Limits...
Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

Castenholz RW - Life (Basel) (2015)

Bottom Line: All of these demarcations are easily visible in the field.In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology.Most of the temperature and chemical limits have been explained by field and laboratory experiments.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA. rcasten@uoregon.edu.

ABSTRACT
Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments.

No MeSH data available.


Related in: MedlinePlus

Swarm of swimming, ascending Thermochromatium tepidum (pink cloud at right) that had been covered by an opaque can for 2 h during 10 am on a cloudy day. In uncovered area, daytime cover of Geitlerinema terebriformis remained.
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life-05-00332-f016: Swarm of swimming, ascending Thermochromatium tepidum (pink cloud at right) that had been covered by an opaque can for 2 h during 10 am on a cloudy day. In uncovered area, daytime cover of Geitlerinema terebriformis remained.

Mentions: In some slow-flowing streams and warm pools (35–40 °C) in the southern part of the Hunter’s cluster of springs, sulfide concentrations (mainly HS− at pH ~8.0–8.2) have been measured at 0.5 mM at the mat surface at night and up to 0.8 mM at 2–3 mm depth even in the daylight [18]. It was obvious that the high sulfide was a result of biogenic sulfate reduction, since soluble sulfide was absent in the inorganic source waters, and H2S arose from the mat at night with a strong odor [18]. In these pools and slow streams, at temperatures of ~50 °C and lower, a conspicuous under layer of purple sulfur bacteria (i.e., Thermochomatiumcf.tepidum) appeared at the top of the mat in darkness (Figure 15). Often, these flagellated cells swarmed at night (en masse) into the somewhat toxic water above, as pink clouds with cells containing “endocellular” grains of elemental sulfur (Figure 16). Although anoxygenic photosynthesis of the purple sulfur bacteria uses soluble sulfide as photo-reductant during daytime, at night the internal elemental sulfur of the cells gradually disappeared as the cells may have continued to grow, presumably using the internal S0 and O2 for aerobic chemo-litho-trophy [28].


Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

Castenholz RW - Life (Basel) (2015)

Swarm of swimming, ascending Thermochromatium tepidum (pink cloud at right) that had been covered by an opaque can for 2 h during 10 am on a cloudy day. In uncovered area, daytime cover of Geitlerinema terebriformis remained.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390855&req=5

life-05-00332-f016: Swarm of swimming, ascending Thermochromatium tepidum (pink cloud at right) that had been covered by an opaque can for 2 h during 10 am on a cloudy day. In uncovered area, daytime cover of Geitlerinema terebriformis remained.
Mentions: In some slow-flowing streams and warm pools (35–40 °C) in the southern part of the Hunter’s cluster of springs, sulfide concentrations (mainly HS− at pH ~8.0–8.2) have been measured at 0.5 mM at the mat surface at night and up to 0.8 mM at 2–3 mm depth even in the daylight [18]. It was obvious that the high sulfide was a result of biogenic sulfate reduction, since soluble sulfide was absent in the inorganic source waters, and H2S arose from the mat at night with a strong odor [18]. In these pools and slow streams, at temperatures of ~50 °C and lower, a conspicuous under layer of purple sulfur bacteria (i.e., Thermochomatiumcf.tepidum) appeared at the top of the mat in darkness (Figure 15). Often, these flagellated cells swarmed at night (en masse) into the somewhat toxic water above, as pink clouds with cells containing “endocellular” grains of elemental sulfur (Figure 16). Although anoxygenic photosynthesis of the purple sulfur bacteria uses soluble sulfide as photo-reductant during daytime, at night the internal elemental sulfur of the cells gradually disappeared as the cells may have continued to grow, presumably using the internal S0 and O2 for aerobic chemo-litho-trophy [28].

Bottom Line: All of these demarcations are easily visible in the field.In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology.Most of the temperature and chemical limits have been explained by field and laboratory experiments.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA. rcasten@uoregon.edu.

ABSTRACT
Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments.

No MeSH data available.


Related in: MedlinePlus