title: Water behavior in bacterial spores by deuterium NMR spectroscopy.
abstract: Dormant bacterial spores are able to survive long periods of time without nutrients, withstand harsh environmental conditions, and germinate into metabolically active bacteria when conditions are favorable. Numerous factors influence this hardiness, including the spore structure and the presence of compounds to protect DNA from damage. It is known that the water content of the spore core plays a role in resistance to degradation, but the exact state of water inside the core is a subject of discussion. Two main theories present themselves: either the water in the spore core is mostly immobile and the core and its components are in a glassy state, or the core is a gel with mobile water around components which themselves have limited mobility. Using deuterium solid-state NMR experiments, we examine the nature of the water in the spore core. Our data show the presence of unbound water, bound water, and deuterated biomolecules that also contain labile deuterons. Deuterium-hydrogen exchange experiments show that most of these deuterons are inaccessible by external water. We believe that these unreachable deuterons are in a chemical bonding state that prevents exchange. Variable-temperature NMR results suggest that the spore core is more rigid than would be expected for a gel-like state. However, our rigid core interpretation may only apply to dried spores whereas a gel core may exist in aqueous suspension. Nonetheless, the gel core, if present, is inaccessible to external water.
authors.affiliation: Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma , 101 Stephenson Parkway, Norman, Oklahoma 73019, United States.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Friedline
authors.forename: Malcolm M
authors.initials: MM
authors.lastname: Zachariah
authors.forename: Karen
authors.initials: K
authors.lastname: Johnson
authors.forename: Kieth J
authors.initials: KJ
authors.lastname: Thomas
authors.forename: Amy N
authors.initials: AN
authors.lastname: Middaugh
authors.forename: Ravindranath
authors.initials: R
authors.lastname: Garimella
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Powell
authors.forename: Parag A
authors.initials: PA
authors.lastname: Vaishampayan
authors.forename: Charles V
authors.initials: CV
authors.lastname: Rice
mesh_terms: D000818:Animals; D001412:Bacillus subtilis; D002417:Cattle; D003903:Deuterium / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013171:Spores, Bacterial / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D012710:Serum Albumin, Bovine; D006859:Hydrogen; D003903:Deuterium