The role of microbial extracellular polymeric substances in psychrotolerance and geochemistry of subglacial environments

Extracellular polymeric substances (EPS) were investigated to determine their potential role in microbial cryotolerance in the subglacial environment. The cell surface chemistry of Hymenobacter aerophilus cells, with and without EPS, was determined using potentiometric titrations and cadmium adsorption assays. The presence of EPS was associated with an increase in both variety and quantity of surface ligands available for environmental interactions and resulted in an increase in adsorbed cadmium. Survival of a freeze-thaw cycle with and without EPS was tested with Flavobacterium A97, a subglacial isolate, in the presence and absence of a variety of particulate substrata. Most probable number (MPN) and plate count data were unable to provide sufficient resolution to test the hypothesis that EPS production and the presence of a substratum would be associated with increased survival of a freeze-thaw cycle.