The dissolved oxygen concentration (DO) is an important variable in aerobic fermentations. Precise control of the DO is critical in fermentation processes for the investigation of the best conditions for secondary product formation. Oxygen limitation conditions have been known to enhance the synthesis of secondary products. An adaptive pole placement control that maintains a constant sheer environment is applied to Bacillus subtilis fermentation for the production of beta-lactamase. AutoRegressive eXogeneous (ARX) input models are used for the control, and supervision and coordination techniques are applied to improve the control performance. The effect of DO level on the productivity of beta-lactamase under oxygen-limited conditions is assessed.