US Patent 7718405 Use of pure oxygen in viscous fermentation processes

A fermentation process uses substantially pure oxygen as the sole gas introduced into a fermentation vessel while fermentation reactions are active. The oxygen is introduced at multiple locations along the height of the vessel, and is preferably introduced in the vicinity of the blades of an impeller. The invention enhances the rate at which oxygen can be transferred to the fermentation medium, and is especially useful for fermentation media which become very viscous as the process continues. The invention can be used in the manufacture of viscous products such as xanthan gum, or other products having viscosities greater than about 100 cp.