Algal Species and Light Microenvironment in a Low-pH, Geothermal Microbial Mat Community

Abstract

Unicellular algae are the predominant microbial mat-forming phototrophs in the extreme environments of acidic geothermal springs. The ecology of these algae is not well known because concepts of species composition are inferred from cultivated isolates and microscopic observations, methods known to provide incomplete and inaccurate assessments of species in situ. We used sequence analysis of 18S rRNA genes PCR amplified from mat samples from different seasons and different temperatures along a thermal gradient to identify algae in an often-studied acidic (pH 2.7) geothermal creek in Yellowstone National Park. Fiber-optic microprobes were used to show that light for algal photosynthesis is attenuated to <1% over the 1-mm surface interval of the mat. Three algal sequences were detected, and each was present year-round. A Cyanidioschyzon merolae sequence was predominant at temperatures of >49°C. A Chlorella protothecoides var. acidicola sequence and a Paradoxia multisita-like sequence were predominant at temperatures of <39°C.

Biogeographic and Phylogenetic Diversity of Thermoacidophilic Cyanidiales in Yellowstone National Park, Japan, and New Zealand

“…3, compare panels A and B). The isolation of this type of organism in the current study serves to verify the previous reports of similar identity uncertainty by Ferris et al (10) and Lehr et al (17). More importantly, the extensive …”

“…or C. merolae in this one endolithic sample. In contrast, we did not detect any C. caldarium phylotypes through extensive culturing attempts from collections in YNP, Japan, and New Zealand, nor has C. caldarium been detected in 18S rDNA molecular surveys of Dragon Spring in Norris Geyser Basin (17) or in Nymph Creek (10), both in YNP. The paper by Walker et al (36) claims to have identified a cyanidial sequence closest to C. caldarium from an endolithic sample in the Norris Geyser Basin, but we believe this claim is in error (unpublished data).…”

Burning coal spoil heaps as a new habitat for the extremophilic red alga Galdieria sulphuraria

“…For example, it is well known from Italy (Gross et al 1998;CiNiglia et al 2004;YooN et al 2006;PiNto et al 2007), Yellowstone National Park, USA (Ferris et al 2005;Skorupa et al 2013), New Zealand (TopliN et al 2008 and Iceland (CiNiglia et al 2014). Rocks and sediments surrounding hot sulphur springs, steaming fumaroles or boiling mud pools are typical habitats for this extremophile (Gross et al 1998;CiNiglia et al 2004CiNiglia et al , 2014Ferris et al 2005;YooN et al 2006;PiNto et al 2007;TopliN et al 2008;Skorupa et al 2013;Hsieh et al 2015). Although Galdieria is found all over the world, its distibution is discontinuous due to special growth and habitat requirements.…”

Conserved structure of Snu13 from the highly reduced spliceosome of Cyanidioschyzon merolae

“…1 Cyanidioschyzon merolae is a unicellular red alga that lives in geothermal springs at temperatures of 42-568C and pH of 1.5-3. 2 The genome contains only 27 introns; in contrast, the Saccharomyces cerevisiae (yeast) genome, of similar size, has more than 250. 3,4 We recently reported a computational and biochemical assessment of the C. merolae splicing factor complement that revealed a substantial reduction in core splicing proteins to only 40.…”