The production process for recombinant proteins substantially influences the final product performance. Fermentation development implies therefore massive expenditures. Concrete methods were developed which can be used for identification of optimal fermentation regimes under minimized use of resources. Online data from standard equipment used in bioreactors were partially model based investigated. For simple and reliable control of optimal fermentation trajectories, a temperature difference based method was established. Additionally, a new method for mass transfer studies during running fermentations was proposed. Based on these data, procedures for bioreactor characterization and improvements on the bioreactor setup were implemented.