ROBUST OXYGEN-SUPPLY BY CONTROLLED ADDITION OF HYDROGEN-PEROXIDE TO MICROBIAL CULTURES

The supply of oxygen can be improved by the direct addition of hydroge n peroxide to cultures of aerobic microbes expressing sufficient amoun ts of catalase. This is of special interest if normal aeration has to be kept low, for instance, in order to minimize evaporation of volatil e compounds (either substrates or products) or to minimize foaming. Al so, if the mechanical power input to the bioreactor is or has to be li mited, addition of hydrogen peroxide may be useful. The appropriate do sage of hydrogen peroxide can be simply determined by a controller of the oxygen partial pressure or of the oxygen content in the exhaust ga s using various control algorithms. The added hydrogen peroxide can be either a stabilized concentrate, e.g. 30%, or any dilute form of this . In high density cultures, Pseudomonas cells tolerated even harsh con troller disturbances. This approach proved to be very robust and relia ble.