Two-phase model of the kinetics of growth of Rhizopus oligosporus in membrane culture

An empirical model was developed to describe a growth profile occurring in solid-state fermentation (SSF), namely that consisting of an initial period of rapid acceleration followed by an extended period of deceleration. This kinetic profile is not adequately described by the logistic model. The emp irical model is based on the concept of active and nonactive hyphal segment s. Exponential and deceleration growth phases are modeled. The model parame ters can be determined directly from the dry-weight profile and they depend on the growth medium present. The model suggests that, at the instant the culture enters the deceleration phase, there is a 71% to 86% decrease in th e number of actively extending hyphal tips and that, during the deceleratio n phase, there is an exponential decay in the number of active hyphal segme nts, with a first-order decay constant of 0.042 to 0.072 h(-1). (C) 2000 Jo hn Wiley & Sons, Inc.