Solid-state culture of Geotrichum candidum and Penicillium camembertii on a glutamate and lactate based medium

An inhibitory effect of pH limited growth: at the end of the linear growth (oxygen limitation), inhibitory pH values were observed at the surface of the medium, even if it was not the case for the mean pH values. Since growth was limited by the alkaline pH at the surface of the gel, to account for this inhibition, an additional term has been introduced in the expression for the partial linking between consumption or production and growth. The diffusion coefficients for glutamate, lactate and ammonium have been also considered. Then, the concentration gradients for glutamate, lactate and ammonium have been calculated (second Fick law) and found to match with the experimental gradients.