Ion Exchange Kinetics of Natural Ionic Nanoreservoirs: Bacillus subtilis Spores
S. Kazakov, E. Bonvouloir, I. Gazaryan and K. Miller
Pace University, US
bacillus spores, ionic reservoir, time-resolved pH measurements
The structure of Bacillus spores, particularly, the properties of the spore cortex, a peptidoglycan cross-linked polymer (negative net charge, high level of mobile ions, high degree of freedom of ions movement, ability to change volume in response to ionic changes or water content), allow one to consider a spore as a natural ionic reservoir. In the present work the ability of Bacillus subtilis spores to accumulate and release ions and to expand or contract in response to external conditions was examined. Changes in ion concentrations in the exterior to the spores were measured with time. This kinetic approach is also an analytical tool to study the mechanical and electrochemical behavior of bacterial spores. Potentiometric titration curves for Bacillus subtilis spores were obtained to show that each spore behaves like almost infinite ionic reservoir capable of accumulating billions of protons. The parameters of protonation/deprotonation kinetics were extracted from the time-resolved measurements of pH equilibration in spores’ suspensions for different conditions effecting on spore germination (extreme pH, temperature, and nutrients). The spore size and shape were monitored using dynamic light scattering and phase contrast optical microscopy. The results are of great potential for new methods of spore detection and identification and for understanding the phenomenological and molecular mechanisms of germination and sporulation of the Bacillus bacteria.
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Nanotech 2006 Conference Program Abstract