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 (EPS), 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.

Viral challenges and adaptations between Central Arctic Ocean and atmosphere

“…Sixteen vOTUs carried the AMG glycerol-3-phosphate cytidylyltransferase or tagD [Enzyme Commission number, EC:2.7.7.39 ]. This gene encodes for an enzyme involved in the production of teichoic acids [88], which in turn benefit the freeze tolerance in bacteria [89, 90]. Three further AMGs were annotated as ice-binding-like [Pfam/InterPro database, PF11999.11], which as gene family includes ice-binding proteins (IBPs).…”

“…In addition to IBPs, we also found AMGs encoding for glycerol-3-phosphate cytidylyltransferase, which has a function in the biosynthesis of teichoic acid, a cell wall component of Gram-positive bacteria. Constituents of teichoic acids undergo chemical interactions that allow liquid water to be maintained within the cell wall and the immediate extracellular space [89, 90] thereby providing cryoprotection. Teichoic acids can be secreted into extracellular spaces, for instance within biofilms [103].…”

Deciphering the significant role of biological ice nucleators in precipitation at the organic molecular level

“…The presence of proteins, carbohydrates or lipid fractions with ice nucleation or antifreeze capabilities within the microorganism enable diverse biological entities to influence ice formation differently (Dreischmeier et al, 2017;O′Sullivan et al, 2015). Nonetheless, OM molecules were significantly smaller than intact cells (Govindarajan & Lindow, 1988;Pummer et al, 2012), and the possibility of organic compounds with varying ice nucleation abilities coexisting within the same microorganism cannot be discounted (Dreischmeier et al, 2017;Failor et al, 2017;Rice et al, 2015). Certain proteinaceous materials or carbohydrates possess both ice-binding and ice-nucleating abilities (Xu et al, 1998).…”

Extremophilic Exopolysaccharides: Biotechnologies and Wastewater Remediation

“…More recently, the aspects of commercial applications of extremophilic EPS in biotechnology have started to earn attention (Parwani et al, 2021). In the psychrophilic strains, EPS generates a thin sheet of water to thwart extracellular ice from destroying the cell surface and has been shown to act as a cryoprotectant against freezing (Krembs et al, 2002;Poli et al, 2010;Rice et al, 2015;López-Ortega et al, 2021). There is evidence that EPS in at least one of these strains can form a pseudohelicoidal structure that may prevent the formation of the local tetrahedral order of the water molecules in the first hydration shell and thwart extracellular ice from destroying the cell surface (Casillo et al, 2018).…”