Huang Shu-shi, Chen De, Pelczar Patricia L, Vepachedu Venkata Ramana, Setlow Peter, Li Yong-qing
Department of Physics, East Carolina University, Greenville, NC 27858-4353, USA.
J Bacteriol. 2007 Jul;189(13):4681-7. doi: 10.1128/JB.00282-07. Epub 2007 Apr 27.
Pyridine-2,6-dicarboxylic acid (dipicolinic acid [DPA]) in a 1:1 chelate with calcium ion (Ca-DPA) comprises 5 to 15% of the dry weight of spores of Bacillus species. Ca-DPA is important in spore resistance to many environmental stresses and in spore stability, and Ca-DPA levels in spore populations can vary with spore species/strains, as well as with sporulation conditions. We have measured levels of Ca-DPA in large numbers of individual spores in populations of a variety of Bacillus species and strains by using microfluidic Raman tweezers, in which a single spore is trapped in a focused laser beam and its Ca-DPA is quantitated from the intensity of the Ca-DPA-specific band at 1,017 cm(-1) in Raman spectroscopy. Conclusions from these measurements include the following: (i) Ca-DPA concentrations in the spore core are >800 mM, well above Ca-DPA solubility; (ii) SpoVA proteins may be involved in Ca-DPA uptake in sporulation; and (iii) Ca-DPA levels differ significantly among individual spores in a population, but much of this variation could be due to variations in the sizes of individual spores.
吡啶 -2,6 - 二羧酸（二吡啶甲酸 [DPA]）与钙离子以1:1螯合形成的Ca - DPA占芽孢杆菌属孢子干重的5%至15%。Ca - DPA对于孢子抵抗多种环境压力以及孢子稳定性至关重要，并且孢子群体中的Ca - DPA水平会因孢子种类/菌株以及孢子形成条件而异。我们使用微流控拉曼镊子测量了多种芽孢杆菌属物种和菌株群体中大量单个孢子的Ca - DPA水平，在微流控拉曼镊子中，单个孢子被困在聚焦激光束中，其Ca - DPA通过拉曼光谱中1017 cm⁻¹处Ca - DPA特异性谱带的强度进行定量。这些测量得出的结论如下：（i）孢子核心中的Ca - DPA浓度>800 mM，远高于Ca - DPA的溶解度；（ii）SpoVA蛋白可能参与孢子形成过程中Ca - DPA的摄取；（iii）群体中单个孢子的Ca - DPA水平存在显著差异，但这种差异很大程度上可能是由于单个孢子大小的变化所致。
