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Proceedings Paper

Magnetic resonance tells microbiology where to go; bacterial teichoic acid protects liquid water at sub-zero temperatures
Author(s): Charles V. Rice; Jason R. Wickham; Margaret A. Eastman; William Harrison; Mark P. Pereira; Eric D. Brown
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Paper Abstract

Numerous chemical additives lower the freezing point of water, but life at sub-zero temperatures is sustained by a limited number of biological cryoprotectants. Antifreeze proteins in fish, plants, and insects provide protection to a few degrees below freezing. Microbes have been found to survive at even lower temperatures, although, with a few exceptions, antifreeze proteins are missing. Survival has been attributed to external factors, such as high salt concentration (brine veins) and adhesion to particulates or ice crystal defects. Teichoic acid is a phosphodiester polymer ubiquitous in Gram positive bacteria, composing 50% of the mass of the bacterial cell wall and excreted into the extracellular space of biofilm communities. We have found that when bound to the peptidoglycan cell wall (wall teichoic acid) or as a free molecule (lipoteichoic acid), teichoic acid is surrounded by liquid water at temperatures significantly below freezing. Using solid-state NMR, we are unable to collect 31P CPMAS spectra for frozen solutions of lipoteichoic acid at temperatures above -60 °C. For wall teichoic acid in D2O, signals are not seen above -30 °C. These results can be explained by the presence of liquid water, which permits rapid molecular motion to remove 1H/31P dipolar coupling. 2H quadrupole echo NMR spectroscopy reveals that both liquid and solid water are present. We suggest that teichoic acids could provide a shell of liquid water around biofilms and planktonic bacteria, removing the need for brine veins to prevent bacterial freezing.

Paper Details

Date Published: 28 August 2008
PDF: 10 pages
Proc. SPIE 7097, Instruments, Methods, and Missions for Astrobiology XI, 70970O (28 August 2008); doi: 10.1117/12.800899
Show Author Affiliations
Charles V. Rice, Univ. of Oklahoma (United States)
Jason R. Wickham, Univ. of Oklahoma (United States)
Margaret A. Eastman, Oklahoma State Univ. (United States)
William Harrison, Univ. of Oklahoma (United States)
Mark P. Pereira, McMaster Univ. (Canada)
Eric D. Brown, McMaster Univ. (Canada)

Published in SPIE Proceedings Vol. 7097:
Instruments, Methods, and Missions for Astrobiology XI
Richard B. Hoover; Gilbert Victor Levin; Alexei Yu. Rozanov; Paul C.W. Davies, Editor(s)

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