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Project Progress

In the main area of research, microbiology of hypersaline ecosystems, substantial progress was made. ~4000 new rRNA sequences were determined and thereby organisms were identified from hypersaline situations: microbial mat and crystallizing halite-gypsum (brine). Many new bacterial and archaeal clades were discovered, including ~15 new bacterial phylogenetic divisions (“kingdoms”). Surprisingly, cyanobacteria do not constitute the main biomass (rRNA gene content), rather, Green Nonsulfur Bacteria dominate numerically. This has implications for the interpretation of isotopic fractionation data. Numerous novel eucaryotes also were found. Most of the eucaryotic biomass resides with nematodes, abundant in this ecosystem. Several publications are being prepared based on findings.

In a second area of work, the biology of high-temperature ecosystems, we have completed analysis of Yellowstone systems >70°C. Notably, organisms identified molecularly as hydrogen-metabolizing constitute the most common life in those hot springs. We have now measured molecular hydrogen in a number of Yellowstone hot springs and find abundant hydrogen for metabolism (15-300 nM). Also in Yellowstone we have discovered and described a new form of endolithic community, in silica sinter perfused with volcanic gases inluding hydrogen sulfide, which results in low pore water pH (<1). The community is lichen-like, but the photobiont is the organism Cyanidium caldarium and a supporting filamentous comunity is comprised of unidentified mycobacteria, never previously seen in such conditions. The communities are rapidly encased in silica and thereby provide long-lived traces of past life that could be examples of important biosignatures on, e.g. Mars.