To Live in a World of Metals: Robust Microbial Communities of the Great Salt Lake

The Great Salt Lake, particularly the north arm, lives up to its name with extremely high concentrations of group 1 and 2 elements, particularly sodium, magnesium, lithium, and potassium. A variety of other metals can also be found in the north arm, many of which would be toxic to most life given the high concentrations found in the lake. Despite this caveat, many organisms find ways to survive and even rely on these extreme conditions, especially halophilic microorganisms. There are a variety of mechanisms in which these microorganisms have adapted to their environment, but beyond basic survival, halophiles can also utilize some of the metals around them and may even accumulate and sequester them. To get a better idea about the microbial population of the Great Salt Lake and the challenges microbes face, we undertook a comprehensive analysis of the metal and microbe content, using ICP-MS and metagenomic analysis. To determine the extent to which halophiles sequester metal, environmental water samples with and without microbes present were analyzed—samples containing microbes were taken before filtration. The water analysis confirmed the extreme salt content of the lake, with large concentrations of group 1 and 2 elements predominating in the analysis. Despite their already high concentration, the water analysis suggests that microbes may be retaining a significant amount of group 1 and 2 elements, more so than other elements. Our metagenomic analyses uncovered a very large population of extreme archaeal and bacterial halophiles, which might be playing a role in metal sequestration. As proof of concept that metals could be sequestered by halophiles, the lab strain, Halobacterium salinarum sp. NRC-1, will be grown in the presence of different metals; the concentrations of the metals will be determined before and after growth to see if they are taken up by, used, and/or sequestered by the halobacteria. Understanding extremely metal-rich environments and how microbes live in them will lead to a better understanding of why and how metals are utilized by microbes. This may, in turn, lead us to a better understanding of the limits of life