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Glass formation and dormancy in bacterial spores
Author(s) -
Ablett Steve,
Darke Arthur H.,
Lillford Peter J.,
Martin David R.
Publication year - 1999
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1046/j.1365-2621.1999.00240.x
Subject(s) - spore , differential scanning calorimetry , bacillus subtilis , dormancy , germination , endospore , dipicolinic acid , solid state nuclear magnetic resonance , protoplast , amorphous solid , nuclear magnetic resonance spectroscopy , chemistry , chemical engineering , biology , botany , nuclear magnetic resonance , bacteria , crystallography , thermodynamics , stereochemistry , physics , genetics , engineering
Summary Differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) techniques were used to obtain evidence whether a glassy state exists within fully hydrated dormant Bacillus subtilis spores. DSC thermograms of hydrated dormant spores contained two major transitions; one at ∼60 °C assigned to be associated with the initial ‘activation’ stage for germination, and the other at ∼120 °C assigned to be associated with the ‘inactivation’ process (i.e. killing of the spores). The peak at ∼60 °C had characteristics which were all consistent with at least some region of the compartmentalised structure of fully hydrated dormant spores being in a glassy state. Solid (CPMAS) and liquid state (SPMAS) mobility resolved 13 C NMR spectroscopy studies on the calcium dipicolinic acid (CaDPA) resonances, which are only present in the central protoplast of bacterial spores, showed it to be present in an amorphous solid‐like environment. The DSC and NMR results were both found to be consistent with the hypothesis that the dormancy of bacterial spores is due to at least the central protoplast region being maintained in a low moisture content glassy state.