Encapsulation in Calcium Alginate Beads Regulates Growth, Release and Viability of Probiotic Bacteria Through...

Aims: Our aim was to evaluate calcium alginate beads as a physical cultivation platform for probiotic bacteria and investigate their effects on bacterial growth localization, release dynamics, and viability under different environmental conditions. Methods and Results: Calcium alginate beads were fabricated using sodium alginate at different concentrations (1.0-2.0%, w/v), and their structural stability, permeability, and pH resistance were assessed. Lacticaseibacillus paracasei was used as the primary model organism. Among the tested formulations, 2.0% alginate exhibited the lowest permeability (~40%) compared with 1.0% and 1.5% alginate (~60%) and maintained structural integrity under alkaline conditions (pH 11-12). Encapsulated L. paracasei proliferated predominantly within the bead matrix, while less than 1% of total bacteria were released into the surrounding medium during the first 12 h and approximately 8% released after 24 h. Encapsulation also maintained higher bacterial viability over 24-48 h compared with conventional liquid culture conditions. Encapsulated cells could be efficiently recovered using sodium citrate without marked loss of viability. In addition, encapsulation enabled the growth of Bifidobacterium animalis subsp. lactis under aerobic incubation conditions, suggesting the formation of locally protective microenvironments within the gel matrix. Conclusions: Calcium alginate beads function as controllable microenvironmental regulators that influence bacterial growth, release behavior, and long-term viability. These findings suggest that alginate-based encapsulation systems may provide a simple and scalable platform for controlled microbial cultivation and probiotic-related applications.