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1.
Adaptation and Acclimation of Photosynthetic Microorganisms to Permanently Cold Environments 总被引:5,自引:0,他引:5
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Rachael M. Morgan-Kiss John C. Priscu Tessa Pocock Loreta Gudynaite-Savitch Norman P. A. Huner 《Microbiological reviews》2006,70(1):222-252
Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages. 相似文献
2.
Morgan-Kiss RM Ivanov AG Modla S Czymmek K Hüner NP Priscu JC Lisle JT Hanson TE 《Extremophiles : life under extreme conditions》2008,12(5):701-711
Permanently low temperature environments are one of the most abundant microbial habitats on earth. As in most ecosystems, photosynthetic organisms drive primary production in low temperature food webs. Many of these phototrophic microorganisms are psychrophilic; however, functioning of the photosynthetic processes of these enigmatic psychrophiles (the "photopsychrophiles") in cold environments is not well understood. Here we describe a new chlorophyte isolated from a low temperature pond, on the Ross Ice Shelf near Bratina Island, Antarctica. Phylogenetic and morphological analyses place this strain in the Chlorella clade, and we have named this new chlorophyte Chlorella BI. Chlorella BI is a psychrophilic species, exhibiting optimum temperature for growth at around 10 degrees C. However, psychrophily in the Antarctic Chlorella was not linked to high levels of membrane-associated poly-unsaturated fatty acids. Unlike the model Antarctic lake alga, Chlamydomonas raudensis UWO241, Chlorella BI has retained the ability for dynamic short term adjustment of light energy distribution between photosystem II (PS II) and photosystem I (PS I). In addition, Chlorella BI can grow under a variety of trophic modes, including heterotrophic growth in the dark. Thus, this newly isolated photopsychrophile has retained a higher versatility in response to environmental change than other well studied cold-adapted chlorophytes. 相似文献
3.
The deep-sea hydrothermal vents are located along the volcanic ridges and are characterized by extreme conditions such as unique physical properties (temperature, pression), chemical toxicity, and absence of photosynthesis. However, life exists in these particular environments. The primary producers of energy and organic molecules in these biotopes are chimiolithoautotrophic bacteria. Many animals species live in intimate and complex symbiosis with these sulfo-oxidizing and methanogene bacteria. These symbioses imply a strategy of nutrition and a specific metabolic organization involving numerous interactions and metabolic exchanges, between partners. The organisms of these ecosystems have developed different adaptive strategies. In these environments many microorganisms are adapted to high temperatures. Moreover to survive in these environments, living organisms have developed various strategies to protect themselves against toxic molecules such as H2S and heavy metals. 相似文献
4.
Growing Phototrophic Cells without Light 总被引:8,自引:0,他引:8
Many phototrophic microorganisms contain large quantities of high-value products such as n-3 polyunsaturated fatty acids and carotenoids but phototrophic growth is often slow due to light limitation. Some phototrophic
microorganisms can also grow on cheap organic substrate heterotrophically. Heterotrophic cultivation can be well controlled
and provides the possibility to achieve fast growth and high yield of valuable products on a large scale. Several strategies
have been investigated for cultivation of phototrophic microorganisms without light. These include trophic conversion of obligate
photoautotrophic microorganisms by genetic engineering, development of efficient cultivation systems and optimization of culture
conditions. This paper reviews recent advances in heterotrophic cultivation of phototrophic cells with an emphasis on microalgae. 相似文献
5.
Jenna M. Dolhi Denis P. Maxwell Rachael M. Morgan-Kiss 《Extremophiles : life under extreme conditions》2013,17(5):711-722
Permanently cold habitats dominate our planet and psychrophilic microorganisms thrive in cold environments. Environmental adaptations unique to psychrophilic microorganisms have been thoroughly described; however, the vast majority of studies to date have focused on cold-adapted bacteria. The combination of low temperatures in the presence of light is one of the most damaging environmental stresses for a photosynthetic organism: in order to survive, photopsychrophiles (i.e. photosynthetic organisms adapted to low temperatures) balance temperature-independent reactions of light energy capture/transduction with downstream temperature-dependent metabolic processes such as carbon fixation. Here, we review research on photopsychrophiles with a focus on an emerging model organism, Chlamydomonas raudensis UWO241 (UWO241). UWO241 is a psychrophilic green algal species and is a member of the photosynthetic microbial eukaryote community that provides the majority of fixed carbon for ice-covered lake ecosystems located in the McMurdo Dry Valleys, Antarctica. The water column exerts a range of environmental stressors on the phytoplankton community that inhabits this aquatic ecosystem, including low temperatures, extreme shade of an unusual spectral range (blue-green), high salinity, nutrient deprivation and extremes in seasonal photoperiod. More than two decades of work on UWO241 have produced one of our most comprehensive views of environmental adaptation in a cold-adapted, photosynthetic microbial eukaryote. 相似文献
6.
