Transcript Cyanobacteria: systematic characters

CYANOBACTERIA (CHLOROXYBACTERIA)
BLUE GREEN ALGAE OR BLUE GREEN BACTERIA
Classified both under International Code of Botanical
Nomenclature (ICBN) and under Bacterial Code of
Nomenclature
Traditionally:
1. Order Chroococcales
2. Order Oscillatoriales
3. Order Nostocales
4. Order Stigonematales
Text book
1. Unicellular and colonial CB lacking
specialized cells or reproductive processes
2. Filamentous CB, lacking spores, heterocytes
or akinets
3. Exospore producing CB
4. Endospore producing CB
5. Heterocyte and akinete producing CB
6. True branching CB
Cyanobacteria: distribution and numbers
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 thermal
pools (ca. 70 °C),hypersaline waters etc.
•In symbioses, ca 8 % of lichens with cyanobacteria
as fycobiont + some with cephalodes (N2-fixation)
•In blooms (vannblomst) = mass occurrence with
surface scum and often toxin producing species
Why treat cyanobacteria
together with the algae?
1. Oxygenic photosynthesis and
pigments (chlorophyll a) as in algae
and plants
light
CO2 +2H2O chlorophyll a (CH2O) + O2 +H2O
All other photosynthetic bacteria (e.g. green sulfurbacteria)
have bacterial chlorophyll and anoxic photosynthesis
CO2 +2H2S
light
(CH2O) + 2S + H2O
Bacterial chlorophyll
Why treat cyanobacteria
together 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 cyanobacteria
together with the algae?
3. Algal (and plant) chloroplasts originated from primary
endosymbiosis between heterotrophic eukaryote and a free
living cyanobacterium
nucleus
Cyanobacterium taken up
by phagotrophic eukaryote
and eventually transformed
into a chloroplast
chloroplast
cyanobacterium
Cyanobacteria: evolutionary history
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 chloroplasts
ca. 1600 million years ago
Cyanobacteria: general characteristics
As all Prokaryotes absence of organelles:
- Nucleus
- Chloroplasts
- Mitochondria
- Golgi bodies (dictyosomes)
- Endoplasmatic reticulum (ER)
Cyanobacteria: general characteristics
Pigments:
chlorophyll a
(three genera with chlorophyll a + b)
phycobilins
phycoerythrin
phycocyanin
allophycocyanin
carotenoids
A variety, some are
specific, others as in
algae and plants
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
Ultra structure:
Thylakoids with phycobilisomes
Cyanobacteria: general characteristics
Cell wall: as Gram-negative
bacteria
central layer: murein
(peptidoglykan)
Outside the cell wall a ± thick layer of
polysaccharides 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
mucilaginous
sheath
trichome
filament = trichome + sheath
Cyanobacteria: systematic characters
Morphology
Unicellular
as colonies
single cells
free living
attached
(Order Chroococcales)
(cells polar)
Cyanobacteria: systematic characters
Morphology
Multicellular (filamentous)
uniseriate trichome
multiseriate trichome
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
Cyanobacteria: systematic characters
Vegetative reproduction:
by hormogonia, only in some
filamentous forms
hormogonium
Oscillatoria
“separation discs”
(necridia)
Lyngbya
Cyanobacteria: systematic characters
Vegetative reproduction:
Akinetes: resting cells with thick cell walls
and enriched with storage products
Anabaena
Akinetes may survive for years in darkness and under dry conditions
Cyanobacteria: systematic characters
Asexual reproduction:
Formation of spores, only in some
unicellular forms
exospores
endospores
(= baeocytes)
Dermocarpa
Chamaesiphon
Cyanobacteria: systematic characters
Sexual reproduction by gametes:
completely absent
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
nitrogenase
NH4+
intercalary heterocyst
terminal heterocyst
akinete
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
cephalodia in som lichens in addition to algal fykobiont
Marine plankton:
Richela intracellularis
N2 fixation endophytic in the diatom
Rhizosolenia 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
Nodularia spumigena Baltic Sea- Kattegat
Cyanobacteria: Traditional taxonomic
classification in orders
1. Order Chroococcales
Unicells, as individual cells or
colonies. Spores may occur,
never akinetes or heterocysts
2. Order Oscillatoriales
Uniseriate trichomes, never
akinetes or heterocysts
unbranched or false-braching
3. Order Nostocales
Uniseriate trichomes, with
akinetes and heterocysts.
Unbranched or false-braching
4. Order Stigonematales
Uni- or multiseriate trichomes,
with akinetes and heterocysts.
True branching
Phylogeny based on multiple sources
Microcystis aeruginosa
Toxin producing
cyanobacterium in
eutrophic fresh waters.
Toxin (microcystin) a
cyclic polypeptide that
cause liver damage
(hepatotoxin).
Other species produce alkaloids that are neurotoxins (anatoxin), Anabaena
and others
Skin 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).
Marine, benthic habitats
Mud flat (Sandspollen, Oslofjord) “microbial mats” Microcoleus
chtonoplastes - Lyngya aestuarii association
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 coast
and Oslofjord (based on data from Lindstedt,1943 and Wiik, 1981)
Microcoleus chtonoplastes
100
Microcoleus
Lyngbya aestuarii
85
Lyngbya
Spirulina subsalsa
85
Spirulina
Chroococcus turgidus
50
Chroococcus
Anabaena variabilis
50
Anabaena
Merismopedia glauca
40
Merismopedia
Microcoleus chtonoplastes + Lyngbya aestuarii
Microcoleus chtonoplastes
Lyngbya aestuarii
ALGAS BENTÓNICAS MARINAS DE GALICIA: Iconografías
Facultad de Ciencias, Universidad de A Coruña, I. Bárbara 2006
Black supralittoral zone consisting of Calothrix scopulorum and other
cyanobacteria plus the crustose black lichen Verrucaria maura.
Calothrix scopulorum
Cosmopolitan in
distribution.
hormogonium
attenuated trichomes
terminal heterocysts
Species composition in the Calothrix scopulorum associasjonen
Frequency of the 6 on top species based on 18 localities from Swedish west coast
and Norwegian coast to Tromsø (based on Lindstedt, 1943 and Wiik, 1983)
Calothrix scopulorum
100
diam 20 m
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
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