Figure 1

Principle concepts of high cell density cultivation by the substrate limited fed-batch cultivation in a bioreactor (a), and by the novel enzyme controlled substrate auto-delivery system (b). Designations: (1) substrate reservoir, (2) control system for supply of the substrate with a pump in the standard bioreactor or with a specific concentration of an enzyme in the novel auto-delivery system, (3) liquid cell culture medium. A typical fed-batch process often starts with a batch phase which is characterised by a high initial glucose concentration which steadily decreases (a). In difference, in the novel method (b) the glucose level increases in the first phase due to the glucoamylase function and low consumption by the low number of cells. In both cases (a and b) the glucose concentration is very low after the initial batch phase. The biomass increase over the time is controlled either by the pump (a), or by the enzyme (b).