Investigating the Microbial Ecology of Yellowstone Lake

Yellowstone National Park is well known for its geothermal features. Among microbiologists it is equally well known for its unique microbial ecology and extreme habitats associated with terrestrial hot springs, geysers, and fumaroles. Yellowstone Lake has also been shown to contain geothermal activity, and the presence of hydrothermal vents with water temperatures up to 120 ̊C have been reported. The vents emit a number of compounds which are important to microorganisms as nutrients for growth or substrates for energy. Thus, similar to the terrestrial habitats, Yellowstone Lake presents unique systems to assess microbial diversity and ecology. In order to examine the microbial ecology of the lake and its hydrothermal features, we have used both traditional culture and enrichment techniques to isolate bacteria, and modern molecular methods to assess the microbial diversity. For example, enrichment and cultural methods have yielded the characterization of a new genus and species of thermophilic sulfate-reducing bacteria, T h e r m o d e s u l f ovibrio yellowstonii, isolated from a hydrothermal vent in Sedge Bay. Introduction Microbial ecology is the study of microorganisms in relation to their biotic and abiotic environment. In practice, it has been described in a graduate student motto as “the study of physiology under the worst possible conditions” (Brock 1966). More recently, microbial ecology has also been indicated to be the link between all branches of microbiology (Zinder and Salyers 2001). In any case, similar to traditional ecology, microbial ecologists study individual organisms, populations (of individuals), communities (of populations), and ecosystems. This is done this with a variety of approaches and tools, including microscopy, culturing, molecular biology, and biochemistry. Much of what is studied by microbial ecologists revolves around three questions: (1) Who is out there? (2) How many are there? and (3) What are they doing? Yellowstone Lake has been considered to be oligotrophic (e.g., Remsen et al. 1990; Gresswell et al. 1994). In other words, it has a low amount of productivity and is nutrient-poor. However, recent reports have suggested that the levels of nutrients indicate it should be considered more mesotrophic, or have a higher level of productivity than previously believed (Kilham et al. 1996; Theriot et al. 1997). When applying the above questions to Yellowstone Lake, the task of answering them might appear to be somewhat daunting. The sheer size of the Investigating the Microbial Ecology of Yellowstone Lake