7.
Margesin R 《Journal of microbiology (Seoul, Korea)》2007,45(4):281-285
Cold environments, including polar and alpine regions, are colonized by a wide diversity of microorganisms able to thrive at low temperatures. There is evidence of a wide range of metabolic activities in alpine cold ecosystems. Like polar microorganisms, alpine microorganisms play a key ecological role in their natural habitats for nutrient cycling, litter degradation, and many other processes. A number of studies have demonstrated the capacity of alpine microorganisms to degrade efficiently a wide range of hydrocarbons, including phenol, phenol-related compounds and petroleum hydrocarbons, and the feasibility of low-temperature bioremediation of European alpine soils by stimulating the degradation capacity of indigenous microorganisms has also been shown. 相似文献
8.
9.
Huisman J Matthijs HC Visser PM Balke H Sigon CA Passarge J Weissing FJ Mur LR 《Antonie van Leeuwenhoek》2002,81(1-4):117-133
Light is the energy source that drives nearly all ecosystems on planet Earth. Yet, light limitation is still poorly understood.
In this paper, we present an overview of the principles of the light-limited chemostat. The theory for light-limited chemostats
differs considerably from the standard theory for substrate-limited chemostats. In particular, photons cannot be mixed by
vigorous stirring, so that phototrophic organisms experience the light-limited chemostat as a heterogeneous environment. Similar
to substrate-limited chemostats, however, light-limited chemostats do reach a steady state. This allows the study of phototrophic
microorganisms under well-controlled light conditions, at a constant specific growth rate, for a prolonged time. The theory
of the light-limited chemostat is illustrated with several examples from laboratory experiments, and a variety of ecological
applications are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Light-acclimation processes are central to allowing photosynthesis in aquatic ecosystems to span from high light conditions,
that are 10-fold higher than the light levels required to saturate photosynthesis, to the deep sea with extremely low light
levels. In dim light systems, nutrient levels are often high, and cells maximize the absorption of light by increasing the
cellular pool of pigments. The upper limits of light absorption are constrained by the package effect, which ultimately restricts
the benefit of the light absorption associated with an increase in cellular pigmentation, thus decreasing the cost/benefit
ratio relative to the metabolic cost of manufacturing cellular light-harvesting pigments. At extremely low light levels in
the deep sea, chloroplasts are sequestered in numerous organisms; however, these species are not obligate autotrophs and supplement
a heterotrophic/mixotrophic existence with opportunistic autotrophy. While low light acclimation is based on maximizing light
absorption, photosynthetic systems under high light, in addition to decreased light-harvesting cross sections, rely on energy-dissipation
processes to avoid light-induced damage to the photosynthetic apparatus and other free radical susceptible cell structures.
Dissipation of excess light energy represents the largest sink of the absorbed light in high light environments; however,
these processes remain largely unstudied and are rarely quantified. Cells supplement their energy-dissipation processes through
increasing the capacity to remove high-light-generated radicals and/or inducing vertical movement. Improved understanding
of strategies remains central for the understanding of algal distributions in nature and has broad industrial implications. 相似文献
11.
Coexistence of mixotrophs, autotrophs, and heterotrophs in planktonic microbial communities 总被引:1,自引:0,他引:1
We examine what circumstances allow the coexistence of microorganisms following different nutritional strategies, using a mathematical model. This model incorporates four nutritional types commonly found in planktonic ecosystems: (1) heterotrophic bacteria that consume dissolved organic matter and are prey to some of the other organisms; (2) heterotrophic zooflagellates that depend entirely on bacterial prey; (3) phototrophic algae that depend only on light and inorganic nutrients, and (4) mixotrophs that photosynthesize, take up inorganic nutrients, and consume bacterial prey. Mixotrophs are characterized by a parameter representing proportional mixing of phototrophic and heterotrophic nutritional strategies. Varying this parameter, a range of mixotrophic strategies was examined in hypothetical habitats differing in supplies of light, dissolved organic carbon, and dissolved inorganic phosphorous. Mixotrophs expressing a wide range of mixotrophic strategies persisted in model habitats with low phosphorus supply, but only those with a strategy that is mostly autotrophic persisted with high nutrient supply, and then only when light supply was also high. Organisms representing all four nutritional strategies were predicted to coexist in habitats with high phosphorus and light supplies. Coexistence involves predation by zooflagellates and mixotrophs balancing the high competitive ability of bacteria for phosphorus, the partitioning of partially overlapping resources between all populations, and possibly nonequlibrium dynamics. In most habitats, the strategy predicted to maximize the abundance of mixotrophs is to be mostly photosynthetic and supplement nutritional needs by consuming bacteria. 相似文献
12.
