Department of Microbiology, Uppsala Biocenter, Swedish University of Agricultural Sciences, P.O. Box 7025, SE-750 07 Uppsala, Sweden.
Cryobiology. 2012 Jun;64(3):152-9. doi: 10.1016/j.cryobiol.2012.01.002. Epub 2012 Jan 15.
Freeze-drying of bacterial cells with retained viability and activity after storage requires appropriate formulation, i.e. mixing of physiologically adapted cell populations with suitable protective agents, and control of the freeze-drying process. Product manufacturing may alter the clinical effects of probiotics and it is essential to identify and understand possible factor co-dependencies during manufacturing. The physical solid-state behavior of the formulation and the freeze-drying parameters are critical for bacterial survival and thus process optimization is important, independent of strain. However, the maximum yield achievable is also strain-specific and strain survival is governed by e.g. medium, cell type, physiological state, excipients used, and process. The use of preferred compatible solutes for cross-protection of Lactobacilli during industrial manufacturing may be a natural step to introduce robustness, but knowledge is lacking on how compatible solutes, such as betaine, influence formulation properties and cell survival. This study characterized betaine formulations, with and without sucrose, and tested these with the model lactic acid bacteria Lactobacillus coryniformis Si3. Betaine alone did not act as a lyo-protectant and thus betaine import prior to freeze-drying should be avoided. Differences in protective agents were analyzed by calorimetry, which proved to be a suitable tool for evaluating the characteristics of the freeze-dried end products.
细菌细胞的冷冻干燥需要保留其活力和活性，这就需要合适的配方，即混合具有生理适应性的细胞群体与适当的保护剂，并控制冷冻干燥过程。产品制造可能会改变益生菌的临床效果，因此，在制造过程中识别和理解可能的因素相互依存关系是至关重要的。配方的物理固态行为和冷冻干燥参数对细菌的生存至关重要，因此，无论菌株如何，优化过程都很重要。然而，可达到的最高产量也是特定于菌株的，菌株的存活率取决于例如培养基、细胞类型、生理状态、使用的赋形剂和工艺。在工业制造过程中，使用优选的相容溶质来对乳杆菌进行交叉保护可能是引入稳健性的自然步骤，但对于相容溶质（如甜菜碱）如何影响配方特性和细胞存活率，我们的了解还很有限。本研究对含有和不含有蔗糖的甜菜碱配方进行了表征，并使用模型乳酸菌乳杆菌 Si3 对这些配方进行了测试。甜菜碱本身不能作为冷冻保护剂，因此应避免在冷冻干燥前导入甜菜碱。通过量热法分析了保护剂的差异，证明量热法是评估冷冻干燥最终产品特性的合适工具。
