The effect of the dissolved oxygen concentration on the production of lignin peroxidase and manganese peroxidase by Phanerochaete chrysosporium

The effect of the dissolved oxygen (D.O.) concentration on the production of lignolytic enzymes and isozyme distributions by Phanerochaete chrysosporium was studied in the immobilized reactor system. The oxygen levels significantly affected the production of lignin peroxidase (LiP) and manganese peroxidase (MnP), as well as that of H₂O₂. It is known that a high oxygen level is required to produce these enzymes. In this study, however, D.O. concentrations above a critical D.O. concentration (1.5 fold increase over the saturated concentration with air) inhibited LiP and MnP productions in the experiments when oxygen was continuously supplied. It is thought that a greater H₂O₂ accumulation seen with higher D.O. concentrations caused adverse effects on the LiP and MnP productions. On the other hand, with lower D.O. concentrations, H₂O₂ was not produced enough to stimulate either LiP or MnP production. To reduce excess H₂O₂ accumulation during culturing with a continuous supply of oxygen, a pulsed supply of oxygen was introduced.