Microbial Metabolism in Ice and Brine at −5°C

Summary Metabolic activity, but not growth, has been observed in ice at temperatures from −5°C to −32°C. To improve understanding of metabolism in ice, we simultaneously examined various aspects of metabolism ( 14 C‐acetate utilization, macromolecule syntheses and viability via reduction of CTC) of the glacial isolates Sporosarcina sp. B5 and Chryseobacterium sp. V3519‐10 during incubation in nutrient‐rich ice and brine at −5°C for 50 days. Measured rates of acetate utilization and macromolecule syntheses were high in the first 20 days suggesting adjustment to the lower temperatures and higher salt concentrations of both the liquid vein network in the ice and the brine. Following this adjustment, reproductive growth of both organisms was evident in brine, and suggested for Sporosarcina sp. B5 in ice by increases in cell numbers and biomass. Chryseobacterium sp. V3519‐10 cells incubated in ice remained active. These data indicate that neither low t