Original Paper

Archives of Microbiology

, Volume 174, Issue 3, pp 152-161

Characterization of novel bacteriochlorophyll-a-containing red filaments from alkaline hot springs in Yellowstone National Park

  • Sarah M. BoomerAffiliated withWestern Oregon University, Department of Biology, 345 Monmouth Ave., Monmouth, OR 97361, USA
  • , Beverly K. PiersonAffiliated withDepartment of Biology, University of Puget Sound, 1500 N. Warner, Tacoma, WA 98416, USA
  • , Ruthann AustinhirstAffiliated withDepartment of Biology, University of Puget Sound, 1500 N. Warner, Tacoma, WA 98416, USA
  • , Richard W. CastenholzAffiliated withUniversity of Oregon, Department of Biology, Eugene, OR 97403, USA

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Novel red, filamentous, gliding bacteria formed deep red layers in several alkaline hot springs in Yellowstone National Park. Filaments contained densely layered intracellular membranes and bacteriochlorophyll a. The in vivo absorption spectrum of the red layer filaments was distinct from other phototrophs, with unusual bacteriochlorophyll a signature peaks in the near-infrared (IR) region (807 nm and 911 nm). These absorption peaks were similar to the wavelengths penetrating to the red layer of the mats as measured with in situ spectroradiometry. The filaments also demonstrated maximal photosynthetic uptake of radiolabeled carbon sources at these wavelengths. The red layer filaments displayed anoxygenic photoheterotrophy, as evidenced by the specific incorporation of acetate, not bicarbonate, and by the absence of oxygen production. Photoheterotrophy was unaffected by sulfide and oxygen, but was diminished by high-intensity visible light. Near-IR radiation supported photoheterotrophy. Morphologically and spectrally similar filaments were observed in several springs in Yellowstone National Park, including Octopus Spring. Taken together, these data suggest that the red layer filaments are most similar to the photoheterotroph, Heliothrix oregonensis. Notable differences include mat position and coloration, absorption spectra, and prominent intracellular membranes.

Photosynthetic bacteria Microbial mats Thermophiles Anoxygenic photosynthesis Gliding motility Bacteriochlorophyll Hot springs Green non-sulfur bacteria Photoheterotrophy Infrared radiation