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Nostoc pruniforme. Photosynthesis of N. pruniforme versus availability of free CO 2 changed by manipulating pH in water with constant dissolved inorganic carbon (0.883 mmol l-1 ). When fitted to a modified Michaelis-Menten equation, the photosynthetic rate at 'zero' free CO 2 was 56% of V max , and the estimated K m was 0.12 mmol CO 2 l-1
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Nostoc pruniforme is a freshwater cyanobacterium forming large spherical colonies of up to several centimeters in diameter. The size and shape result in low surface area to volume (SA/V) ratios that potentially put severe constraints on resource acquisition. In the present study we have specifically examined how N. pruniforme copes with the acquisi...
Citations
... Nostoc pruniforme forms a beautiful, dark green, spherical colony with a smooth surface like a plume. It is more common and widely distributed both geographically and ecologically in oligo-and mesotrophic freshwaters in temperate and sub-Arctic regions than its rare freshwater cousin, N. zetterstedtii (Dodds et al., 1995;Raun et al., 2009). Danish alkaline lakes housing N. pruniforme contain .0 . ...
... 01 g FM cm -3 while colonies of N. zetterstedtii from oligotrophic Lake Värsjö have a specific density of 1 . 13 g FM cm -3 (Raun et al., 2009;Sand-Jensen et al., 2009b). Both species have gradually decreasing mass specific density for larger colonies, which tend to be hollow and water-filled in the centre of N. pruniforme and possess a massive, though less dense, structure without trichomes in N. zetterstedtii ( Table 2). ...
... Because resource uptake in phototrophic organisms scales to surface area while resource demand scales to volume and mass, a first principle dictates that relative growth rate scales to SA:V and CMA (Nielsen and Sand-Jensen, 1990;Poorter, 1992, 2004). Studies on N. pruniforme and N. zetterstedtii show that chlorophyll content and photosynthetic capacity relative to surface area are approximately independent of colony size because the Nostoc trichomes are mainly confined to the 1 -2 mm-thick outer periphery of the spherical colony, while its dark central part is mostly devoid of trichomes and photosynthetic activity (Raun et al., 2009;Sand-Jensen et al., 2009b). If Nostoc colonies produce hollow spheres with an outer shell of uniform thickness and a water-filled central cavity, CMA would be independent of colony size, just as in the uniformly thick thalli of many macroalgae, plant leaves and the sheet-like structure of N. commune. ...
Background The cyanobacterial genus Nostoc includes several species forming centimetre-large gelatinous colonies in nutrient-poor freshwaters and harsh semi-terrestrial
environments with extended drought or freezing. These Nostoc species have filaments with normal photosynthetic cells and N2-fixing heterocysts embedded in an extensive gelatinous matrix of polysaccharides and many other organic substances providing
biological and environmental protection. Large colony size imposes constraints on the use of external resources and the gelatinous
matrix represents extra costs and reduced growth rates.
In the emerging field of algal biotechnology, optimization of algal production, engineering challenges, and scale-up of photobioreactors are urgent demands. Emphasis is placed on reducing cultivation limitations regarding, e.g., mass transfer, thermostability, photoinhibition, as well as expenses for energy and resource investments. Until now, almost all cultivation techniques are processed under submerged conditions with aquatic microalgae. The biotechnological implementation of terrestrial microalgae, however, exhibits several physiological and technological advantages for an efficient production in biofilm photobioreactors. Their outstanding performance and considerable advantages for biotechnology may reduce several of the current limitations and provide new principles in bioengineering. Can they outcompete the capacity of commercial algal strain due to their thermostability, light utilization, or desiccation tolerance? How terrestrial microalgae could highly contribute to technological and economic improvement of microalgal biotechnology is discussed reviewing their species diversity, physiology, valuable products, bioengineering processes, biofilm photobioreactors, and some visions of potential developments. Moreover, the overview may allow choosing interesting organisms for further studies.
This article is the first comprehensive account about the occurrence of the cyanobacterium Nostoc pmniforme in Norway. The investigation was carried out in a rocky pool inhabited by the species. The locality is situated at the GPS-position: N.Lat. 71° 04′ 657″, E. Long. 028° 14′ 754″, in Slettnes nature reserve, Finnmark. The objectives of this study were to explore the organism in its limnological setting, and to throw light on autecological and synecological features together with the prevailing environmental conditions. The research work included studies both in the field and tha laboratory. For identification purposes isolation and purification of cyanobacteria were performed using culture techniques. The relevant strain of Nostoc pruniforme NIVA-CYA 648 is kept in the NIVA Culture Collection. This organism is available to members of the scientific community for non commercial purposes.
