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Appl. Environ. Microbiol., 10 1995, 3592-3597, Vol 61, No. 10
SB Leslie, E Israeli, B Lighthart, JH Crowe and LM Crowe
The microorganisms Escherichia coli DH5 alpha and Bacillus thuringiensis
HD-1 show an increased tolerance to freeze-drying when dried in the
presence of the disaccharides trehalose and sucrose. When the bacteria were
dried with 100 mM trehalose, 70% of the E. coli and 57% of the B.
thuringiensis organisms survived, compared with 56 and 44%, respectively,
when they were dried with sucrose. Only 8% of the E. coli and 14% of the B.
thuringiensis organisms survived drying without the sugars. Fourier
transform infrared spectroscopy was used to investigate the role of
membrane phase transitions in the survival of the organisms during drying
and rehydration. Both E. coli and B. thuringiensis showed an increase of 30
to 40 degrees C in the temperature of their phospholipid phase transition
when dried without the sugars, while phase transition temperatures of those
dried with the sugars remained near those of the hydrated cells. A Fourier
transform infrared spectroscopy microscope made it possible to investigate
the effects of drying on the protein structure in the intact cells. The
amide II peak shifts from 1,543 cm-1 in the hydrated cells to about 1,533
cm-1 in the cells dried without sugar. There is no shift in the amide II
peak when the cells are dried with trehalose or sucrose. We attribute the
increased survival to the sugars' ability to lower the membrane phase
transition temperature and to protect protein structure in the dry
state.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Trehalose and sucrose protect both membranes and proteins in intact bacteria during drying
Section of Molecular and Cellular Biology, University of California, Davis 95616, USA.
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