The cytoplasmic membrane of bacteria and archaea determine to a large extent the composition of the cytoplasm. Since the ion
and in particular the proton and/or the sodium ion electrochemical gradients across the membranes are crucial for the bioenergetic
conditions of these microorganisms, strategies are needed to restrict the permeation of these ions across their cytoplasmic
membrane. The proton and sodium permeabilities of all biological membranes increase with the temperature. Psychrophilic and
mesophilic bacteria, and mesophilic, (hyper)thermophilic and halophilic archaea are capable of adjusting the lipid composition
of their membranes in such a way that the proton permeability at the respective growth temperature remains low and constant
(homeo-proton permeability). Thermophilic bacteria, however, have more difficulties to restrict the proton permeation across their membrane at high temperatures and
these organisms have to rely on the less permeable sodium ions for maintaining a high sodium-motive force for driving their
energy requiring membrane-bound processes. Transport of solutes across the bacterial and archaeal membrane is mainly catalyzed
by primary ATP driven transport systems or by proton or sodium motive force driven secondary transport systems. Unlike most
bacteria, hyperthermophilic bacteria and archaea prefer primary ATP-driven uptake systems for their carbon and energy sources.
Several high-affinity ABC transporters for sugars from hyperthermophiles have been identified and characterized. The activities
of these ABC transporters allow these organisms to thrive in their nutrient-poor environments.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
Low-temperature extremophiles and their applications 总被引:32,自引:0,他引:32
Psychrophilic (cold-adapted) organisms and their products have potential applications in a broad range of industrial, agricultural and medical processes. In order for growth to occur in low-temperature environments, all cellular components must adapt to the cold. This fact, in combination with the diversity of Archaea, Bacteria and Eucarya isolated from cold environments, highlights the breadth and type of biological products and processes that might be exploited for biotechnology. Relative to this undisputed potential, psychrophiles and their products are under-utilised in biotechnology; however, recent advances, particularly with cold-active enzymes, herald rapid growth for this burgeoning field. 相似文献
14.
Cold adaptation of microorganisms 总被引:11,自引:0,他引:11
N J Russell 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1990,326(1237):595-608, discussion 608-11
Psychrophilic and psychrotrophic microorganisms are important in global ecology as a large proportion of our planet is cold (below 5 degrees C); they are responsible for the spoilage of chilled food and they also have potential uses in low-temperature biotechnological processes. Psychrophiles and psychrotrophs are both capable of growing at or close to zero, but the optimum and upper temperature limits for growth are lower for psychrophiles compared with psychrotrophs. Psychrophiles are more often isolated from permanently cold habitats, whereas psychrotrophs tend to dominate those environments that undergo thermal fluctuations. The molecular basis of psychrophily is reviewed in terms of biochemical mechanisms. The lower growth temperature limit is fixed by the freezing properties of dilute aqueous solutions inside and outside the cell. In contrast, the ability of psychrophiles and psychrotrophs to grow at low, but not moderate, temperatures depends on adaptive changes in cellular proteins and lipids. Changes in proteins are genotypic, and are related to the properties of enzymes and translation systems, whereas changes in lipids are genotypic or phenotypic and are important in regulating membrane fluidity and permeability. The ability to adapt their solute uptake systems through membrane lipid modulation may distinguish psychrophiles from psychrotrophs. The upper growth temperature limit can result from the inactivation of a single enzyme type or system, including protein synthesis or energy generation. 相似文献
15.
Henning Knoop Marianne Gründel Yvonne Zilliges Robert Lehmann Sabrina Hoffmann Wolfgang Lockau Ralf Steuer 《PLoS computational biology》2013,9(6)
Cyanobacteria are versatile unicellular phototrophic microorganisms that are highly abundant in many environments. Owing to their capability to utilize solar energy and atmospheric carbon dioxide for growth, cyanobacteria are increasingly recognized as a prolific resource for the synthesis of valuable chemicals and various biofuels. To fully harness the metabolic capabilities of cyanobacteria necessitates an in-depth understanding of the metabolic interconversions taking place during phototrophic growth, as provided by genome-scale reconstructions of microbial organisms. Here we present an extended reconstruction and analysis of the metabolic network of the unicellular cyanobacterium Synechocystis sp. PCC 6803. Building upon several recent reconstructions of cyanobacterial metabolism, unclear reaction steps are experimentally validated and the functional consequences of unknown or dissenting pathway topologies are discussed. The updated model integrates novel results with respect to the cyanobacterial TCA cycle, an alleged glyoxylate shunt, and the role of photorespiration in cellular growth. Going beyond conventional flux-balance analysis, we extend the computational analysis to diurnal light/dark cycles of cyanobacterial metabolism. 相似文献
16.
