Massey University, School of Engineering and Advanced Technology, North Shore City, Auckland, New Zealand.
Benef Microbes. 2011 Jun;2(2):129-38. doi: 10.3920/BM2011.0007.
The objective of the study was to design and produce calcium alginate beads that can deliver immobilised Lactobacillus reuteri DPC16 to a target site of the colon in the gastrointestinal (GI) tract. In this study, several factors that might affect the effectiveness of calcium alginate gel beads entrapping L. reuteri DPC16 cells were investigated. An in vitro GI tract model was used to simulate the pH variation and the existence of enzymes. Firstly, by varying the concentration of alginate at a constant concentration of CaCl2 the survival of immobilised DPC16 cells in simulated gastric fluid (SGF) was observed; secondly, the physical stability of calcium alginate beads containing skim milk during sequential incubation in the GI fluids was observed using optimal concentrations of alginate; finally, the survival of DPC16 cells immobilised within alginate beads containing skim milk were compared when the beads were incubated for different times during sequential exposure to the simulated fluids. The results demonstrated that non-encapsulated DPC16 cells were sensitive to an acidic environment, and no viable cells were detected after 90 min exposure in SGF (pH 1.2). With the protection of calcium alginate gel, the survival rate of immobilised DPC16 cells was slightly improved. An alginate concentration of 4% (w/v) was the most effective of those tested, but due to the irregular shape it formed, an alginate concentration of 3% (w/v) was used in further investigations. When skim milk (8% (w/v)) was added to the alginate solution, the cell survival was improved markedly. The optimal concentration of calcium chloride was 0.3 M, because the beads maintained their integrity in SGF and simulated intestinal fluid while disintegrating in simulated colonic fluid. The beads made from 3% alginate, 8% skim milk and 0.3 M CaCl2 proved to be an effective delivery and release system for DPC16 cells.
本研究旨在设计并制备可将固定化罗伊氏乳杆菌 DPC16 递送至胃肠道（GI）中结肠靶向部位的海藻酸钠珠。在本研究中，研究了可能影响包埋罗伊氏乳杆菌 DPC16 细胞的海藻酸钠凝胶珠有效性的几个因素。使用体外 GI 道模型模拟 pH 值变化和酶的存在。首先，通过在固定化 DPC16 细胞在模拟胃液（SGF）中的生存能力不变的情况下改变海藻酸钠的浓度，观察到了这一点；其次，使用优化的海藻酸钠浓度观察含有脱脂乳的海藻酸钠珠在 GI 液中连续孵育时的物理稳定性；最后，比较了含有脱脂乳的海藻酸钠珠中固定化 DPC16 细胞在连续暴露于模拟液时不同孵育时间的生存能力。结果表明，未包封的 DPC16 细胞对酸性环境敏感，在 SGF（pH 1.2）中暴露 90 分钟后，检测不到存活细胞。在海藻酸钠凝胶的保护下，固定化 DPC16 细胞的存活率略有提高。测试的海藻酸钠浓度中，4%（w/v）的效果最佳，但由于其形成的不规则形状，在进一步的研究中使用了 3%（w/v）的海藻酸钠浓度。当向海藻酸钠溶液中添加脱脂乳（8%（w/v））时，细胞存活率显著提高。最佳氯化钙浓度为 0.3 M，因为珠粒在 SGF 和模拟肠液中保持完整，而在模拟结肠液中则崩解。由 3%海藻酸钠、8%脱脂乳和 0.3 M CaCl2 制成的珠粒被证明是 DPC16 细胞的有效递药和释放系统。
