Cryoprotection from lipoteichoic acid

摘要

Numerous chemical additives lower the freezing point of water, but life at sub-zero temperatures issustained by a limited number of biological cryoprotectants. Antifreeze proteins in fish, plants, and insects provideprotection to a few degrees below freezing. Microbes have been found to survive at even lower temperatures, andwith a few exceptions, antifreeze proteins are missing. Survival has been attributed to external factors, such as thehigh salt concentration of brine veins and adhesion to particulates or ice crystal defects. We have discovered anendogenous cryoprotectant in the cell wall of bacteria, lipoteichoic acid biopolymers. Adding 1% LTA to bacteriacultures immediately prior to freezing provides 50% survival rate, similar to the results obtained with 1% glycerol.In the absence of an additive, bacterial survival is negligible as measured with the resazurin cell viability assay. Themode of action for LTA cryoprotection is unknown. With a molecular weight of 3-5 kDa, it is unlikely to enter thecell cytoplasm. Our observations suggest that teichoic acids could provide a shell of liquid water around biofilmsand planktonic bacteria, removing the need for brine veins to prevent bacterial freezing.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.