Effect of periodically dynamic changes of air on cellulase production in solid-state fermentation

In solid-state fermentation, the shear forces caused by rotation and agitation damage or disrupt fungal mycelia and reduce the porosity of the substrates, while the forces led by dynamic changes of air (including air pressure pulsation and internal circulation) are not shearing but normal. The substrates, which are more effectively utilized in the solid-state culture with periodically dynamic changes of air (dynamic culture), are looser and provide more room for fungal propagation than in the static culture. The maximum average filter paper enzyme activity (FPA) in the dynamic culture with the fermentation period 60 h is 20.4 IU/g at a bed height of 9.0 cm while the maximum average FPA is 10.8 IU/g in the static culture with the fermentation period 84 h.