Effect of Cation Influx on the Viability of Freeze-Dried Lactobacillus brevis WiKim0069

Abstract

Extension of the storage stability of freeze-dried lactic acid bacteria is important for industrialization. In this study, the effect of cation influx from soy powder, which contains high amounts of cations, as a cryoprotective agent on the viability of freeze-dried Lactobacillus brevis WiKim0069 was tested. Compared to that in the absence of the soy powder, bacterial viability was significantly higher in the presence of soy powder. Approximately 4.7% of L. brevis WiKim0069 survived in the absence of the protective agent, whereas 92.8% viability was observed in the presence of soy powder. However, when cations were removed from the soy powder by using ethylenediaminetetraacetic acid (EDTA) and a cationic resin filter, the viability of L. brevis WiKim0069 decreased to 22.9–24.7%. When the soy powder was treated with ethylene glycol tetraacetic acid, the viability was higher than when it was pretreated with EDTA and a cationic resin filter, suggesting that Mg2+ had a role in enhancing the viability of L. brevis WiKim0069. Cold adaptation at 10 °C prior to freeze-drying had a positive effect on the storage stability of freeze-dried L. brevis WiKim0069, with 60.6% viability after 56 days of storage. A decrease in the fluorescence polarization value indicated an increase in membrane fluidity, which regulates the activity of ion channels present in the cell membrane. Cold adaptation caused activation of the cation channels, resulting in increased intracellular influx of cations, i.e., Ca2+ and Mg2+. These results suggest that cold adaptation can be used to improve the storage stability of L. brevis WiKim0069.

Efficient Citrus (Citrus unshiu) Byproduct Extract-Based Approach forLactobacillus sakeiWiKim31 Shelf-Life Extension

“…Cold adaptation before freeze-drying has a positive effect on LAB cell viability. 32 Here, L. sakei WiKim31 cold adaptation treatment compared to the non-adapted cells increased the expression of exopolysaccharides (EPSs) in the cell wall ( Figure 2 ). In a similar study, cold adaptation was found to increase the surface-layer thickness of Lactobacillus brevis WiKim0069 cells by 26.7% compared with non-adapted cells.…”

“…sakei WiKim31 were observed and evaluated. Cold adaptation before freeze-drying has a positive effect on LAB cell viability . Here, L.…”

“…Particularly, cold adaptation can increase cation influx by activating cation channels. 32 Therefore, a mixture of SP and CP can be used as a cryoprotective agent to improve the viability of L. sakei WiKim31 by supplying each deficient cation.…”

“…Intracellular cations (Ca 2+ and Mg 2+ ) with cryoprotective effects can extend the shelf-life of freeze-dried LAB by minimizing the damage caused by osmotic pressure. Particularly, cold adaptation can increase cation influx by activating cation channels . Therefore, a mixture of SP and CP can be used as a cryoprotective agent to improve the viability of L.…”

Supercooling Pretreatment Improves the Shelf-Life of Freeze-Dried Leuconostoc mesenteroides WiKim32

“…Temperatures below the optimum temperature required for LAB growth result in the initiation of cold shock responses that improve LAB viability. These responses include upregulation of cold-related genes, production of cold-induced proteins, changes in fatty acid composition, and an increase in cation influx [ 10 - 13 ]. Cold-adapted cells eventually survive after the freeze-drying process.…”