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Microbiology > Cyanobacteria > Flashcards

Cyanobacteria Flashcards

1
Q

2 dominant kinds of phototrophs based on their source of carbon

A
  • Photoautotrophs (fix CO2)
  • Photoheterotrophs (use organic carbon)
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2
Q

Cyanobacteria characterisitcs

A
  • gram negative
  • Mostly oxygenic photoautotrophs
  • Diverse morphologies
  • Account for 1/4 of all biomass production on earth
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3
Q

Prochlorococcus

A

single-celled cyanobacteria
* most abundant phototroph in oceans

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4
Q

What do Oscillatoria, Nostoc, and Anabaena all have in common

A

all filamentous bacteria

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5
Q

what are the spores called that many cyanobacteria form

A

akinetes

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6
Q

what was responsible for the Great Oxidation Event

A

Photosynthesis by Cyanobacteria

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7
Q

Great Oxidation Event

A

Start of the rapid oxidation of earths atmosphere - dramatic increase in oxygen on earth
* major changes in planet
* Oxygen was toxic to most microbes
* This led to first mass extinction

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8
Q

What structures are a major clue of the Great Oxidation Event

A

Stromatolites

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9
Q

Four major categories of prokaryotic microbes found in stromatolites

A
  1. Cyanobacteria
  2. prokaryotes of uncertain systematic relations (unsure)
  3. Sulphate-reducing bacteria
  4. Methane-producing archaeans
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10
Q

How does cell size and morphology of cyanobacteria compare to other prokaryotes

A

Have larger cells and more complex morphology = easier to recognize = best documented fossil records

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11
Q

2 different hypotheses about mutlicellularity and the GOE

A
  1. Multicellularity before the GOE due to high abundance of cyanobacteria = high O2
  2. Multicellualrity arose after GOE as asaptation to newly oxidized habitats
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12
Q

Conventional classification of cyanobacteria (section 1-5)

A

Section I: unicellular, binary fissuon
Section II: unicellular, binary/multiple dission, form baeocytes
Section III: filamentous, non-heterocystous
Section IV: filamentous, heterocysts devlop during nitrogen starvation
Section V: filamentous, in absense of nitrogenous source heterocysts develop

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13
Q

Example of Cyanobacteria classified as section I and why

A

Synechococcus sp. - can divide by binary fission

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14
Q

Example of Cyanobacteria classified as section II and why

A

Pleurocapsa sp. - divide by multiple fission and develop Baeocytes (small cell that will grow and become a vegetative cell)

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15
Q

Are cyanobacteria gram -

What might differentiate them

A

Yes and no..
* two membranes AND a thick peptidoglycan layer (S-layer like gram +)

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16
Q

What are cyanobacterial blooms

A
  • Harmful algal blooms”
  • happens in bodies of water
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17
Q

Three factors that help development of and maintaining bacterial blooms

A
  • factors concur to such cyanobacterial proliferation, such as high nitrogen and phosphorus content
  • light intensity and temperature trends (climate variations)
  • Eutrophication (excess of nutrients)
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18
Q

Nodularia spumigena and cyanobacteria blooms

A
  • type of cyanobacteria that creates blooms
  • more toxic when theres little nitrogen in the water but sufficient amount of phosphorus
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19
Q

What are cyanotoxins

A

“harmful agents” (e.g. Microcystin, Nodularins) produced by cyanobacteria
* they can be aljaloids, non-ribosomal peptides, polyketides, non-protein amino acids, indole alkaloids, oragnophosphates, lipopeptides, and lipoglycans

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20
Q

What do cyanotoxins provide to cyanbacteria

A

provide competitive advantage

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21
Q

how might organisms be exposed to cyanobacterial toxins

A

drinking, bathing in, or inhaling contaminated water

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22
Q

Consequences of exposure to cyanotoxins

A

inflammation, immune disorders, oxidative stress, and ROS

23
Q

Cyanotoxin abbreviated NOD

A

Nodularins
* pentapeptides (5 amino acids)

24
Q

What type of toxin in the cyanotoxin Nodularins (i.e. where in the body does it effect)

A

Hepatotoxin (liver)

25
Q

What cyanobacteria produces the toxin Nodularins

A

Nodularia Spumigena

26
Q

Stability of Nodularins (NODs)

A

very stable: it will not degrade as a result of light, temp, and microwaves

27
Q

What can we do to avoid contact with cyanotoxins

A
  • Monitoring via Satellite Imagery.
  • Cyanobacteria identification -> is it a cyanotoxin producer?
  • Cyanotoxin identification (i.e. ELISA, UHPLC, etc.)
  • Zonification is important. Avoid water contact.
  • Ensure adequate water treatment.
28
Q

Microbial mat

A

layered community of microorganisms found in aquatic environments

29
Q

Microbial mats are formed by multiple ____ of microorganisms embedded in a matrix of ________________, in a vertical fashion due to the physical gradients

A

biofilms; exopolysaccharides (EPS)

30
Q

Thickness of microbial mats

A

ranges from millimeters to several centimeters

31
Q

Microbial mats are commonly associated with what habitats

A

aquatic habitats, including hot springs, hypersaline ponds, and intertidal coastal zones and oligotrophic enviornments (low levels of nitrogen)

