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Microbiology > Booklet 4: Microbial Diversity > Flashcards

Booklet 4: Microbial Diversity Flashcards

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Biology 101 flashcards
1
Q

List the 2 ways to describe microbial diversity

A
  • Phylogenetic diversity

- Functional diversity

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2
Q

Describe phylogenetic diversity

A
  • Microbes are grouped into phyla based on evolutionary relationships
  • Most often based on 16S rRNA gene sequence
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3
Q

Describe functional diversity

A

Groups microbes based on the activities they carry out.

Example: an oxygenic phototrophs

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4
Q

List 6 points about cyanobacteria

A
  • Impressive morphological diversity, generally larger than other bacteria: unicellular, filamentous, or branching filaments.
  • Some form heterocysts (specialized nitrogen fixing cells)
  • All cyanobacteria carry out oxygenic photosynthesis
  • All are autotrophs (fix CO2 to build cell material
  • Carry out photosynthesis in specialized membranes called thylakoids
  • Unlike chloroplasts, they have cell walls which contain peptidoglycan and a have a gram negative cell wall type.
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5
Q

Where are cyanobacteria widely distributed?

A

In terrestrial, freshwater, and marine habitats

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6
Q

T or F: Cyanobacteria have the highest nutritional requirements of any organisms

A

False - they have the lowest nutritional requirements of any organism. They are known as primary producers.

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7
Q

What is an example of a cyanobacteria?

A

Prochlorococcus

  • One of the most abundant organisms on earth
  • Accounts for half of photosynthesis in the world’s oceans.
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8
Q

Describe Proteobacteria

A
  • Includes many of the most commonly encountered bacteria
  • Most metabolically diverse phylum
    • chemolithotrophs
    • chemoorganotrophs
    • phototrophs
    • facultative organisms that can switch from one metabolic lifestyle to another
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9
Q

Proteobacteria are divided into 6 classes. What are they?

A
  • Alpha - well studied
  • Beta - well studied
  • Gamma - well studied
  • Delta - mostly known for strange bacteria
  • Epsilon - mostly known for strange bacteria
  • Zetaproteobacteria - has barely been studied with only one known species
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10
Q

What does alphaproteobacteria include?

A

Pathogens and non-pathogens

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11
Q

What is an example of a non-pathogen within alphaproteobacteria?

A

Rhizobium leguminosarum:

-forms root nodules on legume plants which is a symbiotic relationship

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12
Q

Describe a symbiotic relationship

A
  • bacterium fixes nitrogen into a bioavailable form

- plant provides nutrients and home for the bacteria

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13
Q

What is an example of a pathogen within alphaproteobacteria?

A

Rickettsia rickettsi:

  • Obligate intracellular pathogen
  • Carried by insects and transmitted by insect bites
  • Causes Rocky Mountain spotted fever
  • Phylogenetically, Rickettsia is the closest relative to the eukaryotic mitochondrion
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14
Q

What does facultative mean?

A

It can switch from one form of metabolism to another (anaerobic or aerobic) in order to survive.

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15
Q

T or F: Betaprotobacteria have both non-pathogens and pathogens.

A

True - they are quite metabolically diverse

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16
Q

What is an example of betaprotobacteria?

A

Neisseria mucosa:
-it is a non-pathogenic commensal of the human body and it lives on mucous membranes
Neisseria gonorrhoea:
-pathogenic - causes the STI of gonorrhoea

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17
Q

What is an example of gammaproteobacteria? Describe it.

A

E. coli:

  • gram negative, rod shaped, facultative aerobe, motile by means of peritrichous flagella
  • ferments lactose to a mixture of acids and alcohols
  • resident of the large intestine of warm-blooded animals
  • serves as an important indicator of fecal contamination
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18
Q

What is another example of gammaproteobacteria? Describe it.

A

Pseudomonas aeruginosa:

  • gram negative, rod shaped, motile by means of polar flagella, but does not ferment sugars
  • naturally resistant to many antibiotics and disinfectants
  • opportunistic pathogen (causes infections in immunocompromised patients - ex: respiratory tract infections in cystic fibrosis patients)
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19
Q

What is an example of deltaproteobacteria? Describe it.

