Skip to Content.
Sympa Menu

permaculture - [permaculture] Cyanobacteria - Wikipedia

permaculture@lists.ibiblio.org

Subject: permaculture

List archive

Chronological Thread  
  • From: Lawrence London <lfljvenaura@gmail.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: [permaculture] Cyanobacteria - Wikipedia
  • Date: Sun, 18 Feb 2018 02:02:09 -0500

Cyanobacteria - Wikipedia
https://en.wikipedia.org/wiki/Cyanobacteria

*Cyanobacteria* /saɪˌænoʊbækˈtɪəriə/
<https://en.wikipedia.org/wiki/Help:IPA/English>, also known as *Cyanophyta*,
are a phylum <https://en.wikipedia.org/wiki/Phylum_%28biology%29> of
bacteria <https://en.wikipedia.org/wiki/Bacteria> that obtain their energy
through photosynthesis <https://en.wikipedia.org/wiki/Photosynthesis>,[4]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-4> and are the only
photosynthetic prokaryotes <https://en.wikipedia.org/wiki/Prokaryote> able
to produce oxygen <https://en.wikipedia.org/wiki/Oxygen>.[5]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-5> The name
"cyanobacteria" comes from the color of the bacteria (Greek
<https://en.wikipedia.org/wiki/Greek_language>: κυανός, translit.
<https://en.wikipedia.org/wiki/Romanization_of_Greek> *kyanós*, lit.
<https://en.wikipedia.org/wiki/Literal_translation> 'blue').[6]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-6>[7]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-7> Cyanobacteria
(which are prokaryotes) used to be called "blue-green algae". They have
been renamed 'cyanobacteria' in order to avoid the term "algae
<https://en.wikipedia.org/wiki/Algae>", which in modern usage is restricted
to eukaryotes <https://en.wikipedia.org/wiki/Eukaryote>.[8]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Allaby_92-8>

Unlike heterotrophic <https://en.wikipedia.org/wiki/Heterotroph>
prokaryotes, cyanobacteria have internal membranes. They are flattened sacs
called thylakoids <https://en.wikipedia.org/wiki/Thylakoids> where
photosynthesis is performed.[9]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-9>[10]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-10>

Phototrophic <https://en.wikipedia.org/wiki/Phototroph> eukaryotes perform
photosynthesis by plastids <https://en.wikipedia.org/wiki/Plastid> that
have their ancestry in cyanobacteria, via a process called endosymbiosis
<https://en.wikipedia.org/wiki/Endosymbiosis>. These endosymbiotic
cyanobacteria in eukaryotes have evolved or differentiated into specialized
organelles <https://en.wikipedia.org/wiki/Organelle> such as chloroplasts
<https://en.wikipedia.org/wiki/Chloroplast>, etioplasts
<https://en.wikipedia.org/wiki/Etioplast> and leucoplasts
<https://en.wikipedia.org/wiki/Leucoplast>.

By producing and releasing oxygen (as a byproduct of photosynthesis),
cyanobacteria are thought to have converted the early oxygen-poor, reducing
atmosphere <https://en.wikipedia.org/wiki/Reducing_atmosphere> into an
oxidizing <https://en.wikipedia.org/wiki/Redox> one, causing the Great
Oxygenation Event <https://en.wikipedia.org/wiki/Great_Oxygenation_Event>
and the "rusting of the Earth",[11]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Whitton2012-11>
which dramatically changed the composition of the Earth's life forms and
led to the near-extinction of anaerobic organisms
<https://en.wikipedia.org/wiki/Anaerobic_organism>.


Description

Cyanobacteria are a group of photosynthetic, nitrogen-fixing
<https://en.wikipedia.org/wiki/Nitrogen-fixing> bacteria that live in a
wide variety of moist soils and water either freely or in a symbiotic
relationship with plants or lichen
<https://en.wikipedia.org/wiki/Lichen>-forming
fungi <https://en.wikipedia.org/wiki/Fungus> (as in the lichen genus
*Peltigera
<https://en.wikipedia.org/wiki/Peltigera>*).[12]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-12> They range from
unicellular <https://en.wikipedia.org/wiki/Unicellular_organism> to
filamentous <https://en.wikipedia.org/wiki/Filamentation> and include
colonial <https://en.wikipedia.org/wiki/Colony_%28biology%29> species.
Colonies may form filaments, sheets, or even hollow spheres. Some
filamentous species can differentiate into several different cell
<https://en.wikipedia.org/wiki/Cell_%28biology%29> types: *vegetative cells*
– the normal, photosynthetic cells that are formed under favorable growing
conditions; *akinetes <https://en.wikipedia.org/wiki/Akinete>* –
climate-resistant spores that may form when environmental conditions become
harsh; and thick-walled *heterocysts
<https://en.wikipedia.org/wiki/Heterocysts>* – which contain the enzyme
nitrogenase <https://en.wikipedia.org/wiki/Nitrogenase>, vital for nitrogen
fixation <https://en.wikipedia.org/wiki/Nitrogen_fixation>[13]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-13>[14]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Golden_1998-14>[15]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Fay_1992-15> in an
anaerobic environment due to its sensitivity to oxygen.[15]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Fay_1992-15>
Nitrogen fixation