Michelle Liberton Aaron M. Collins Lawrence E. Page William B. O’Dell Hugh O’Neill Volker S. Urban Jerilyn A. Timlin Himadri B. Pakrasi 《Photosynthesis research》2013,118(1-2):17-24
Photosynthetic organisms rely on antenna systems to harvest and deliver energy from light to reaction centers. In fluctuating photic environments, regulation of light harvesting is critical for a photosynthetic organism’s survival. Here, we describe the use of a suite of phycobilisome mutants to probe the consequences of antenna truncation in the cyanobacterium Synechocystis sp. PCC 6803. Studies using transmission electron microscopy (TEM), hyperspectral confocal fluorescence microscopy (HCFM), small-angle neutron scattering (SANS), and an optimized photobioreactor system have unraveled the adaptive strategies that cells employ to compensate for antenna reduction. As the phycobilisome antenna size decreased, changes in thylakoid morphology were more severe and physical segregation of the two photosystems increased. Repeating distances between thylakoid membranes measured by SANS were correlated with TEM data, and corresponded to the degree of phycobilisome truncation. Thylakoid membranes were found to have a high degree of structural flexibility, and changes in the membrane system upon illumination were rapid and reversible. Phycobilisome truncation in Synechocystis 6803 reduced the growth rate and lowered biomass accumulation. Together, these results lend a dynamic perspective to the intracellular membrane organization in cyanobacteria cells and suggest an adaptive mechanism that allows cells to adjust to altered light absorption capabilities, while highlighting the cell-wide implications of antenna truncation. 相似文献
17.
Franz Brümmer Martin Pfannkuchen Alexander Baltz Vera Thiel 《Journal of experimental marine biology and ecology》2008,367(2):61-64
Sponges are the most basal metazoan organisms. As sessile filter feeders in marine or freshwater habitats, they often live in close association with phototrophic microorganisms. Active photosynthesis by the associated microorganisms has been believed to be restricted to the outer tissue portion of the sponge hosts. However, phototrophic microorganisms have also been detected in deeper tissue regions. In many cases they are found around spicules, siliceous skelettal elements of demosponges and hexactinellids. The finding of phototrophic organisms seemingly assembled around spicules led to the hypothesis of a siliceous light transmission system in sponges. The principle ability to conduct light was already shown for sponge derived, explanted spicules. However it was not shown until now, that in deed sponges have a light transmission system, and can harbour photosynthetically active microorganisms in deeper tissue regions.Here we show for the first time, that, as hypothesized 13 year ago, sponge spicules in living specimens transmit light into deeper tissue regions. Our results demonstrate that in opposite to the actual opinion, photosynthetically active microorganisms can also live in deeper tissue regions, and not only directly beneath the surface, when a light transmission system (spicules) is present.Our results show the possibility of massive or globular sponges being supplied with photosynthetic products or pathways throughout their whole body, implying not only a more important role of these endobioses. Our findings also elucidate the in-situ function of a recently more and more interesting biomaterial, which is unique not only for its mechanical, electrical and optical properties. Biosilica is of special interest for the possibility to produce it enzymatically under environmental conditions. 相似文献
18.
Psychrophilic enzymes: hot topics in cold adaptation 总被引:4,自引:0,他引:4
More than three-quarters of the Earth's surface is occupied by cold ecosystems, including the ocean depths, and polar and alpine regions. These permanently cold environments have been successfully colonized by a class of extremophilic microorganisms that are known as psychrophiles (which literally means cold-loving). The ability to thrive at temperatures that are close to, or below, the freezing point of water requires a vast array of adaptations to maintain the metabolic rates and sustained growth compatible with life in these severe environmental conditions. 相似文献
19.
Litvín Radek Bína David Herbstová Miroslava Pazderník Marek Kotabová Eva Gardian Zdenko Trtílek Martin Prášil Ondřej Vácha František 《Photosynthesis research》2019,142(2):137-151
Photosynthesis Research - Survival of phototrophic organisms depends on their ability to collect and convert enough light energy to support their metabolism. Phototrophs can extend their absorption... 相似文献