All cyanobacteria are actually or potentially photolithotrophic, with the exception of a recently discovered non-auotrophic free-living diazotroph which is presumably a (photo-)organotroph. Photolithotrophy involves CO2 assimilation by Form 1A or Form 1B Rubiscos with low affinity for CO2 and a small discrimination between CO2 and O2 and, at present CO2 levels, invariably involves an inorganic carbon concentrating mechanism (CCM). About half of the cyanobacterial strains tested are facultatively photo-organotrophic, a few of which are also facultative chemo-organotrophs; the rest are obligate photolithotrophs. In the natural environment the best-established cases of photo- or chemo-organotrophy are in symbioses of diazotrophic cyanobacteria with organisms that are already photosynthetic. The quantitative contribution of dissolved organic matter to otherwise photolithotrophically growing cyanobacteria is unclear. Extent cyanobacteria are involved in both biologically mediated calcification (direct role of the organism) and biologically related calcification (indirect role of the organism). The timing of the evolution of cyanobacterial CCM is unclear: the CCM probably evolved in low-CO2 episodes in the late Neoproterozoic or the Carboniferous, with spread to all cyanobacteria in the already established major clades by horizontal gene transfer. Cyanobacteria may be the last surviving photolithotrophs as the sun emits more energy and (by whatever mechanism) there is a decreased greenhouse gas, including CO2, content, of the atmosphere. © 2012 Springer Science+Business Media B.V. All rights reserved.
The cyanobacterial genus Nostoc includes several species forming large spherical or sheet‐like gelatinous colonies of ecological importance in freshwater and semi‐terrestrial habitats. We tested differences in morphology, growth and metabolism across a range of temperatures (6–43 °C) of three colonial species of Nostoc collected and grown in ambient water from typical localities from Denmark and Sweden: the plume‐shaped Nostoc pruniforme , the rare blackberry‐shaped Nostoc zetterstedtii and the semi‐terrestrial, sheet‐like Nostoc commune .
All three species grew and photosynthesised in water between 6 and 33 °C in our experiments but died at 43 °C. The optimum temperature of around 25 °C and the critical temperature of around 33 °C are markedly higher than mean and maximum temperatures in the majority of habitats of N. pruniforme and N. zetterstedtii, suggesting that their distribution does not reflect temperature preference directly. Although N. commune survives deep‐freezing and heating to 70 °C, sustained growth was restricted to 0–33 °C.
Maximum growth rates were relatively high for N. pruniforme and N. commune (doubling time of 13–15 days) and extremely low for N. zetterstedtii (doubling time of 2.4 years). Rates of photosynthesis, respiration and growth were markedly higher in alkaline water than in softwater, but N. pruniforme still grew much faster than N. zetterstedtii in the same water. Declines of growth and photosynthetic rates with increasing ratio of dry weight to surface area between the species and with increasing colony size reflect higher respiratory costs relative to resource uptake.
We conclude that the three Nostoc species have similar temperature tolerance from 6 to 43 °C, despite large interspecific differences in rates of growth and photosynthesis, colony persistence and distribution.
Aufbau und ihren Spezi-fikationen. Allen Reaktoren gemein ist dabei, dass sie ausschließlich für submerse Fermentationen geeignet sind. Im Rahmen eines DFG-Projektes (UL 170/7-1 und LA 1426/9-1) wird derzeit ein Photobioreaktor entwickelt, mit dem es möglich ist, phototrophe, aerophile Organismen auch emers (luftexponiert) zu kultivieren. Untersucht werden ter-restrische Cyanobakterien, da diese auf-grund ihres Sekundärmetabolit-Spek-trums ein großes biotechnologisches Potenzial besitzen. Darüber hinaus zeich-nen sich diese Organismen durch eine relativ gute physiologische Plastizität ge-genüber verschiedenen Kultivierungsbe-dingungen wie Licht, Temperatur und Wasserverfügbarkeit aus. Der neue Pho-tobioreaktor ist so konzipiert, dass er diese Eigenschaften der Organismen optimal ausnutzt. Der Reaktor wird über in den Reaktor reichende Lichtwellenleiter, die gleichzeitig als Anheftungsfläche für die Cyanobakterien dienen, beleuchtet. Zusätzlich wurden die Oberflächen hin-sichtlich Lichtverteilung und Adhäsion der Cyanobakterien optimiert. Die Nähr-stoffversorgung wird über die Zugabe eines Aerosols realisiert. Spezielle Stoff-wechselvorgänge, z. B. durch Austrock-nung oder Hitze induziert, können so ge-zielt gesteuert werden.
Nostoc commune is a widespread colonial cyanobacterium living on bare soils that alternate between frost and thaw, drought and inundation and very low and high temperatures. We collected N. commune from alternating wet and dry limestone pavements in Sweden and tested its photosynthesis and respiration at 20°C after exposure to variations in temperature (-269 to 105°C), pH (2-10) and NaCl (0.02-50 g NaCl kg(-1)). We found that dry field samples and rewetted specimens tolerated exposure beyond that experienced in natural environmental conditions: -269 to 70°C, pH 3-10 and 0-20 g NaCl kg(-1), with only a modest reduction of respiration, photosynthesis and active carbon uptake at 20°C. (14)CO(2) uptake from air declined markedly below zero and above 55°C, but remained positive. Specimens maintained a high metabolism with daily exposure to 6 h of rehydration and 18 h of desiccation at -18 and 20°C, but died at 40°C. The field temperature never exceeded the critical 40°C threshold during the wet periods, but it frequently exceeded this temperature during dry periods when N. commune is already dry and unaffected. We conclude that N. commune has an excellent tolerance to low temperatures, long-term desiccation and recurring cycles of desiccation and rewetting. These traits explain why it is the pioneer species in extremely harsh, nutrient-poor and alternating wet and dry environments.