Cyanobacteria can fix atmospheric nitrogen
<https://en.wikipedia.org/wiki/Nitrogen> in anaerobic conditions by means
of specialized cells called heterocysts
<https://en.wikipedia.org/wiki/Heterocyst>.[14]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Golden_1998-14>[15]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Fay_1992-15>
Heterocysts may also form under the appropriate environmental conditions
(anoxic) when fixed nitrogen is scarce. Heterocyst-forming species are
specialized for nitrogen fixation and are able to fix nitrogen gas into
ammonia <https://en.wikipedia.org/wiki/Ammonia> (NH3
<https://en.wikipedia.org/wiki/Ammonia>), nitrites
<https://en.wikipedia.org/wiki/Nitrites> (NO−
2 <https://en.wikipedia.org/wiki/Nitrite>) or nitrates
<https://en.wikipedia.org/wiki/Nitrates> (NO−
3 <https://en.wikipedia.org/wiki/Nitrate>), which can be absorbed by plants
and converted to protein and nucleic acids (atmospheric nitrogen is not
bioavailable <https://en.wikipedia.org/wiki/Bioavailable> to plants, except
for those having endosymbiotic nitrogen-fixing bacteria
<https://en.wikipedia.org/wiki/Nitrogen-fixing_bacteria>, especially the
Fabaceae <https://en.wikipedia.org/wiki/Fabaceae> family, among others).

Free-living cyanobacteria are present in the water of rice paddies
<https://en.wikipedia.org/wiki/Paddy_field>, and cyanobacteria can be found
growing as epiphytes <https://en.wikipedia.org/wiki/Epiphyte> on the
surfaces of the green alga, *Chara
<https://en.wikipedia.org/wiki/Chara_%28alga%29>*, where they may fix
nitrogen.[16] <https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-16>
Cyanobacteria such as *Anabaena <https://en.wikipedia.org/wiki/Anabaena>*
(a symbiont of the aquatic fern *Azolla
<https://en.wikipedia.org/wiki/Azolla>*), can provide rice plantations with
biofertilizer <https://en.wikipedia.org/wiki/Biofertilizer>.[17]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Azolla-Anabaena_as_a_Biofertilizer_for_Rice_Paddy_Fields_in_the_Po_Valley,_a_Temperate_Rice_Area_in_Northern_Italy-17>


Ecology
<https://en.wikipedia.org/wiki/File:2010_Filamentous_Cyanobacteria_Bloom_near_Fiji.jpg>
Cyanobacterial bloom near Fiji <https://en.wikipedia.org/wiki/Fiji>

Cyanobacteria can be found in almost every terrestrial and aquatic habitat
<https://en.wikipedia.org/wiki/Aquatic_habitat>—oceans
<https://en.wikipedia.org/wiki/Ocean>, fresh water
<https://en.wikipedia.org/wiki/Fresh_water>, damp soil, temporarily
moistened rocks in deserts <https://en.wikipedia.org/wiki/Desert>, bare
rock and soil, and even Antarctic <https://en.wikipedia.org/wiki/Antarctic>
rocks. They can occur as planktonic
<https://en.wikipedia.org/wiki/Planktonic> cells or form phototrophic
biofilms <https://en.wikipedia.org/wiki/Phototrophic_biofilms>. They are
found in almost every endolithic ecosystem
<https://en.wikipedia.org/wiki/Endolithic_ecosystem>.[23]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-23> A few are
endosymbionts <https://en.wikipedia.org/wiki/Endosymbiont> in lichens
<https://en.wikipedia.org/wiki/Lichen>, plants, various protists
<https://en.wikipedia.org/wiki/Protist>, or sponges
<https://en.wikipedia.org/wiki/Sea_sponge> and provide energy for the host
<https://en.wikipedia.org/wiki/Host_%28biology%29>. Some live in the fur of
sloths <https://en.wikipedia.org/wiki/Sloth>, providing a form of camouflage
<https://en.wikipedia.org/wiki/Camouflage>.[24]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-24>

Aquatic cyanobacteria are known for their extensive and highly visible
blooms <https://en.wikipedia.org/wiki/Algal_bloom> that can form in both
freshwater <https://en.wikipedia.org/wiki/Freshwater> and marine
environments. The blooms can have the appearance of blue-green paint or
scum. These blooms can be toxic <https://en.wikipedia.org/wiki/Toxic>, and
frequently lead to the closure of recreational waters when spotted. Marine
bacteriophages <https://en.wikipedia.org/wiki/Marine_bacteriophage> are
significant parasites <https://en.wikipedia.org/wiki/Parasites> of
unicellular marine cyanobacteria.[25]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-25>

