Fed-batch fermentation is a cultivation mode in which one or more medium components are added during growth while culture broth is retained until harvest. The initial charge establishes the starting volume and nutrient environment; the feed then changes substrate availability, osmolarity, volume, and dilution of soluble products ^[1]. Feed profiles may be constant, exponential, pulse-based, or adjusted from measurements such as dissolved oxygen, respiratory activity, residual substrate, or biomass estimates ^[2]. Deliberate limitation of a carbon or nitrogen source can restrain overflow metabolism and redirect cellular resources toward biomass, recombinant protein, organic acids, or secondary metabolites ^[1][3]. Because the working volume rises, the process also changes oxygen-transfer demand, mixing time, heat removal, and final product concentration ^[2][4]. A fed-batch run therefore requires coordinated decisions about feed composition, pump accuracy, addition timing, antifoam, pH control, and the harvest endpoint. The feed can also be stopped or redirected when the culture reaches a defined physiological state ^[5].