Patent ID: 8257961

Claim:
A mechanically-agitated fermenter, comprising: a) a vessel capable of holding a fermentation medium below a headspace, b) a mechanical agitator disposed within the vessel, c) a diffuser located within the vessel, d) a supply of substantially pure oxygen, the oxygen supply being in fluid communication with the diffuser, the oxygen supply being the only source of reactive gas, external to the vessel, that is connected to the diffuser, e) an analyzer for measuring configured to measure a concentration of oxygen in an exhaust line extending from the vessel headspace and in fluid communication with an exhaust vent and the analyzer, the analyzer being connected to an adjustable valve for controlling and adapted to control a flow of oxygen from the supply to the diffuser in response to an oxygen concentration in the exhaust line; and f) an exhaust vent that-directs adapted to direct gases from the head space exhaust line to an atmosphere outside the vessel.