Five cartridges with immobilized glucose oxydase, alcohol oxydase, pyranose oxydase, L-amino acid oxydase and L-lactate-2-monooxigenase, respectively, were integrated into a flow injection analysis (FIA) system and applied to the monitoring of medium components: glucose and ethanol during the cultivation of Saccharomyces cerevisiae, L-amino acids during the production of the fusion protein EcoRI::SPA by recombinant Escherichia coli, and lactate during the production of lactic acid by Lactobacillus salivarius var. salivarius. The developed enzyme cartridge-FIA systems show a reproducible operation, low pressure drop and long-range enzyme activities and are well suited for on-line monitoring of microbial cultivation processes.