Robust oxygen supply by controlled addition of hydrogen peroxide to microbial cultures

Abstract

The supply of oxygen can be improved by the direct addition of hydrogen peroxide to cultures of aerobic microbes expressing suf®cient amounts of catalase. This is of special interest if normal aeration has to be kept low, for instance, in order to minimize evaporation of volatile compounds (either substrates or products) or to minimize foaming. Also, if the mechanical power input to the bioreactor is or has to be limited, addition of hydrogen peroxide may be useful.The appropriate dosage of hydrogen peroxide can be simply determined by a controller of the oxygen partial pressure or of the oxygen content in the exhaust gas 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 controller disturbances. This approach proved to be very robust and reliable.

Use of n-hexadecane as an oxygen vector to improve Phaffia rhodozyma growth and carotenoid production in shake-flask cultures

“…To overcome oxygen limitation by increasing the stirrer speed and the aeration rate may lead to excessive power consumption and foam formation in the reactor, which is neither effective nor economical. One alternative approach is to generate oxygen chemically by introducing hydrogen peroxide to the medium, in which hydrogen peroxide will be converted to liquid oxygen by catalase inside the cells (Schlegel 1997; Sonnleitner and Hahnemann 1997). However, this approach may also necessitate simultaneous addition of catalase if the cells cannot produce sufficient catalase.…”

High hydrogen peroxide concentration in the feed-zone affects bioreactor cell productivity with liquid phase oxygen supply strategy

“…(7,8) were solved analytically to obtain concentration of tracer in the bulk of the bioreactor-zone at different times. The experimental data was acquired from impulse tracer study, in which impulse of glucose was injected to the bioreactor feed-zone and concentration of tracer in bulk of the bioreactor-zone was measured at different times.…”

“…But, use of a dilute H 2 O 2 solution causes undesirable effects such as dilution of culture in batch or in fed batch mode or significant modification of dilution rate and effective feed concentration in chemostat mode [8]. Therefore, use of a concentrated solution (30% w/v, 8.8 M) is preferred [5,6].…”

“…While employing LPOS, usually, a diluted or a concentrated solution of H 2 O 2 is pumped to the bioreactor in continuous mode [6,7], pulse mode [5] or with proportional-integral control of partial pressure of oxygen in the bioreactor [8]. But, use of a dilute H 2 O 2 solution causes undesirable effects such as dilution of culture in batch or in fed batch mode or significant modification of dilution rate and effective feed concentration in chemostat mode [8].…”