Gel phase in hydrated calcium dipicolinate Academic Article uri icon

abstract

  • The mineralization of dipicolinic acid (DPA) molecules in bacterial spore cores with Ca2+ ions to form Ca-DPA is critical to the wet-heat resistance of spores. This resistance to wet-heat also depends on the physical properties of water and DPA in the hydrated Ca-DPA-rich protoplasm. Using reactive molecular dynamics simulations, we have determined the phase diagram of hydrated Ca-DPA as a function of temperature and water concentration, which shows the existence of a gel phase along with distinct solid-gel and gel-liquid phase transitions. Simulations reveal monotonically decreasing solid-gel-liquid transition temperatures with increasing hydration, which explains the experimental trend of wet-heat resistance of bacterial spores. Our observation of different phases of water also reconciles previous conflicting experimental findings on the state of water in bacterial spores. Further comparison with an unmineralized hydrated DPA system allows us to quantify the importance of Ca mineralization in decreasing diffusivity and increasing the heat resistance of the spore.

published proceedings

  • APPLIED PHYSICS LETTERS

altmetric score

  • 14.58

author list (cited authors)

  • Rajak, P., Mishra, A., Sheng, C., Tiwari, S., Krishnamoorthy, A., Kalia, R. K., Nakano, A., & Vashishta, P.

citation count

  • 4

complete list of authors

  • Rajak, Pankaj||Mishra, Ankit||Sheng, Chunyang||Tiwari, Subodh||Krishnamoorthy, Aravind||Kalia, Rajiv K||Nakano, Aiichiro||Vashishta, Priya

publication date

  • November 2017