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MBIO 1010 > Prokaryotic Diversity- Bacteria > Flashcards

Prokaryotic Diversity- Bacteria Flashcards

Lectures 26-29

1
Q

What are the two ways to describe microbial diversity?

A

Phylogenetic and Functional diversity

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2
Q

How does phylogenetic diversity work?

A

Microbes are grouped into phyla based on evolutionary relationships. Most often based on 16S rRNA gene sequence.

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3
Q

Phylogenetic tree for microbial diversity what do the red dots represent?

A

Phyla only known from metagenome sequencing from diverse environmental samples.

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4
Q

What does the phylogenetic tree as of 2016 include regarding microbial diversity?

A

The tree includes 92 named bacterial phyla, 26 archaeal phyla and all five of the Eukaryotic super groups.

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5
Q

How does functional diversity work? What are two examples?

A

It groups microbes based on the activities they carry out. For example:

  1. Anoxygenic phototrophs- dispersed through several phyla
  2. Oxygenic phototrophy- one phyla
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6
Q

Which bacterial phyla includes the Mycoplasmas and are phylogenetically related to Gram positives, but they don’t have a cell wall?

A

Tenericutes

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7
Q

Define the term ‘Mycoplasmas’.

A

Any of a group of small typically parasitic bacteria that lack cell walls and sometimes cause diseases.

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8
Q

True or False: Tenericutes stain gram- even though they are phylogenetically related to gram+.

A

True

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9
Q

Tenericutes are typically pleomorphic- what does this mean?

A

Pleomorphic means a micro-organisms will alter their shape or size in response to environmental conditions.

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10
Q

When is an example of a Tenericute? What is special about it?

A

Mycoplasma genitalium- An STI that is the common cause of urethritis and pelvic inflammatory disease. It was the first free-living bacterium to have it’s genome sequenced.

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11
Q

True or False: Mycoplasma genitalium has one of the smallest genomes sequenced at 500 kbp.

A

True

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12
Q

Which bacterial phylum includes gram+ organisms including a high amount of guanine-cytosine content (GC) gram+’s?

A

Actinobacteria

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13
Q

What kind of bacteria does Actinobacteria include? What shape are they?

A

Actinobacteria include coryneform bacteria, which are club-shaped.

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14
Q

What is an example of Actinobacteria that are coryneform? What do they do?

A

Corynebacterium diphtheriae- produces an exotoxin that inhibits protein synthesis. It can cause tissue death in the respiratory tract (diphtheria) and can lead to death by suffocation.

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15
Q

Mycobacteria is another bacteria that falls under Actinobacteria. What is different about this specific bacteria?

A

It has a modified gram+ cell wall. There is a layer of mycolic acids outside the peptidoglycan layer that makes the bacteria acid-fast. Crystal violet will not stick to this bacteria.

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16
Q

What is an example of Actinobacteria that are mycobacteria? What does it cause?

A

Mycobacterium tuberculosis- a slow growing (~ 24 hr/gen) bacteria in which its colonies can take weeks to form on agar medium. It causes tuberculosis, a slow, fatal respiratory disease.

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17
Q

Which bacterial phylum includes filamentous gram+ bacteria?

A

Filamentous Actinobacteria

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18
Q

What do Filamentous Actinobacteria form?

A

Branching hyphae and mycelium.

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19
Q

What do the hyphae produce? What do they not produce?

A

The hyphae produce reproductive spores for dispersal- conidia. They do no produce endospores.

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20
Q

True or False: Most Filamentous Actinobacteria are obligate anaerobes who live in well aerated soils.

A

False: Most Filamentous Actinobacteria are obligate aerobes, but they do live in well aerated soil.

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21
Q

What gives soil that earthy smell?

A

Geosmins

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22
Q

What do most Filamentous Actinobacteria produce?

A

They produce substances that kill or inhibit the growth of other microbes antibiotics.

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23
Q

What is an example of Filamentous Actinobacteria? What does it produce?

A

Streptomyces griseus- produces streptomycin, a broad spectrum protein synthesis inhibitor active against Gram negative bacteria.

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24
Q

Which bacterial phylum is a large heterogenous phylum of gram- bacteria?

A

Bacteroidetes

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25
Q

True or False: Bacteroidetes are both aerobes and anaerobes with few unifying characteristics.

A

True

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26
Q

What is an example of a Bacteroidete? What does it do?

A

Bacteroides thetaiotaomicron- a strict anaerobe that is numerically dominant microbe in the human large intestine. It produces enzymes to degrade polysaccharides, greatly increasing the variety of plant polymers that can be digested in the human gut.

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27
Q

Which bacterial phylum includes a gram negative cell wall type that lacks peptidoglycan and is an obligate intracellular parasite?

A

Chlamydiae

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28
Q

Chlamydiae have a unique life-cycle that have two different types of cell. What are they?

A

Elementary bodies and Reticulate bodies.

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29
Q

What are Elementary bodies? What is their function?

A

Elementary bodies are small dense cells that resists drying. They allows infection of new host cells because they are so small and can sneak in.

30
Q

What are Reticulate bodies? What is their function?

A

Reticulate bodies are what come after elementary bodies in Chlamydiae life-cycle. They are larger vegetative cells that multiply inside an existing host. They are not infective.

31
Q

What is an example of Chlamydiae? What does it do?

A

Chlamydia trachomatis-

Trachoma: infection of the eye. This causes scarring and blindness.

32
Q

What bacterial phylum include budding and appendaged bacteria?

A

Planctomycetes

33
Q

What are the characteristics of Planctomycetes?

