CYANOBACTERIA (CHLOROXYBACTERIA) BLUE GREEN ALGAE OR BLUE GREEN BACTERIA Traditionally: 1.Order...
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Transcript of CYANOBACTERIA (CHLOROXYBACTERIA) BLUE GREEN ALGAE OR BLUE GREEN BACTERIA Traditionally: 1.Order...
CYANOBACTERIA (CHLOROXYBACTERIA)BLUE GREEN ALGAE OR BLUE GREEN BACTERIA
Traditionally:1. Order Chroococcales2. Order Oscillatoriales3. Order Nostocales4. Order Stigonematales
Classified both under International Code of Botanical Nomenclature (ICBN) and under Bacterial Code of Nomenclature
Text book1. Unicellular and colonial CB lacking
specialized cells or reproductive processes2. Filamentous CB, lacking spores, heterocytes
or akinets 3. Exospore producing CB4. Endospore producing CB5. Heterocyte and akinete producing CB6. True branching CB
Cyanobacteria: distribution and numbers
•In blooms (vannblomst) = mass occurrence with surface scum and often toxin producing species
Include ca. 200 genera and 2000 species
All kinds of environments i.e. “ubiquitous”, mostly aquatic (rarely at pH< 4-5),terrestrial on rocks and soils,deserts, polar regions, other extreme habitats as thermalpools (ca. 70 °C),hypersaline waters etc.
•In symbioses, ca 8 % of lichens with cyanobacteria as fycobiont + some with cephalodes (N2-fixation)
Why treat cyanobacteriatogether with the algae?
1. Oxygenic photosynthesis and pigments (chlorophyll a) as in algae and plants
CO2 +2H2O (CH2O) + O2 +H2Olight
chlorophyll a
All other photosynthetic bacteria (e.g. green sulfurbacteria)have bacterial chlorophyll and anoxic photosynthesis
CO2 +2H2Slight
Bacterial chlorophyll
(CH2O) + 2S + H2O
Why treat cyanobacteriatogether with the algae?
2. Cyanobacteria (blue greens) occur with algae in similar habitats, mainly aquatic environments.
Similar ecological function (as primary producers). Together with the algae they stand for ca. 40 % of global primary production
Why treat cyanobacteriatogether with the algae?
3. Algal (and plant) chloroplasts originated from primary endosymbiosis between heterotrophic eukaryote and a free living cyanobacterium
Cyanobacterium taken upby phagotrophic eukaryoteand eventually transformedinto a chloroplast
cyanobacterium
chloroplast
nucleus
Oldest photosynthetic organisms, oldest fossil records ca. 3500 million years
Dominant form of life on Earth 1500 - 600 million years before present (BP) (e.g stromatolites)
Photosynthesis resulted in a gradual increase of O2 in the atmosphere
Primary endosymbiosis lead to algal chloroplastsca. 1600 million years ago
Cyanobacteria: evolutionary history
Cyanobacteria: general characteristics
As all Prokaryotes absence of organelles:- Nucleus- Chloroplasts- Mitochondria- Golgi bodies (dictyosomes)- Endoplasmatic reticulum (ER)
Cyanobacteria: general characteristics
phycobilins
phycoerythrin
phycocyaninallophycocyanin
carotenoidsA variety, some arespecific, others as in algae and plants
Pigments:
chlorophyll a(three genera with chlorophyll a + b)
scytonemin - extra cellular, UV-shielding pigment
Cyanobacteria: general characteristics
Storage products:
- Cyanophycean-starch (-1,4 glucan)- Cyanophycin-grains: N-reserve, a
co-polymer of two amino acids (asparagine and arginine)
- Volutin grains - polyphosphate granules- Lipids
Cyanobacteria: general characteristics
Thylakoids with phycobilisomes
Ultra structure:
Cyanobacteria: general characteristics
central layer: murein (peptidoglykan)
Cell wall: as Gram-negativebacteria
mucilaginoussheath
trichome
Outside the cell wall a ± thick layer ofpolysaccharides and polypeptides may form a sheath in some filamentous forms. The sheath may be brownish in color, due to scytonemin (UV absorbing protecting pigment) The cell row itself is called trichome
filament = trichome + sheath
Cyanobacteria: systematic characters
Unicellular
single cellsas colonies
Morphology
(Order Chroococcales)attached(cells polar)
free living
Cyanobacteria: systematic characters
Multicellular (filamentous)
uniseriate trichome
multiseriate trichome
Morphology
Cyanobacteria: systematic characters
False branching
Cyanobacteria: systematic characters
True branching
only in some representatives of the order Stigonematales
Orden Stigonematales(no marine representatives
Stigonema
Cyanobacteria: systematic characters
Vegetative reproduction:by binary division and fragmentation
Chroococcus Merismopedia
“separation discs” (necridia)
Cyanobacteria: systematic characters
by hormogonia, only in some filamentous forms
Oscillatoria
Vegetative reproduction:
hormogonium
Lyngbya
Cyanobacteria: systematic characters
Akinetes: resting cells with thick cell wallsand enriched with storage products
Anabaena
Vegetative reproduction:
Akinetes may survive for years in darkness and under dry conditions
Cyanobacteria: systematic characters
Formation of spores, only in someunicellular forms
exosporesendospores(= baeocytes)
Dermocarpa Chamaesiphon
Asexual reproduction:
Cyanobacteria: systematic characters
completely absentSexual reproduction by gametes:
Viral transduction may happen
Cyanobacteria: systematic characters
Heterocytes (heterocysts) are cells with nitrogen fixation as a special function.Heterocytes only present in some filamentous forms (Nostocales, Stigonematales), though N-fixation may occur also in some non- heterocysteous forms
N2 nitrogenaseNH4
+
intercalary heterocyst akinete
terminal heterocyst
Cyanobacterial nitrogen fixation of great ecological and commercial importance
Rice agriculture:Azolla-Anabaena system 120-310 kg N per hectar per year. Free-living cyanobacteria e.g. Tolypella or Anabaena ca 40 kg See: Vaishampayan et al. (2001) Cyanobacterial Biofertilizers in Rice Agriculture - Bot.Rev. 67 (4): 453-516
Marine plankton:Richela intracellularis
N2 fixation endophytic in the diatomRhizosolenia sp.
