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


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


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)


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


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


Thylakoids with phycobilisomes

Ultra structure:


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


Multicellular (filamentous)

uniseriate trichome

multiseriate trichome

Morphology


False branching


True branching

only in some representatives of the order Stigonematales

Orden Stigonematales(no marine representatives

Stigonema


Vegetative reproduction:by binary division and fragmentation

Chroococcus Merismopedia

“separation discs” (necridia)


by hormogonia, only in some filamentous forms

Oscillatoria

Vegetative reproduction:

hormogonium

Lyngbya


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


Formation of spores, only in someunicellular forms

exosporesendospores(= baeocytes)

Dermocarpa Chamaesiphon

Asexual reproduction:


completely absentSexual reproduction by gametes:

Viral transduction may happen


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

cyanobacteria (chloroxybacteria) blue green algae or blue green bacteria traditionally: 1.order...

Documents

general characteristicsas

pigments chlorophyll

primary producers

chlorophyll athree genera

cyanobacteria blue greens

similar habitats

aquatic environments

global primary productionwhy