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

Geitlerinema terebriformis in contracted fascicles over Synechococcus topmat as a result of high, mid-day, summer light intensity. Temperature ~50 °C.
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life-05-00332-f006: Geitlerinema terebriformis in contracted fascicles over Synechococcus topmat as a result of high, mid-day, summer light intensity. Temperature ~50 °C.

Mentions: Although one the fastest growing isolates of Synechococcus (e.g., CCMEE strain No. 5241; OH 20) had its temperature for most rapid growth at about 45 °C [3,5], or strain 53 [3]. This temperature zone of the Synechococcus in the field did not reveal itself very often because of a dense cover of another cyanobacterium, Geitlerinema (Oscillatoria)cf.terebriformis (Figure 4). This motile oscillatorian formed a dark mat of intertwining filaments covering Synechococcus and all other phototrophs at 54–55 °C and below during most solar conditions (Figure 1 and Figure 5). This filamentous, motile cyanobacterium became the predominant phototroph up to about 54–55 °C (the highest limit and also nearly the maximum growth rate) [14]. This phenotype and 16S rDNA genotype is known from isolates from other hot springs in the eastern Oregon area, and even as distant as Saudi Arabia [4]. C-phycoerythrin is the primary light-harvesting pigment (545 nm maximum) giving the mat its dark color, although phycocyanin and allophycocyanin are present, as in almost all cyanobacteria. This cyanobacterial mat under low light was dense and continuous due to a mass of intertwining trichomes, and as a complete mat, and under low light (morning or afternoon in summer) absorbed up to 99% of visible radiation (Figure 5) and [15]. Normally, in response to high light intensity (e.g., after 9–10 am in summer and up to >1500 µE m−2 s−1 or 700 Wm−2) the motile trichomes of G. terebriformis responded in two ways. If the G. terebriformis mat rested on top of a rather hard “gelatinous” substrate, the main response was a mass clumping of trichomes into dense “balls” or “fascicles” (Figure 6). The rapidity of this response is temperature and light intensity dependent, e.g., [16,17,18]. Before 1967 the ecological advantage of this response was not obvious. It is now realized that the escape from high light inhibition occurs with this “clumping” phenomenon, since there is a continuous gliding motility of trichomes in contact with each other within the clump or fascicle so that no single one is exposed to high light for more that a few minutes or seconds. Since gliding motility requires a trichome rotation, the “tail-end” of a trichome is usually entangled with other trichomes, a compulsory contraction occurs. In culture, a dense, uniform suspension of trichomes in liquid medium spread in a 4.5 cm diameter glass petri plate contracts into a dense population of only 1 cm diameter in 130 s at 47 °C under ~40 Wm−2 irradiance, from coolwhite lamps, ~6% of highest outdoor intensity [16,17,18]. The rate of re-colonization of G. terebriformis on a denuded substrate in the field was ~1 cm hr−1 from the edge of an intact mat [16,17]. G. terebriformis trichomes can glide forward at ~0.5 mm−1 min under ideal temperature and light intensity [19].


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

Castenholz RW - Life (Basel) (2015)

Geitlerinema terebriformis in contracted fascicles over Synechococcus topmat as a result of high, mid-day, summer light intensity. Temperature ~50 °C.
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00332-f006: Geitlerinema terebriformis in contracted fascicles over Synechococcus topmat as a result of high, mid-day, summer light intensity. Temperature ~50 °C.
Mentions: Although one the fastest growing isolates of Synechococcus (e.g., CCMEE strain No. 5241; OH 20) had its temperature for most rapid growth at about 45 °C [3,5], or strain 53 [3]. This temperature zone of the Synechococcus in the field did not reveal itself very often because of a dense cover of another cyanobacterium, Geitlerinema (Oscillatoria)cf.terebriformis (Figure 4). This motile oscillatorian formed a dark mat of intertwining filaments covering Synechococcus and all other phototrophs at 54–55 °C and below during most solar conditions (Figure 1 and Figure 5). This filamentous, motile cyanobacterium became the predominant phototroph up to about 54–55 °C (the highest limit and also nearly the maximum growth rate) [14]. This phenotype and 16S rDNA genotype is known from isolates from other hot springs in the eastern Oregon area, and even as distant as Saudi Arabia [4]. C-phycoerythrin is the primary light-harvesting pigment (545 nm maximum) giving the mat its dark color, although phycocyanin and allophycocyanin are present, as in almost all cyanobacteria. This cyanobacterial mat under low light was dense and continuous due to a mass of intertwining trichomes, and as a complete mat, and under low light (morning or afternoon in summer) absorbed up to 99% of visible radiation (Figure 5) and [15]. Normally, in response to high light intensity (e.g., after 9–10 am in summer and up to >1500 µE m−2 s−1 or 700 Wm−2) the motile trichomes of G. terebriformis responded in two ways. If the G. terebriformis mat rested on top of a rather hard “gelatinous” substrate, the main response was a mass clumping of trichomes into dense “balls” or “fascicles” (Figure 6). The rapidity of this response is temperature and light intensity dependent, e.g., [16,17,18]. Before 1967 the ecological advantage of this response was not obvious. It is now realized that the escape from high light inhibition occurs with this “clumping” phenomenon, since there is a continuous gliding motility of trichomes in contact with each other within the clump or fascicle so that no single one is exposed to high light for more that a few minutes or seconds. Since gliding motility requires a trichome rotation, the “tail-end” of a trichome is usually entangled with other trichomes, a compulsory contraction occurs. In culture, a dense, uniform suspension of trichomes in liquid medium spread in a 4.5 cm diameter glass petri plate contracts into a dense population of only 1 cm diameter in 130 s at 47 °C under ~40 Wm−2 irradiance, from coolwhite lamps, ~6% of highest outdoor intensity [16,17,18]. The rate of re-colonization of G. terebriformis on a denuded substrate in the field was ~1 cm hr−1 from the edge of an intact mat [16,17]. G. terebriformis trichomes can glide forward at ~0.5 mm−1 min under ideal temperature and light intensity [19].

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