High-cell-density cultivation of microorganisms

High-cell-density cultivation (HCDC) is required to improve microbial bioma ss and product formation substantially. An overview of HCDC is given for mi croorganisms including bacteria, archae and eukarya (yeasts). Problems enco untered by HCDC and their possible solutions are discussed. Improvements of strains? different types of bioreactors and cultivation strategies for suc cessful HCDC are described. Stirred-tank reactors with and without cell ret ention, a dialysis-membrane reactor, a gas-lift reactor and a membrane cycl one reactor used for HCDC are outlined. Recently modified traditional feedi ng strategies and new ones are included, in particular those for unlimited growth to very dense cultures. Emphasis is placed on robust fermentation co ntrol because of the growing industrial interest in this field. Therefore, developments in the application of multivariate statistical control, artifi cial neural networks, fuzzy control and knowledge-based supervision (expert systems) are summarized. Recent advances using Escherichia coli - the pion eer organism for HCDC - are outlined.