An auxostat is a continuous culture device which, while in operation, uses feedback from a measurement taken on the growth chamber to control the media flow rate, maintaining the measurement at a constant. Auxo was the Greek goddess of spring growth, and as a prefix represents nutrients. However, the most typical auxostats are pH-auxostats , with feedback between the growth rate and a pH meter.

Other auxostats may measure oxygen tension, ethanol concentrations, and sugar concentrations