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

Hunter’s Springs from over ~93 °C at source (gray) to the green biofilm of Synechococcus (73–74 °C) that ends at 54–55 °C with the dark brown cover of Geitlerinema (Oscillatoria) cf. terebriformis, some of which has contracted to expose a salmon-colored undermat of Chloroflexus that had been hidden by the top-mat of the cyanobacterium, G. terebriformis.
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life-05-00332-f001: Hunter’s Springs from over ~93 °C at source (gray) to the green biofilm of Synechococcus (73–74 °C) that ends at 54–55 °C with the dark brown cover of Geitlerinema (Oscillatoria) cf. terebriformis, some of which has contracted to expose a salmon-colored undermat of Chloroflexus that had been hidden by the top-mat of the cyanobacterium, G. terebriformis.

Mentions: The 93 °C water of some sources and water flowing downstream above 74 °C at Hunter’s presumably harbored non-photosynthetic Bacteria and Archaea, but these have not been identified. These clear water stream outpourings were generally not more than 1–3 cm in depth, although thermal pools were sometimes over a meter deep at the central source. At a mean temperature of 73–74 °C, a green edge of a biofilm or cover of Synechococcus sp. appeared and continued to about 55 °C, although below about 68–70 °C, a somewhat thicker mat with members of the Chloroflexi (e.g., Chloroflexus sp.) developed below, with the Synechococcus biofilm on top (Figure 1 and Figure 2). The green cover consisted of one or more species or strains of unicellular, rod-shaped, photoautotrophic Synechococcus to 55 °C (Figure 3). With decreases in the temperature gradient at least four thermotypes with identical morphology occurred [3,4]. This was confirmed by a later study that again recognized four or more thermotypes, each isolate with a distinctive growth rate measured over its complete temperature range [4,5]. These results, placed in phylogenetic context indicated that the highest temperature strain (University of Oregon, Culture Collection of Microorganisms from Extreme Environments strain No. 5245; OH 28) capable of growth to >70 °C, was ancestrally derived from lower temperature strains [5]. Additional information on the evolution of thermal stable Ribulose Bisphosphate Carboxylase/Oxygenase of the highest temperature and lower temperature strains has been provided [6,7]. Lower temperature strains grew with higher maximum growth rates than the high temperature type. In short, the highest temperature strain traded off a lower growth rate maximum and inability to grow at lower temperatures (<55 °C) with a higher temperature range. A similar and probably identical high temperature strain isolated from Hunter’s was characterized earlier by Meeks and Castenholz [8,9,10], who showed that this strain was an obligate thermophile with no net growth below about 55 °C. All of the Synechococcus strains, in field or culture, contain c-phycocyanin, allophycocyanin and chlorophyll a as the light-harvesting pigments.


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

Castenholz RW - Life (Basel) (2015)

Hunter’s Springs from over ~93 °C at source (gray) to the green biofilm of Synechococcus (73–74 °C) that ends at 54–55 °C with the dark brown cover of Geitlerinema (Oscillatoria) cf. terebriformis, some of which has contracted to expose a salmon-colored undermat of Chloroflexus that had been hidden by the top-mat of the cyanobacterium, G. terebriformis.
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00332-f001: Hunter’s Springs from over ~93 °C at source (gray) to the green biofilm of Synechococcus (73–74 °C) that ends at 54–55 °C with the dark brown cover of Geitlerinema (Oscillatoria) cf. terebriformis, some of which has contracted to expose a salmon-colored undermat of Chloroflexus that had been hidden by the top-mat of the cyanobacterium, G. terebriformis.
Mentions: The 93 °C water of some sources and water flowing downstream above 74 °C at Hunter’s presumably harbored non-photosynthetic Bacteria and Archaea, but these have not been identified. These clear water stream outpourings were generally not more than 1–3 cm in depth, although thermal pools were sometimes over a meter deep at the central source. At a mean temperature of 73–74 °C, a green edge of a biofilm or cover of Synechococcus sp. appeared and continued to about 55 °C, although below about 68–70 °C, a somewhat thicker mat with members of the Chloroflexi (e.g., Chloroflexus sp.) developed below, with the Synechococcus biofilm on top (Figure 1 and Figure 2). The green cover consisted of one or more species or strains of unicellular, rod-shaped, photoautotrophic Synechococcus to 55 °C (Figure 3). With decreases in the temperature gradient at least four thermotypes with identical morphology occurred [3,4]. This was confirmed by a later study that again recognized four or more thermotypes, each isolate with a distinctive growth rate measured over its complete temperature range [4,5]. These results, placed in phylogenetic context indicated that the highest temperature strain (University of Oregon, Culture Collection of Microorganisms from Extreme Environments strain No. 5245; OH 28) capable of growth to >70 °C, was ancestrally derived from lower temperature strains [5]. Additional information on the evolution of thermal stable Ribulose Bisphosphate Carboxylase/Oxygenase of the highest temperature and lower temperature strains has been provided [6,7]. Lower temperature strains grew with higher maximum growth rates than the high temperature type. In short, the highest temperature strain traded off a lower growth rate maximum and inability to grow at lower temperatures (<55 °C) with a higher temperature range. A similar and probably identical high temperature strain isolated from Hunter’s was characterized earlier by Meeks and Castenholz [8,9,10], who showed that this strain was an obligate thermophile with no net growth below about 55 °C. All of the Synechococcus strains, in field or culture, contain c-phycocyanin, allophycocyanin and chlorophyll a as the light-harvesting pigments.

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