Determination of the respiration kinetics for mycelial pellets of Phanerochaete chrysosporium.

In mycelial pellet cultures of white rot basidiomycete Phanerochaete chrysosporium, low oxygen concentration negatively affects the production of the extracellular lignin peroxidases and manganese perioxidases which are key components of the lignin-degrading system of this organism. To test the hypothesis that oxygen limitation in the pellets is responsible for this effect, oxygen microelectrodes were used to determine oxygen concentration gradients within the mycelial pellets of P. chrysosporium. Pellets were removed from oxygenated cultures, allowed to equilibrate with air, and probed with oxygen microelectrodes. The oxygen profiles were modelled assuming that O[sub 2] uptake follows a Michaelis-Menten relationship. The V[sub max] and K[sub m] values were used to predict respiration rates in air-flushed cultures, oxygen-flushed cultures, and cultures with large pellets. The predicted respiration rates were independently validated by experimentally measuring the evolution of carbon dioxide from whole cultures.