Lahtinen S J, Ahokoski H, Reinikainen J P, Gueimonde M, Nurmi J, Ouwehand A C, Salminen S J
Functional Foods Forum, University of Turku, Finland.
Lett Appl Microbiol. 2008 Jun;46(6):693-8. doi: 10.1111/j.1472-765X.2008.02374.x. Epub 2008 Apr 28.
To assess the stability of 16S rRNA of viable but nonculturable (VBNC) probiotics during storage when compared with different attributes of viability.
Levels of RNA of the probiotic strains Bifidobacterium longum 46, B. longum 2C and B. animalis subsp. lactis Bb-12 were monitored during storage in fermented and nonfermented foods. Cells which gradually lost their culturability in fermented products retained high level of rRNA, whereas rRNA of acid-killed control cells decreased at faster rate. Furthermore, the viability of B. longum 2C was monitored during storage by measuring changes in reductase activity, cytoplasmic membrane integrity and esterase activity using a flow cytometer. All of the culture-independent viability assays suggested that the cells remained viable during storage. In nonfermented media, the observed losses in culturability were smaller, and the changes in cell counts were comparable with the changes in rRNA levels.
Viable but nonculturable probiotics maintain high levels of rRNA and retain properties of viable bacteria including reductase activity. Quantification of 16S rRNA complements culture-independent viability assays.
Culture-independent viability assays allow the detection of VBNC probiotics, and can be used parallel to conventional culture-dependent methods to obtain accurate information on probiotic viability.
与不同的生存能力属性相比，评估存活但不可培养（VBNC）益生菌的16S rRNA在储存期间的稳定性。
在发酵和未发酵食品储存期间，监测了长双歧杆菌46、长双歧杆菌2C和动物双歧杆菌乳亚种Bb-12的RNA水平。在发酵产品中逐渐丧失可培养性的细胞保留了高水平的rRNA，而酸灭活对照细胞的rRNA以更快的速度下降。此外，在储存期间通过使用流式细胞仪测量还原酶活性、细胞质膜完整性和酯酶活性的变化来监测长双歧杆菌2C的生存能力。所有非培养依赖性生存能力测定均表明细胞在储存期间保持存活。在未发酵培养基中，观察到的可培养性损失较小，细胞计数的变化与rRNA水平的变化相当。
存活但不可培养的益生菌维持高水平的rRNA，并保留包括还原酶活性在内的活细菌特性。16S rRNA的定量补充了非培养依赖性生存能力测定。
非培养依赖性生存能力测定能够检测VBNC益生菌，并且可以与传统的培养依赖性方法并行使用，以获得关于益生菌生存能力的准确信息。
