Influence of Growth and High Mould Concentration on the Pressure Drop in Solid State Fermentations

Aspergillus niger was grown on Amberlite IRA-900 imbibed with a solution containing high concentrations of sucrose (S_i = 100, 200, 300 and 400 g/litre) in static aerated fermentors. Growth was followed in dry biomass, biomass protein, CO₂ production and pressure drop (DP). The DP allowed the monitoring of germination, vegetative growth, limitation and the onset of sporulation for the four concentrations of sucrose studied. Concentrations up to 103 mg dry biomass/g dry support were obtained with S_i = 400 g/litre and these reduced the relative intrinsic permeability to 0·0125. Under this condition the mould occupies 34% of the free space. DP increase was related to CO₂ production.