Huang, Shu-shiChen, DePelczar, Patricia L.Vepachedu, Venkata RamanaSetlow, PeterLi, Yong-Qing2011-03-022011-05-172011-03-022011-05-172007-07Journal of Bacteriology; 189:13 p. 4681-4687http://hdl.handle.net/10342/3281Pyridine-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. Originally published Journal of Bacteriology, Vol. 189, No. 13, July 2007en-USAuthor notified of opt-out rights by Cammie Jennings.Bacillus sporesCa-DPARaman spectroscopyArticlePMC191342610.1128/JB.00282-07