A

Myxococccus xanthus:

  • gliding motility
  • predatory - releases exoenzymes to lyse other bacteria for nutrients
  • when starved these cells migrate together to form complex multicellular fruiting bodies
  • individual cells differentiate into myxospores for dispersal
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20
Q

Describe firmicutes

A
  • one of two phyla with gram positive cell walls
  • low GC (low guanine and cytosine - means it’s less temperature stable)
  • gram positives
  • includes lactic acid bacteria - fermentation produces lactic acid as an end product
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21
Q

List and describe 3 examples of firmicutes

A
  1. Lactobacillus delbreuckii:
    - involved in yogurt production
  2. Streptococcus pyogenes
    - cause strep through, scarlet fever and the flesh eating disease
  3. Staphylococcus aureus
    - facultative aerobe that forms characteristic grape-like clusters
    - lives on skin
    - halotolerant - can be isolated using media with high NaCl like a mannitol salt agar
    - frequent cause of nosocomial (hospital) infections
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22
Q

What are the two best studied genera of endospore formers?

A
  • Bacillus - aerobic endospore formers

- Clostridium - strictly anaerobic endospore formers

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23
Q

Where are endospores primarily found?

A

In the soil

24
Q

T or F: Most endospore forming firmicutes are pathogenic saprophytic soil organisms.

A

False - most on non-pathogenic however some can be dangerous pathogens

25
Q

Describe Bacillus subtilis (an endospore forming firmicute)

A

Important lab bacterium used as a model for:

  • gram positive cell structure and genetics
  • cell division and differentiation (into endospores)
26
Q

Describe Clostridium botulinum (an endospore forming firmicute)

A
  • strict anaerobe with a fermentative metabolism
  • lives in tiny anoxic pockets in the soil
  • secretes a variety of exoenzymes to degrade plant material
  • can also grow in anaerobic canned foods
  • produces a deadly neurotoxin which wen consumed causes botulism
27
Q

What do proper canning procedures to prevent getting botulism include?

A
  • Reach temp above 120 degrees C

- Or, include enough acid or sugar to prevent germination

28
Q

What are Tenericutes: the Mycoplasmas?

What is an example? Describe it.

A

-Phylogenetically related to gram positives but they don’t have a cell wall so they stain gram negative
-Often pleomorphic
Example: Mycoplasma genitalium
-common cause of urethritis and pelvic inflammatory disease
-first free-living bacterium to have it’s genome sequenced
-one of the smallest genomes known at 500 kbp

29
Q

What are Actinobacteria?

A
  • second phylum of gram positive bacteria
  • high GC (high guanine and cytosine - means it’s more temperature stable)
  • gram positive
30
Q

Provide and describe an example of an Actinobacterium?

A

Corynebacterium diphtheriae:

  • club shaped morphology
  • produces an exotoxin that inhibits protein synthesis
  • causes tissue death in the respiratory tract (diphtheria)
  • can lead to death by suffocation
31
Q

Mycobacteria are also a division of Actinobacteria. Describe them.

A

-Mycobacteria have a modified gram positive cell wall
-Layer of mycelia acids outside the peptidoglycan layer which makes them acid fast
Ex: Mycobacterium tuberculosis
-slow growing
-colonies can take weeks to form on agar medium
-cause of tuberculosis which is a slow fatal respiratory disease

32
Q

Streptomycin are a type of filamentous Acintobactera. Describe them.

A

-genus of filamentous gram positives
-form branching hyphae and mycelia
-hyphae produce reproductive spores for dispersal known as CONIDIA
NOTE: conidia are not endospores!!
-most are obligate aerobes
-live in well aerated soils
-also produce substances that kill of inhibit the growth of other microbes (antibiotics)

33
Q

What gives soil it’s earthy smell?

A

Geosmins

34
Q

What are bacteroidetes? Provide an example

A

-large, heterogenous phylum of gram negative bacteria
-aerobes and anaerobes
-few unifying characteristics
Example: Bacteroides thetaiotaomicron
-strict anaerobe
-numerically dominant microbe in the human large intestine
-produces enzymes to degrade polysaccharides, greatly increasing the variety of plan polymers that can be digested in the human gut

35
Q

What are chlamydiae?

A
  • gram negative cell wall type, but lack peptidoglycan
  • obligate intracellular parasites
  • unique life-cycle with two types of cells: elementary body and reticulate body
36
Q

Describe the elementary body of chlamydiae.

A
  • small dense cell, resists drying

- allows infection of new host cells

37
Q

Describe the reticulate body of chlamydiae.

A
  • larger vegetative cells

- multiply inside an existing host but are not infective

38
Q

What is an example of chlamydiae?

