Cold environments, such as the Arctic, are often thought of as “extreme”. However, the ocean’s interior and much of the marine subsurface is constantly at temperatures close to 0 °C, meaning that much of Earth’s life thrives in the cold biosphere. Research in the Arctic probes how microbes live and metabolize in cold temperatures.
The permanently cold Arctic environments offer an attractive, accessible system in which to study cold adaptations of environmental microbes. Researchers at the Center for Geomicrobiology are involved in a long-term field research program in Svalbard in order to characterize microbial communities and biogeochemical processes in permanently cold Arctic fjord sediments and water column. In August 2010, Andrew Steen lead a group of researchers from five institutions in Denmark, Germany, Austria, and the United States to continue work in Svalbard. Arctic research at the Center for Geomicrobiology focuses on the following three themes: bacterial spores and microbial dispersal in the ocean; microbial metabolism in cold seawater; and characterization of organic matter in Arctic fjord sediments.
Certain microbes are capable of entering a highly robust, dormant life stage called a spore. Investigations of Svalbard fjord sediments have revealed a surprisingly high concentration of thermophilic spores – dormant microbes only capable of life at high temperatures (above 40-50 °C). What are these heat-loving microbes doing in permanently cold Arctic sediments? Researchers at Center for Geomicrobiology argue that these spores must be broadly distributed around the world. Thermophilic spores in the Arctic are a ‘dead-end’ – they will probably never germinate to become biologically active – but the fact that they can be found in such an environment indicates how microbes are distributed around the world, ‘waiting’ to land in an environment in which conditions are appropriate for growth.
Microbial activities (specifically sulfate reduction rates) vary widely among the Svalbard fjords. In one fjord, sulfate reduction rates have been observed comparable to those measured in temperate environments. How can microbial activity be so high at cold temperatures? We will characterize the molecular composition of Svalbard sediments and sediment porewater in order to analyze whether ‘freshness’ of organic matter alone can account for the differences in microbial activity.