(eng): Two different approaches for adaptive control designare investigated and compared from a user's point of view. The first one is an application of the Matlab toolbox routine Designer, and the second approach is basedd on the commonly used adaptive linearizing control design method. The continuous aerobic fermentation of Saccharomyeces cerevisiae is taken as an object for control. The control task is the stabilization of ethanol productionat a previously set low value of concentration.