Abstract: A fermenting device for culturing aerobic microorganisms equipped with a plurality of stirrer-agitators also includes a preferably conical baffle screen which is open at the top and the bottom and is spaced from the walls of the fermentor device, and is disposed between each agitator for guiding air dispersed by one agitator into the space under the next agitator for redispersion thereby. Suitably an annular guide member is disposed along the interior walls of the fermentor and under the baffle screen to improve the efficacy of the redispersion. The aerobic fermentation process involves the dispersing of air introduced into the fermentor by a rotated agitator and then conducting the dispersed air by a baffle screen and optional annular guide member to a next agitator for redispersion.