Trichodesmium erythraeum - in tropical marine plankton, Oscillatoria-like trichoms as free floating bundles. May fix up to 30 mg nitrogen m-2 day-1
cephalodia in som lichens in addition to algal fykobiont
Nodularia spumigena -Baltic Sea- Kattegat
Cyanobacteria: Traditional taxonomicclassification in orders
Unicells, as individual cells orcolonies. Spores may occur, never akinetes or heterocysts
1. Order Chroococcales
Uniseriate trichomes, never akinetes or heterocystsunbranched or false-braching
2. Order Oscillatoriales
3. Order Nostocales
4. Order Stigonematales
Uniseriate trichomes, withakinetes and heterocysts.
Unbranched or false-braching
Uni- or multiseriate trichomes, with akinetes and heterocysts.True branching
Phylogeny based on multiple sources
Microcystis aeruginosa
Toxin producingcyanobacterium in eutrophic fresh waters.Toxin (microcystin) acyclic polypeptide thatcause liver damage(hepatotoxin).
Other species produce alkaloids that are neurotoxins (anatoxin), Anabaena and othersSkin irritants (e.g. Lyngbya majuscula)Other secondary metabolites may cause smell and odors to drinking water (geosmin)
“Vannblomst” = bloom of Microcystis aeruginosa forming surface scum (Frøylandsvatnet, Jæren).
Mud flat (Sandspollen, Oslofjord) “microbial mats” Microcoleus chtonoplastes - Lyngya aestuarii association
Marine, benthic habitats
Film of cyanobacteria on shallow,
muddy bottom(Inner Oslofjord,Frognerkilen)
Species composition in the Microcoleus - Lyngbya association Frequency of the 6 on top species based on 13 localities from Swedish west coastand Oslofjord (based on data from Lindstedt,1943 and Wiik, 1981)
Microcoleus chtonoplastes 100
Lyngbya aestuarii 85
Spirulina subsalsa 85
Chroococcus turgidus 50
Anabaena variabilis 50
Merismopedia glauca 40
Microcoleus
Lyngbya
Spirulina
Chroococcus
Merismopedia
Anabaena
Microcoleus chtonoplastes + Lyngbya aestuarii
Microcoleus chtonoplastes
ALGAS BENTÓNICAS MARINAS DE GALICIA: Iconografías
Facultad de Ciencias, Universidad de A Coruña, I. Bárbara 2006
Lyngbya aestuarii
Black supralittoral zone consisting of Calothrix scopulorum and other cyanobacteria plus the crustose black lichen Verrucaria maura.
Calothrix scopulorum
terminal heterocysts
hormogonium
Cosmopolitan in distribution.
attenuated trichomes
Species composition in the Calothrix scopulorum associasjonenFrequency of the 6 on top species based on 18 localities from Swedish west coastand Norwegian coast to Tromsø (based on Lindstedt, 1943 and Wiik, 1983)
Calothrix scopulorum 100
Phormidium fragile 100 (Leptolyngbya fragilis)
Plectonema battersii 95(Pseudophormidium battersii)
Gloeocapsa crepidinum 80
Plectonema norvegicum 75
Microcystis minuta 60
diam 1.2 - 2.5 m
diam 2 - 3.5 m
diam 20 m
Other marine habitats and species.
Epiphytically, on various macroalgae: Calothrix confervicola, Dermocarpa sp.
Endophytically, Calothrix parasitica (in Nemalion)
In shells, Hyella caespitosa, Plectonema terebrans, Mastigocoleus testarum
Epilithic, Rivularia atra
Marine plankton, Synechocystis, shaerical cells, 2-6 m Synechococcus, cylindrical cells, 1.5 - 5 m Prochlorococcus, as Synechococcus, lacks phycoblins, has chl. a+b Nodularia spumigena (Baltic Sea, brackish water) Trichodesmium thiebautii, Oscillatoria like trochomes in bundles Trichodesmium erythraeum, mainly tropical waters