title: Bacterial lipoteichoic acid enhances cryosurvival.
abstract: 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, and with a few exceptions, antifreeze proteins are missing. We show that lipoteichoic acid (LTA), a biopolymer in the cell wall of Gram-positive bacteria, can be added to B. subtilis cultures and increase freeze tolerance. At 1 % w/v, LTA enables a 50 % survival rate, similar to the results obtained with 1 % w/v glycerol as measured with the resazurin cell viability assay. In the absence of added LTA or glycerol, a very small number of B. subtilis cells survive freezing. This suggests that an innate freeze tolerance mechanism exists. While cryoprotection can be provided by extracellular polymeric substances, our data demonstrate a role for LTA in cryoprotection. Currently, the exact mode of action for LTA cryoprotection is unknown. With a molecular weight of 3-5 kDa, it is unlikely to enter the cell cytoplasm. However, low temperature microscopy data show small ice crystals aligned along channels of liquid water. Our observations suggest that teichoic acids could protect liquid water within biofilms and planktonic bacteria, augmenting the role of brine while also raising the possibility for survival without brine present.
authors.affiliation: Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, 73019, USA, rice@ou.edu.
authors.forename: Charles V
authors.initials: CV
authors.lastname: Rice
authors.forename: Amy
authors.initials: A
authors.lastname: Middaugh
authors.forename: Jason R
authors.initials: JR
authors.lastname: Wickham
authors.forename: Anthony
authors.initials: A
authors.lastname: Friedline
authors.forename: Kieth J
authors.initials: KJ
authors.lastname: Thomas
authors.forename: Erin
authors.initials: E
authors.lastname: Scull
authors.forename: Karen
authors.initials: K
authors.lastname: Johnson
authors.forename: Malcolm
authors.initials: M
authors.lastname: Zachariah
authors.forename: Ravindranth
authors.initials: R
authors.lastname: Garimella
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects* / Q000502:physiology; D002473:Cell Wall / Q000187:drug effects; D003451:Cryoprotective Agents / Q000494:pharmacology*; D005615:Freezing; D008070:Lipopolysaccharides / Q000494:pharmacology*; D013682:Teichoic Acids / Q000494:pharmacology*
chemical_list: D003451:Cryoprotective Agents; D008070:Lipopolysaccharides; D013682:Teichoic Acids; C009900:lipoteichoic acid