Cyanobacteria growth is favoured in ponds and lakes where waters are calm
and have less turbulent mixing.[26]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-JOHNK-26> Their life
cycles are disrupted when the water naturally or artificially mixes from
churning currents caused by the flowing water of streams or the churning
water of fountains. For this reason blooms of cyanobacteria seldom occur in
rivers unless the water is flowing slowly. Growth is also favored at higher
temperatures, making increasing water temperature as a result of global
warming <https://en.wikipedia.org/wiki/Global_warming> more problematic. At
higher temperatures Microcystis <https://en.wikipedia.org/wiki/Microcystis>
species are able to outcompete diatoms
<https://en.wikipedia.org/wiki/Diatoms> and green algae
<https://en.wikipedia.org/wiki/Green_algae>. This is a concern because of
the production of toxins produced by Microcystis.[26]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-JOHNK-26>

Based on environmental trends, models and observations suggest
cyanobacteria will likely increase their dominance in aquatic environments.
This can lead to serious consequences, particularly the contamination of
sources of drinking water <https://en.wikipedia.org/wiki/Drinking_water>.
Cyanobacteria can interfere with water treatment
<https://en.wikipedia.org/wiki/Water_treatment> in various ways, primarily
by plugging filters (often large beds of sand and similar media), and by
producing cyanotoxins <https://en.wikipedia.org/wiki/Cyanotoxin> which have
the potential to cause serious illness if consumed. Consequences may also
lie within fisheries and waste management practices. Anthropogenic
eutrophication <https://en.wikipedia.org/wiki/Eutrophication>, rising
temperatures, vertical stratification and increased atmospheric carbon
dioxide <https://en.wikipedia.org/wiki/Atmospheric_carbon_dioxide> are
contributors to cyanobacteria increasing dominance of aquatic ecosystems.
[27] <https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-27>

Cyanobacteria have been found to play an important role in terrestrial
habitats. It has been widely reported cyanobacteria soil crusts
<https://en.wikipedia.org/wiki/Soil_crust> help to stabilize soil to
prevent erosion <https://en.wikipedia.org/wiki/Erosion> and retain water.
[28] <https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-28> An example
of a cyanobacterial species that does so is *Microcoleus vaginatus*. *M.
vaginatus* stabilizes soil using a polysaccharide
<https://en.wikipedia.org/wiki/Polysaccharide> sheath that binds to sand
particles and absorbs water.[29]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-29>

Some of these organisms contribute significantly to global ecology and
the oxygen
cycle <https://en.wikipedia.org/wiki/Oxygen_cycle>. The tiny marine
cyanobacterium *Prochlorococcus
<https://en.wikipedia.org/wiki/Prochlorococcus>* was discovered in 1986 and
accounts for more than half of the photosynthesis of the open ocean.[30]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-30> Many
cyanobacteria even display the circadian rhythms
<https://en.wikipedia.org/wiki/Circadian_rhythm> that were once thought to
exist only in eukaryotic cells (see bacterial circadian rhythms
<https://en.wikipedia.org/wiki/Bacterial_circadian_rhythms>).

"Cyanobacteria are arguably the most successful group of microorganisms
<https://en.wikipedia.org/wiki/Microorganisms> on earth. They are the most
genetically diverse; they occupy a broad range of habitats across all
latitudes, widespread in freshwater, marine, and terrestrial ecosystems,
and they are found in the most extreme niches such as hot springs, salt
works, and hypersaline bays. Photoautotrophic
<https://en.wikipedia.org/wiki/Photoautotrophic>, oxygen-producing
cyanobacteria created the conditions in the planet's early atmosphere that
directed the evolution of aerobic metabolism and eukaryotic photosynthesis.
Cyanobacteria fulfill vital ecological functions in the world's oceans,
being important contributors to global carbon and nitrogen budgets." –
Stewart and Falconer[31]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-WalshSmith2011-31>

Photosynthesis

While contemporary cyanobacteria are linked to the plant kingdom
<https://en.wikipedia.org/wiki/Plant_kingdom> as descendants of the
endosymbiotic progenitor of the chloroplast
<https://en.wikipedia.org/wiki/Chloroplast>, there are several features
which are unique to this group.
Carbon fixation

