Modelling the sporulation dynamics of arbuscular mycorrhizal fungi in monoxenic culture

Spore production of arbuscular mycorrhizal fungi is important in inoculum production, and monoxenic culture is a promising way to produce large amounts of contaminant-free inoculum. Mass production of spores is therefore essential and mathematical models useful as descriptive and predictive tools of sporulation dynamics. We followed the sporulation dynamics of three Glomus strains i.e. G. intraradices, G. proliferum and G. caledonium, cultured monoxenically on a nutrient agar medium containing macro- and microelements, vitamins and sucrose. Three models (Schnute, logistic, and Gompertz) were fitted to the data and compared in order to select the most adequate model. The Schnute, model was the reference against which the two other models were tested. For all three Glomus strains examined, the sporulation dynamics followed a sigmoidal curve with a lag, a log, and a plateau phase. Visually, all three models fitted the data very well, with R-2 values ranging from 0.9703 to 0.9995. They thus appeared adequate for describing the temporal dynamics of spore production. In most cases the Gompertz model described sporulation as accurately as the Schnute model, but the performance of the logistic model was seldom as good. The Gompertz model is thus convenient for modelling the sporulation dynamics of Glomus strains grown in a well-defined nutrient agar medium. As such, its use may facilitate and help improve exploitation of monoxenic culture systems.