Throughput, High-Intensity Fed-Batch Cultivation

Medium-Throughput, High-Intensity Fed-Batch Cultivation 

High growth rates in the fermenter thwart good product yield also for another reason. In highly developed production strains, the metabolic carbon flux toward the product of interest is deregulated and largely released from repressive mechanisms. In consequence, carbon source limitation affects product formation less severely than biomass formation and relatively more carbon will end up in the 

Biomass consumes the carbon substrate not only for reproduction but also for keeping itself in a viable state. The maintenance demand of a bacterial culture is defined as the carbon source requirements for purposes other than growth and product formation. The maintenance parameter can be determined by plotting the carbon source uptake rates during continuous fermentation runs at different dilution rates as a function of the growth rates and linear extrapolation to growth rate jW = 0 h . The y-intercept will then provide the maintenance parameter. 

To reduce the very high maintenance demand of the riboflavin-overproducing B. subtilis strain 1012 pRF93 a cydBC knockout mutant was constructed [243]. 

The gene product of cydB is the cytochrome bd oxidase subunit 11, whereas cydC together with cydD encodes an ABC transporter required for expression of cytochrome bd. From the various terminal oxidases of the branched Bacillus 

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