An immobilized cell bioreactor is a reaction vessel containing cells retained through attachment, entrapment, aggregation, or physical confinement. The retained cells remain metabolically active and can show physiological states associated with their immobilized organization ^[1]. A carrier supplies the physical structure for retention, and its arrangement affects contact between cells and the surrounding liquid ^[2]. Gel entrapment confines cells within a hydrated polymer network through which dissolved substrates and products can move ^[3]. Viable immobilized cells sustain intracellular enzyme systems while exchanging nutrients and metabolites with the medium. Fluid flow and diffusion connect the bulk liquid to the retained biomass, producing local concentration gradients when reaction outpaces transport. The reactor therefore contains interacting cellular, support, and liquid phases throughout the biochemical conversion ^[4].