Cyanobacteria use the energy of sunlight
<https://en.wikipedia.org/wiki/Sunlight> to drive photosynthesis
<https://en.wikipedia.org/wiki/Photosynthesis>, a process where the energy
of light is used to synthesize organic compounds
<https://en.wikipedia.org/wiki/Organic_compound> from carbon dioxide.
Because they are aquatic organisms, they typically employ several
strategies which are collectively known as a "carbon concentrating
mechanism" to aid in the acquisition of inorganic carbon (CO2 or bicarbonate
<https://en.wikipedia.org/wiki/Bicarbonate>). Among the more specific
strategies is the widespread prevalence of the bacterial microcompartments
known as carboxysomes <https://en.wikipedia.org/wiki/Carboxysome>.[32]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-KerfeldHeinhorst2010-32>
These icosahedral <https://en.wikipedia.org/wiki/Icosahedron> structures
are composed of hexameric shell proteins that assemble into cage-like
structures that can be several hundreds of nanometers in diameter. It is
believed that these structures tether the CO2-fixing enzyme, RuBisCO
<https://en.wikipedia.org/wiki/RuBisCO>, to the interior of the shell, as
well as the enzyme carbonic anhydrase
<https://en.wikipedia.org/wiki/Carbonic_anhydrase>, using the paradigm
of metabolic
channeling <https://en.wikipedia.org/wiki/Metabolic_channeling> to enhance
the local CO2 concentrations and thus increase the efficiency of the
RuBisCO enzyme.[33]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-LongBadger2007-33>


Earth history

Stromatolites <https://en.wikipedia.org/wiki/Stromatolites> are layered
biochemical accretionary
<https://en.wikipedia.org/wiki/Accretion_%28geology%29> structures
<https://en.wikipedia.org/wiki/Structure> formed in shallow water by the
trapping, binding, and cementation of sedimentary grains by biofilms
<https://en.wikipedia.org/wiki/Biofilm> (microbial mats
<https://en.wikipedia.org/wiki/Microbial_mat>) of microorganisms
<https://en.wikipedia.org/wiki/Microorganism>, especially cyanobacteria.[79]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-79>
<https://en.wikipedia.org/wiki/File:Stromatolites.jpg>
Stromatolites <https://en.wikipedia.org/wiki/Stromatolites> left behind by
cyanobacteria are the oldest known fossils of life on Earth. This
one-billion-year-old fossil is from Glacier National Park
<https://en.wikipedia.org/wiki/Glacier_National_Park_%28U.S.%29> in Montana.

During the Precambrian <https://en.wikipedia.org/wiki/Precambrian>,
stromatolite communities of microorganisms grew in most marine and
non-marine environments in the photic zone. After the Cambrian explosion of
marine animals, grazing on the stromatolite mats by herbivores greatly
reduced the occurrence of the stromatolites in marine environments. Since
then, they are found mostly in hypersaline conditions where grazing
invertebrates cannot live (e.g. Shark Bay
<https://en.wikipedia.org/wiki/Shark_Bay>, Western Australia).
Stromatolites provide ancient records of life on Earth by fossil remains
which might date from more than 3.5 Ga
<https://en.wikipedia.org/wiki/Annus#SI_prefix_multipliers> ago, but this
is disputed.[80]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-PiP-80> As of 2010
the oldest undisputed evidence of cyanobacteria is from 2.1 Ga ago, but
there is some evidence for them as far back as 2.7 Ga ago. Oxygen
<https://en.wikipedia.org/wiki/Oxygen> levels in the atmosphere remained
around or below 1% of today's level until 2.4 Ga ago (the Great Oxygenation
Event <https://en.wikipedia.org/wiki/Great_Oxygenation_Event>). The rise in
oxygen may have caused a fall in methane
<https://en.wikipedia.org/wiki/Methane> levels, and triggered the Huronian
glaciation <https://en.wikipedia.org/wiki/Huronian_glaciation> from around
2.4 to 2.1 Ga ago. In this way, cyanobacteria may have killed off much of
the other bacteria of the time.[81]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Lane-81>

Oncolites <https://en.wikipedia.org/wiki/Oncolite> are sedimentary
structures <https://en.wikipedia.org/wiki/Sedimentary_structures> composed
of oncoids, which are layered structures formed by cyanobacterial growth.
Oncolites are similar to stromatolites, but instead of forming columns,
they form approximately spherical structures that were not attached to the
underlying substrate as they formed.[82]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-Corsetti2003-82> The
oncoids often form around a central nucleus, such as a shell fragment,[83]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-83> and a calcium
carbonate <https://en.wikipedia.org/wiki/Calcium_carbonate> structure is
deposited by encrusting microbes <https://en.wikipedia.org/wiki/Microbes>.
Oncolites are indicators of warm waters in the photic zone
<https://en.wikipedia.org/wiki/Photic_zone>, but are also known in
contemporary freshwater environments.[84]
<https://en.wikipedia.org/wiki/Cyanobacteria#cite_note-84> These structures
rarely exceed 10 cm in diameter.



  • [permaculture] Cyanobacteria - Wikipedia, Lawrence London, 02/18/2018

Archive powered by MHonArc 2.6.24.

Top of Page