In the present study, Dictyostelium discoideum AX2-R2 was grown on living bacteria Escherichia coli B/r in shake-flasks and in standard stirred tank bioreactors. The maximum cell densities of D. discoideum detected in shake-flasks and in bioreactors were almost identical with 1.3 x 10(7) and 1.4 x 10(7) ml(-1), respectively. More than 99% of the bacterial biomass was consumed in both cases. D. discoideum was cultivated in the presence of different porous supports with the aim of studying its growth in an immobilized state using living bacteria as substrate. For small scale, a shake-flask cultivation system with external loop was applied, while on a larger scale a bioreactor was coupled with an external loop of a glass column containing a fixed bed of the porous support. Under these conditions, the maximum cell density of immobilized D. discoideum cells was 5.8 x 10(7) ml(-1) on porous sintered glass (SIKUG 041) and 2.4 x 10(6) ml(-1) on silicone foam (ImmobaSil R), respectively. The success of the immobilization process was documented by scanning electron microscopy. (C) 2008 Elsevier Ltd. All rights reserved.