DYNAMIC MODELING OF IMMOBILIZED NITROSOMONAS-EUROPAEA - IMPLEMENTATION OF DIFFUSION LIMITATION OVER EXPANDING MICROCOLONIES

A dynamic model (pseudohomogeneous growth model) describing growth and substrate consumption of immobilized Nitrosomonas europaea resulted i n predictions for consumption rates that were higher than experimental ly obtained data. This overestimation was caused by effects of diffusi on limitation over microcolonies. Diffusion limitation over microcolon ies has been integrated in the colony expansion model. In this model g rowth is implemented by expansion of colonies. Colonies breaking throu gh the gel surface cause release of bacteria into the surrounding medi um. Two options were considered for this release: either growth result ing in continuous leakage of single bacteria or eruption of entire col onies at once. In the latter case both macroscopic consumption rates a nd transient-stare biomass concentration profiles are described satisf actorily by the model. It is also shown that the results of the previo us experiments with Nitrobacter agilis can be described by the model a s well.