Review Calcium Alginate Beads as Immobilizing Matrix of Functional Cells: Extrusion Dripping Method, Characteristics, and Application

Abstract

Abstract Sodium alginate is the polymer matrix most commonly used for the immobilization of cells, enzymes, and microalgae for various purposes. One of the bead immobilization preparations is the droplet extrusion method in which CaCl2 is the adsorbent. However, the use of CaCl2, which is a cross-linking agent, can increase alginate susceptibility. Therefore, this review aims to provide an overview of the application of immobilized cells in the form of reused beads for the production of biohydrogen and bioethanol, as well as beads for removing heavy metals from wastewater, and removing potassium from vinasse. Meanwhile, the immobilized cells used were cow dung, Saccharomyces cerevisiae (S. cerevisiae), and D. subspicatus. All reported applications have shown that the initial bead shape of the drip extrusion method was spherical. However, over time the alginate beads become eroded due to repeated use. Round beads occurred when using 2% alginate concentration and the performance was optimum compared to 1% and 2% of alginate concentrations even though the cross-linked concentrations varied.