BUBBLE FREE GASEOUS TRANSFER IN BIOREACTORS USING PERFLUOROCARBONS

In this work the concept of bubble-free oxygenation that was able to e nsure oxygen supply and carbon dioxide extraction for a chemostat cult ure of Escherichia coli was experimentally demonstrated. It was operat ed at the dilution rate of 0.275 h(-1) under atmospheric pressure and at 35.5 degrees C. Foralkyl, a commercial perfluorocarbon, added in th e influent medium under emulsified form and at 50% volumic fraction, w as able to provide 0.17 g O-2/l/h and extract 0.23 g CO2/l/h for a cul ture at 0.74 g/l of biomass. This oxygen supply was close to the maxim um oxygenation Foralkyl was theoretically able to provide at this pres sure when imposing a minimum oxygen concentration of 1 mg/l in the wat er phase. The quantification of transfer was not done from a direct me asurement of oxygen transfer rates because conventional oxygen concent ration measurement by membrane polarographic probe in an emulsion was not judged reliable. This evaluation was done by referring to conventi onal aerated culture whose measurable parameters (biomass and product concentrations) were found unaffected when shifting to the novel oxyge nation device.