A

Trachoma (infection of the eye)

-causes scarring and blindness

39
Q

Describe planctomycetes

A
  • budding and appendages bacteria
  • protein “stalk” used for attachment
  • lack peptidoglycan in the cell wall
  • some have membrane-bound compartments inside the cell
40
Q

What is an example of a plantomycete?

A

Gemmata obscuriglobus:

-nucleoid is surrounded by a true-unit membrane

41
Q

What suggests that the last universal common ancestor (LUCA) may have been a hyperthermophile?

A

There are several deeply branching phyla that consist of hyperthermophilic bacteria

42
Q

What are the two famous specious of hyper thermophilic bacteria?

A
  • Thermus aquaticus

- Deinococcus radiodurans

43
Q

List 4 points about Thermus aquaticus

A
  • A thermophilic chemoorganohereotroph
  • Source of temperature stable enzymes - Taq DNA polymerase
  • Allows DNA synthesis reactions in the lab to be carried out quickly at high temperatures
  • An essential tool for PCR (polymerase chain reaction)
44
Q

List 4 points about deinococcus radiodurans

A
  • Extremely resistant to radiation
  • Highly effective DNA repair mechanisms
  • Forms paris or tetrads. In response to massive DNA damage, can fuse nucleotides from two cells to facilitate repair
  • Has a gram negative cell wall type, but stains gram positive because of thick peptidoglycan
45
Q

Phylogenetically, how many phyla are Archaea slit into? List them.

A

Five:

  • Euryarchaeota
  • Nanoarchaeota
  • Korarchaeota
  • Crenarchaeota
  • Thaumarchaeota
46
Q

Euryarchaeota are extremely halophilic Archaea. They are known as Haloarchaea. Describe their nutritional requirements and where they can be found.

A

Key genus: Halobacterium

  • Have a requirement for high salt concentrations
  • Typically require at least 1.5 M (9%) NaCl for growth
  • Found in solar salt evaporation ponds, and salt lakes where the salt concentration approaches saturation
  • Also found in Great Salt Lake (Utah), Dead Sea, as well as Soda Lakes that are highly alkaline hyper saline environments
47
Q

Describe the water balance of halophilic archaea.

A
  • Halophiles need to maintain osmotic balance
  • This is usually achieved by accumulation or synthesis of compatible solutes
  • Halobacterium species instead pump large amounts of K+ into the cell from the environment.
  • Intracellular K+ concentration exceeds extracellular Na+ concentration and positive water balance is maintained
48
Q

What is a unique feature found in only some haloarchaea? Describe it.

A
  • Light-driven synthesis of ATP using bacteriorhodopsin (the reason cells are pink).
  • Cytoplasmic membrane proteins that can absorb light energy and pump protons across the membrane to make ATP
  • Cannot fix CO2
  • Therefore, they are photoheterotrophs!
49
Q

What are the 2 key generas of Euryarchaeota: Methanogenic Archaea? Describe them.

A

-Methanobacterium
-Methanosarcina
They are termed Methanogens because they are the only microbes capable of significant methane production.
They produce the bulk of CH4 in the atmosphere.
They are strict anaerobes. Ex: cow’s gut, sewage sludge

50
Q

What is pseudomurein?

A
  • A similar structure to peptidoglycan
  • Only the Methanobacteriales family has this type of cell wall
  • Most other types of methanogens have a S-layer made of protein or glycoprotein as their cell wall.
51
Q

What are examples of substrates that obligate aerobes use?

A

H2 + CO2, formate, acetate, methanol

52
Q

What is the key genus of Thaumarchaeota?

List some points about it.

A

Nitrosopumilus :

  • grows chemolithotrophically by aerobically oxidizing ammonia
  • uses CO2 as it’s only carbon source
  • can grow at very low levels of ammonia
  • indigenous to open ocean water where they are a major player in ammonia oxidation
53
Q

What is an example of Nanoarchaeota?

A

Nanoarchaeum equitans:

-Obligate symbiont of the crenarchaeote Ignicoccus

54
Q

What is an example of Korarchaeota?

A

Korarchaeum cryptofilum:

  • obligately anaerobic chemoorganotroph
  • hyperthermophile
  • cells are long, thin filaments
55
Q

Describe Crenarhaeota

A
  • Most are hyperthermophiles (Found in extreme heat environments)
  • Other representatives are found in extreme cold environments
  • Chemoorganotrophs or chemolithotrophs
56
Q

What is an example of Crenarchaeota?

A

Sulfolobus:

  • grows in sulphur-rich acidic hot springs
  • aerobic chemolithotrophs that oxidize reduced sulphur or iron

Microbiology (8 decks)

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