Anoxygenic Phototrophs Span Geochemical Gradients and Diverse Morphologies in Terrestrial Geothermal Springs

Abstract

There is a long and rich history of literature on phototrophs in terrestrial geothermal springs. These studies have revealed sulfide, pH, and temperature are the main constraints on phototrophy. However, the taxonomic and physiological diversity of anoxygenic phototrophs suggests that, within these constraints, specific geochemical parameters determine the distribution and activity of individual anoxygenic phototrophic taxa. Here, we report the recovery of sequences affiliated with characterized anoxygenic phototrophs in sites that range in pH from 2 to 9 and in temperature from 31°C to 71°C. Transcript abundance indicates anoxygenic phototrophs are active across this temperature and pH range. Our data suggest sulfide is not a key determinant of anoxygenic phototrophic taxa and underscore a role for photoheterotrophy in terrestrial geothermal ecosystems. These data provide the framework for high-resolution sequencing and in situ activity approaches to characterize the physiology of specific anoxygenic phototrophic taxa across a broad range of temperatures and pH.

Temperature impacts community structure and function of phototrophic Chloroflexi and Cyanobacteria in two alkaline hot springs in Yellowstone National Park

“…As expected based on previous studies of alkaline hot springs, more than 50% of the OTUs were classified as either Chloroflexi or Cyanobacteria (Fig. 1) (Brock, 1978;Bateson and Ward, 1988;Nübel et al, 2002;Bhaya et al, 2007;Miller et al, 2009;Rozanov et al, 2017;Alcamán-Arias et al, 2018, reviewed in Thiel et al, 2018Hamilton et al, 2019). Chloroflexi richness (OTUs per sample) did not show a linear trend with temperature ( Fig.…”

“…Photosynthetic bacteria are key primary producers in alkaline, terrestrial hot springs and a rich history of research has focused on phototrophs in Yellowstone National Park (YNP) (Pierson and Castenholz, 1974;Madigan and Brock, 1977; reviewed in the study by Tank et al, 2017;Hamilton et al, 2019). Hot springs provide a framework to test the ecophysiology of phototrophs in situ because they are dynamic and complex environments with natural gradients of temperature, sulfide and pH that harbour highly adapted microbial communities.…”

“…Hot springs provide a framework to test the ecophysiology of phototrophs in situ because they are dynamic and complex environments with natural gradients of temperature, sulfide and pH that harbour highly adapted microbial communities. Cyanobacteria and Chloroflexi are two phyla that contain putative phototrophs commonly observed in alkaline hot springs (Miller et al, 2009; reviewed in the study by Tank et al, 2017, Hamilton et al, 2019. While decades of work in several Yellowstone Hot Springs have shown that Cyanobacteria are constrained by temperature (Ward et al 1998;Becraft et al, 2011Becraft et al, , 2015, reviewed in the study by Ward et al, 2012), even at the ecotype level (Ward et al, 2006), the effect of temperature on the distribution of Chloroflexi in hot springs remains unresolved.…”

Metabolic diversity and co-occurrence of multiple Ferrovum species at an acid mine drainage site

“…To examine water geochemistry including major ions, major cations, trace elements, and carbon concentration and isotopes, samples were collected and stored following previously described methods [39][40][41]. In brief, samples were collected in a 140-mL syringe, filtered through 0.8/0.2 μm polyethersulfone syringe filters, and dispensed into 15-mL polypropylene centrifuge tubes (for major anions), acid-washed 15-mL polypropylene centrifuge tubes (for major cations and trace elements), Labco Exetainers® (Labco Limited, Lampeter, UK) preflushed with He (for dissolved inorganic carbon (DIC)), and sterile 50-mL centrifuge tubes (for dissolved organic carbon (DOC)).…”

“…In situ microcosms were performed to assess the potential for inorganic carbon uptake through the addition of NaH 13 CO 3 . Sample collection and the microcosm set-up followed previously described methods [39][40][41]. In summary, samples (biofilms, filaments, etc.)…”