PubMed · 5951484
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F L Soper. 1966. Smallpox--world changes and implications for eradication.. https://doi.org/10.2105/ajph.56.10.1652
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Maintaining the viability of lactic acid bacteria during dehydration and subsequent storage remains a significant challenge. Here, we employed single-cell RNA sequencing to reveal the heterogeneous stress responses of Lactobacillus delbrueckii subsp. bulgaricus, identifying seven distinct transcriptional clusters across the liquid culture, freeze-drying, and storage phases. The dominant clusters in the freeze-drying and storage were not completely consistent, showing significant functional differentiation. Genomic stability may be important for survival during freeze-drying and storage, while intracellular energy homeostasis appears important for viability during storage. The magnesium transporter mgtB was highly expressed in clusters tolerant to freeze-drying and storage, suggesting a critical role for Mg2+ homeostasis. Further experimental validation confirmed that Mg2+ treatment significantly bolstered stress resistance, increasing immediate post-freeze-drying survival by over 2-fold (up to 92.90%) and post-storage survival by over 5-fold (up to 5.98%). Proteomic data indicated that Mg2+ supplementation correlated with the maintenance of several biological functions potentially relevant to bacterial survival during freeze-drying and storage, including DNA repair, translation, and central carbon metabolism. These findings provide a map of microbial stress resistance through population heterogeneity and offer a potential strategy that may be adapted for enhancing the stability of other industrial lactic acid bacteria products.
PURPOSE: An efficient freeze-drying cycle for recombinant human interleukin-1 receptor antagonist (rhIL-1ra) formulations, which contained glycine and sucrose as excipients, was developed. METHODS: Development was based on characterizing the frozen formulations by thermal analysis and by examining the effect of various lyophilization process parameters on the sublimation rate of ice. RESULTS: Thermal analysis showed that the metastable glass of glycine in frozen formulation could be devitrified by slowly warming the frozen product to -15 degrees C. During drying, the sublimation rate of ice was increased as a linear function of the difference between the vapor pressure of ice at the product temperature (PO) and the chamber pressure (PC). Therefore, the product temperature (Tp) was maintained as high as possible at temperatures below Tg' of the formulation, in order to maximize the PO without allowing the collapse of cake. Although various combinations of shelf temperatures and chamber pressures could be used to obtain the same Tp, the combination of higher shelf temperature and lower chamber pressure was used to maximize sublimation rate. CONCLUSIONS: A single-step drying cycle was developed to take advantage of these observations. The shelf temperature was set for the secondary drying and the product temperature during primary drying was maintained below Tg' by adjusting the chamber pressure. As the sublimation completed, the product temperature increased naturally to the shelf temperature for the secondary drying. This process resulted in successful drying of 1 ml of rhIL-1ra formulation to 0.4% moisture content within 6 hours.
The effect of storage conditions on the serological activity of two strains of potato virus S (PVS), Andean and the ordinary, was studied by ELISA. Virus purificates, infected leaves and their homogenates, stored in lyophilized, frozen and dissolved form at various temperatures were tested. Virus purificates were most stable in lyophilized form, their activity decreased after 9 months only by 20-30%. Also non-purified virus was most stable as a lyophilized leaf homogenate, its activity decreased after 12 months by 30%. When lyophilized leaves were stored, the virus activity dropped after 12 months by 45%. Both the Andean and the ordinary strain of PVS behaved similarly during storage under the conditions tested.