The design of biological systems for biotechnological purposes employs strategies aimed at optimizing specific tasks. This approach is based on enhancing certain biological functions while reducing other capacities that are not required or that could be detrimental to the desired objective. A highly optimized cell factory would be expected to have only the capacity for reproduction and for performing the expected task. Such a hypothetical organism would be considered a minimal cell. At present, numerous research groups in academia and industry are exploring the theoretical and practical implications of constructing and using minimal cells and are providing valuable fundamental insights into the characteristics of minimal genomes, leading to an understanding of the essential gene set. In addition, research in this field is providing valuable information on the physiology of minimal cells and their utilization as a biological chassis to which useful biotechnological functions can be added.