Response to oxidative stress of Coriolus versicolor induced by exogenous hydrogen peroxide and paraquat

Abstract

Effects of exogenous hydrogen peroxide (H2O2) and paraquat (PQ) addition on the oxidative stress response of white-rot fungus Coriolus versicolor were investigated. Water solutions of H2O 2 and PQ were added to 7-day-old liquid cultures. The activities of extracellular ligninolytic enzyme, intracellular antioxidant enzyme and some biochemical parameters were determined up to 148 h after treatments. We found that the administration of 30 μM PQ and 6 mM H2O2 to Coriolus versicolor significantly stimulated the activities of manganese dependent peroxidase (MnP), lignin peroxidase (LiP), and laccases (LAC) in comparison to the control value (without PQ and H2O2). Administration of PQ and H2O2 also significantly enhanced expression of intracellular superoxide dismutase (SOD) and catalase (CAT) activities in the first 48 h. However, the response extent was different. PQ increased mainly ligninolytic enzymes, whereas H2O2 led to enhanced antioxidant enzymes. Concentration of phenolic compounds and formaldehyde (FA) increased with treatments, but the level of malondialdehyde (MDA) and H2O2 decreased with both treatments. The results indicate that exposure of the whiterot mycelia to PQ and H2O 2 promoted oxidative stress. However, the antioxidant systems of the fungal strain are sufficient to prevent oxidative stress under PQ and H 2O2 challenge. Exogenous reactive oxygen species (ROS), as an endogenous oxidative stress, may also be a useful substrate in microbial biodegradation of lignocellulose.