A Circulation Flow Model and the Over-All Respiration Rate in Submerged Mold Culture

Abstract

A circulation flow model in which macro-mixing of liquid bulk and micro-mixing around mycelia are taken into consideration has been proposed for a submerged culture of filamentous mold in a stirred fermenter. In this model, the circulation time distribution of liquid is considered as a macro-mixing, and the degree of micro-mixing is represented by a volume of segregated liquid around the unit mass of mycelia.
The circulation time distribution in a mycelial suspension of Penicillium chrysogenum was measured with a magnetic particle tracer, and the distribution was found to be represented by the logarithmic normal-probability distribution. The volume of segregated liquid around the mycelia was calculated from this circulation time distribution and the over-all specific respiration rate. The volume thus calculated was independent of the mycelial concentration over 6 g/l, while the volume was increased as the power consumption increased.