Physiology, Metabolism, and Fossilization of Hot-Spring Filamentous Microbial Mats

Abstract

The evolutionarily ancient Aquificales bacterium Sulfurihydrogenibium spp. dominates filamentous microbial mat communities in shallow, fast-flowing, and dysoxic hot-spring drainage systems around the world. In the present study, field observations of these fettuccini-like microbial mats at Mammoth Hot Springs in Yellowstone National Park are integrated with geology, geochemistry, hydrology, microscopy, and multi-omic molecular biology analyses. Strategic sampling of living filamentous mats along with the hot-spring CaCO3 (travertine) in which they are actively being entombed and fossilized has permitted the first direct linkage of Sulfurihydrogenibium spp. physiology and metabolism with the formation of distinct travertine streamer microbial biomarkers. Results indicate that, during chemoautotrophy and CO2 carbon fixation, the 87–98% Sulfurihydrogenibium-dominated mats utilize chaperons to facilitate enzyme stability and function. High-abundance transcripts and proteins for type IV pili and extracellular polymeric substances (EPSs) are consistent with their strong mucus-rich filaments tens of centimeters long that withstand hydrodynamic shear as they become encrusted by more than 5 mm of travertine per day. Their primary energy source is the oxidation of reduced sulfur (e.g., sulfide, sulfur, or thiosulfate) and the simultaneous uptake of extremely low concentrations of dissolved O2 facilitated by bd-type cytochromes. The formation of elevated travertine ridges permits the Sulfurihydrogenibium-dominated mats to create a shallow platform from which to access low levels of dissolved oxygen at the virtual exclusion of other microorganisms. These ridged travertine streamer microbial biomarkers are well preserved and create a robust fossil record of microbial physiological and metabolic activities in modern and ancient hot-spring ecosystems.

Volcanic controls on the microbial habitability of Mars‐analogue hydrothermal environments

“…Sulfurihydrogenibium dominates at KR‐Bio and likely performs dark oxidation of sulphur compounds and molecular hydrogen (Figure 10). It also has been identified in other Icelandic hydrothermal locations (Flores et al., 2008) and at Mammoth Hot Spring, Yellowstone National Park, USA (Dong et al., 2019). Sulfurihydrogenibium is an evolutionarily primitive taxon often found dominating filamentous microbial mat communities in shallow fast flowing aqueous systems globally (Dong et al., 2019).…”

Spatial Metagenomics of Three Geothermal Sites in Pisciarelli Hot Spring Focusing on the Biochemical Resources of the Microbial Consortia

“…Living at such selective pressure might foster the development and retention of a suite of metabolic and physiological adaptations, which could play a key role in ensuring the presence and persistence of life in extreme environments [ 51 ].…”

In Vivo Entombment of Bacteria and Fungi during Calcium Oxalate, Brushite, and Struvite Urolithiasis

“…Each of these biomineralization steps is promoted and/or inhibited by a variety of physical, chemical and biological processes and mechanisms (4). Importantly, the deposition of minerals that form human kidney stones (5) is directly comparable to biomineralization processes in other natural and man-made environments (6), all of which are strongly influenced by microorganisms (collectively called the microbiome) (7). For example, in hot-spring calcium carbonate (CaCO 3 ) travertine deposits, bacteria control mineral growth rate, mineralogy, and crystalline structure (6).…”