Despite several decades of research into encapsulation of bacteria, most of the proposed technologies are in the form of immobilized cultures. In this work, sporopollenin exine capsules (SECs) opened, using silica particles which act as pressing micro-probes, and loaded with Lactobacillus casei (L. casei) cells, are described for the first time. The proposed encapsulation provided ≈30× higher encapsulation yield (30.87%), compared to direct compression of SECs (0.99%). Encapsulated L. casei cells show 1.21- and 2.25-folds higher viability compared to free cells, in in vitro simulated fasted and fed media representing the human gastrointestinal (GI) tract, respectively. Encapsulated L. casei can proliferate inside the SECs, generating enough pressure to cause the SECs to burst and release the viable and metabolically active cells. The noticeable difference with the application of the SECs as a means of encapsulation is that the SECs may act as a bioreactor and provide time for the encapsulated cells to multiply thousands of times before being released, following the SEC's burst. The unique advantages of SECs alongside the proposed encapsulation method, demonstrates the potential application of SECs as delivery system of probiotics to the distal part of the human GI tract.
Keywords: flow cytometry; lactobacillus casei; microencapsulation; mrs plate count; probiotics; scanning electron microscope; sporopollenin.
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