Many antibiotic fermentations are sensitive to high concentrations of their own product possibly due to product regulation and toxicity mechanisms. In this paper we discuss the feasibility of using affinity adsorption with biospecific ligands for in situ product removal to alleviate this problem. The concept of using whole cells containing the biospecific ligands is demonstrated in the case of thienamycin fermentation using whole cells of Bacillus stearothermophilus and immobilized β-lactamase. It is observed that thienamycin production continues for an extended period of time.