The real-time changes in H + and O 2 fluxes were measured using the noninvasive microtest technique (NMT). The H + influx increased after the addition of 2,4-DCP, and shifted to efflux following the addition of Cd 2+ . The O 2 flux decreased after the addition of both 2,4-DCP and Cd 2+ . A larger Cd 2+ flux was immediately observed after exposure to 0.5   mM Cd 2+ (−351.25   pmol   cm −2   s −1 ) than to 0.1   mM Cd 2+ (−107.47   pmol   cm −2   s −1 ). The removal of Cd 2+ by the PTNs increased more after treatment with the 0.5   mM exposure solution (27.6   mg   g −1 ) than with the 0.1   mM exposure solution (3.49   mg   g −1 ). The enzyme activities were analyzed to review the antioxidative defense system of PTNs in a solution containing various concentrations of Cd 2+ . The activities of the coenzyme nicotinamide adenine dinucleotide (NADH) oxidase as well as the enzyme catalase (CAT) plateaued at 6.5   U   g −1 FW and 9.7   U   g −1 FW, respectively, after exposure to 0.25   mM Cd 2+ . The activity of superoxide dismutase (SOD) increased gradually in solutions containing 0.1–0.6   mM Cd 2+ , and eventually reached a maximum (68.86   U   g −1 FW). These results illustrate how the antioxidative defense system and the physiological fluxes of PTNs respond to the stress caused by toxic pollutants .