32
Q

Layers of microbial mats and what they do

A
  1. Scytonemin -> photoprotective pigment (UV radiation)
  2. Cyanobacteria -> photosynthesis
  3. Bacteria below cyanobacteria -> low O2 levels

layer of green sulphur bacteria has been observed in only a few occasions

33
Q

how do microbial mats work together

A
  • microorganisms interact and exchange signals
  • embedded in a matrix of exopolysaccharides and nutrients to enable a greater flow of resources and energy for the survival of the community
34
Q

Describe the layered community of a microbial mat (diagram from lecture) in respect to metabolic byproducts and the infiltration biofilms (EPSs)

A
  • Cyanobacteria = oxygenic phototrophs: use sunlight to convert carbon dioxide into organic matter (CH₂O) and oxygen
  • oxygen produced by cyanobacteria creates an aerobic zone that can be utilized by aerobic heterotrophs
  • Cyanobacterial organic material byproduct (CH2O) is used by aerobic heterotrophs, anoxygenic phototrophs, and anaerobic heterotrophs
35
Q

to avoid grazing where do microbial mats colonize? has it always been this way?

A

colonize in “extreme environments” - i.e. hot springs and hypersaline pools where the slow growing microbial mats wont be disrupted
* in the past they colonized in all places (stromatolites)

36
Q

Biocrusts

A

community of living organisms on the soil surface in arid or semi-arid systems

37
Q

What are biocrusts typically composed of

A

cyanobacteria, fungi, lichens, bryophytes, and algae

38
Q

ecological function of biocrusts

A

soil stability

39
Q

4 types of biocrusts

A
  • smooth/flat
  • Rugose
  • Pinnacled
  • Rolling
40
Q

Characteristics of smooth/flat biocrusts

A
  • dominated by cyanobacteria
  • hyperarid regions
  • high PET (potential evapo-transpiration)
  • Cannot support lichens or mosses (why its flat)
41
Q

Characteristics of rugose biocrusts

A
  • up to 3 cm
  • High PET deserts (potential evapo-transpiration)
  • Minimal lichen, moss coverage
42
Q

Characteristics of Pinnacled Biocrusts

A
  • up to 15 cm
  • occur in moderate PET deserts (potential evapo-transpiration)
  • Lichen cover is <40%
  • Soils freeze in winter
43
Q

Characteristics of rolling crusts

A
  • Found in cool to cold deserts
  • low PET (potential evapo-transpiration)
  • soils freeze
  • Restricted to about 5cm-7.5cm
44
Q

What is false about microbial mats and biocrust?
a) Both are composed of microbial communities.
b) Cyanobacteria play a significant role in both.
c) They exhibit similar structural formations.
d) Microbial mats primarily form in aquatic environments

A

c) They exhibit similar structural formations.

45
Q

What is the dominant organism shown in this soil surface after crust formation
What do they go?

A
  • spherical, large, multicellular, Cyanobacteria, Nostoc group
  • fix nitrogen from the atmosphere thus allowing succession of other life forms
46
Q

life cycle of heterocyst-forming cyanobacteria (Such as Nostoc): what is formed in…
* low nitrogen (deprivation)
* high nitrogen
* energy-limiting conditons

A
  • low nitrogen (deprivation) = heterocysts
  • high nitrogen = just vegetative cells
  • energy-limiting conditons = akinetes
  • can also produce Hormogonia (dispersal forms) in certain condtions

ALL interconnected

47
Q

Cyanobacteria can fix both Nitrogen and CO2 - how?

A

Cellular differentiation
* Heterocysts fix atmospheric nitrogen
* Vegetative cells fix CO2

48
Q

3 specialized cells of* Nostoc* & what they do

A
  • Akinetes: Dormant specialized cell (unfavorable conditions). germinates as new vegetative cells, allowing the organism to resume growth and reproduction.
  • Heterocyst: Nitrogen fixation
  • Hormogonia: For dispersal
    (favorable conditions for symbiosis). They are filaments of cells, and can stablish new colonies.
49
Q

When Nostac clumbs together what does it form

A

Nostac forms filaments that clump together in large balls of mucilage

50
Q

Cyanobacteria as food

A

Nostoc commune “Llullucha” or “cushuro” in Peru
* yummy but contain BMAA = neurotoxin
* Nitrogen fixers so good source of protein

51
Q

Habitat of Nostoc balls

A

inhabits high altitudes and thrives in low temps with high UV radiation
* Atacama Desert, Chile
* Oligotrophic locations with tadpoles

52
Q

Role of exopolysaccharides (EPSs) in cyanobacteria

A
  • adhesion
  • structure
  • protection against a-biotic stresses (water stress, UV stress, physical and chemical stresses)
  • bioweathering processes
  • gliding motility
  • nutrent repositories
53
Q

Which is true about Nostoc sp.:
a) Heterocysts are specialized cells for the survival of Nostoc during unfavorable conditions.
b) Scytonemin is responsible for nitrogen fixation.
c) Vegetative cells have Nitrogenase.
d) Scytonemin is a photoprotective pigment against harmful UV radiation.

A

d) Scytonemin is a photoprotective pigment against harmful UV radiation.

Microbiology (9 decks)

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