Complexity and heterogeneity of microenvironments in immobilised systems

Influence of immobilization parameters on growth and lactic acid production by Streptococcus thermophilus and Lactobacillus bulgaricus co-immobilized in calcium alginate gel beads

“…It is not surprising to observe different lactic acid production when using different types of alginate, since alginate is a generic name for a range of substances with a wide variety of chemical compositions (e.g. guluronic acid/mannuronic acid ratio) which nevertheless exhibit similar physical properties (Nava Saucedo et al 1996).…”

“…Among the different reasons that can explain the observations above, mechanical internal forces, exopolysaccharides production by the lactic immobilized colonies and differences in calcium concentration inside the beads worth mentioned (Nava Saucedo et al 1996). Gel beads are heterogeneous structures presenting different domains of organization that can affect the behavior of entrapped biological materials (Garbayo et al 2002, Smidsrod & Skjak-Braek 1991.…”

How to build an adapted and bioactive cell microenvironment? A chemical interaction study of the structure of Ca‐alginate matrices and their repercussion on confined cells

“…Despite the complexity of the gelation process and the apparent stochastic nature of this phenomenon, gel beads used to immobilize or encapsulate cells are well‐structured macromolecular constructions. These supports present oriented and regular geometric structures throughout the gel network 10, 17. Consequently, characteristics such as bead cohesion, bead porosity, gel density, etc., are closely linked to the gel molecular structures.…”

“…Previous work performed in our laboratory9–13 with Ca‐alginate gel beads as supports for carrying cells has shown the importance of the matrix structure. The interactions existing between the alginate matrix and the embedded cells play a major role in their morphological and physiological behavior.…”

“…Even if biopolymers used for the confinement possess the same monomeric elements, they adopt different three‐dimensional arrangements during gelation. The gel properties of the matrix are largely due to these arrangements 9, 10, 16. These spatial designs may affect the behavior of the cell wall‐membrane system because of interactions with cell specific receptors giving rise, for example, to a significant modification of the cell permeability.…”