A

They lack peptidoglycan in the cell wall and use protein stalks for attachment. Some have membrane-bound compartments inside the cell.

34
Q

What is an example of a Planctomycete with a membrane-bound compartment?

A

Gemmata obscuriglobus- nuceoidis surrounded by a true unit membrane.

35
Q

Which bacterial phylum has morphological diversity, generally larger than other bacteria, meaning they are either unicellular, filamentous, or branching filamentous?

A

Cyanobacteria

36
Q

What do specialized Cyanobacteria nitrogen fixing cells often form? What is an example of a nitrogen fixing cell?

A

Specialized nitrogen fixing cells often form heterocysts to trap oxygen. An example of a nitrogen fixing cell is an anabaena.

37
Q

True or False: All Cyanobacteria carry out oxygenic photosynthesis and are heterotrophic.

A

False: While all Cyanobacteria carry out oxygenic photosynthesis, they are all autotrophic.

38
Q

Cyanobacteria do not use chloroplasts to carry out photosynthesis. What do they use, and how do they differ/have the same as chloroplasts?

A

They have a membrane called a thylakoid. Like chloroplasts they carry out photosynthesis. Unlike chloroplasts they contain Contain peptidoglycan and have a gram negative cell wall type.

39
Q

True or False: Because Cyanobacteria are widely distributed in terrestrial, freshwater, and marine habitats, and are primary produces, they have the highest nutritional requirement of any organism.

A

False: Although Cyanobacteria are widely distributed and primary produces, they have the lowest nutritional requirement of any organism.

40
Q

What is an example of a Cyanobacteria? What is special about it?

A

Prochlorococcus- one of the most abundant organisms on Earth. It accounts for ~ half of photosynthesis in the World’s oceans.

41
Q

Cyanobacteria often cause toxic blooms. What do toxic blooms cause in water bodies?

A

Toxic Blooms produce toxins that effect the nervous system, the liver, the skin, etc.

42
Q

What is an example of a toxic bloom?

A

Lake 227: Cyanobacterial bloom after addition of phosphate. Because many cyanobacteria fix N2, phosphate imbalance alone cause their blooms.

43
Q

Which bacterial phylum includes many of the most commonly encountered bacteria, and is also the most metabolically diverse?

A

Proteobacteria

44
Q

What are the metabolic pathway(s) included in Proteobacteria?

A

Chemolithotrophs- bacterium able to obtain its energy by the oxidation of inorganic compounds
Chemoorganotrophs- bacterium that obtains energy from the oxidation of reduced organic compounds
Phototrophs- bacterium obtaining energy from sunlight to synthesize organic compounds for nutrition
Facultative- can switch from one metabolic lifestyle to another

45
Q

Proteobacteria are divided into 6 classes- what are they? How well are they studied?

A

Alpha-, Beta-, Gamma-, are well studied with many important species.
Delta-, Epsilon-are smaller classes but with a broad range of phenotypes, also well studied.
Zetaproteobacteria has barely been studied with only one known species: Mariprofundus ferrooxydans.

46
Q

What do Alphaproteobacteria include?

A

Pathogens and non-pathogens.

47
Q

What is an example of an Alphaproteobacteria non-pathogen?

A

Rhizobium leguminosarum
Forms root nodules on legume plants
Symbiotic relationship
Bacterium fixes nitrogen into a bioavailable form
Plant provides nutrients and a home for the bacteria

48
Q

What is an example of an Alphaproteobacteria pathogen?

A

Rickettsia rickettsii-
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

49
Q

What are the characteristics of Betaproteobacteria?

A

Metabolically diverse, with some pathogens and non-pathogens.

50
Q

What is a non-pathogenic Betaproteobacteria?

A

Neisseria mucosa- non-pathogenic commensal of the human body: lives on mucous membranes.

51
Q

What is a pathogenic Betaproteobacteria?

A

Neisseria gonorrhoeae- pathogenic: causes gonorrhea (STI).

52
Q

True or False: Gammaproteobacteria are both metabolically and ecologically diverse, but do not grow well in a lab.

A

False: Gammaproteobacteria grow very well in a lab and have become important research models.

53
Q

There is a Gammaproteobacteria that is is Gram negative, rod shaped, a facultative aerobe, motile by means of peritrichous flagella, and ferments lactose to a mixture of acids and alcohols. This bacteria is a resident of the large intestine of warm-blooded animals and serves as an important indicator of fecal contamination. What is this bacteria’s name?

A

Escherichia coli (E. coli)

54
Q

What is another example of a Gammaproteobacteria besides E. coli?

A

Pseudomonas aeruginosa- The “coward” bacteria. It is:
Gram negative, rod shaped, motile by means of polar flagella
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

55
Q

What is a unique characteristic of Deltaproteobacteria?

A

Deltaproteobacteria contain bacteria with very strange habits.

56
Q

What is an example of Deltaproteobacteria?

A

Myxococcus xanthus-
Gliding motility
Predatory: releases exoenzymes to lyse other bacteria for nutrients
When starved the cells migrate together to forms complex multicellular fruiting bodies •
Individual cells differentiate into myxospores for dispersal

57
Q

What is a parasitic example of Deltaproteobacteria?

A

Bdellovibrio bacteriovorus-
Curved, highly motile predator of other Proteobacteria and Gram negative bacteria
Penetrates the cell wall and multiplies in the periplasm
Parasitic: uses macromolecules obtained directly from the host

58
Q

What are the characteristics of Epsilonproteobacteria? What are they famous for?

A

They are a small class famous for a few microaerophilic- spirillum shaped pathogens.

59
Q

What is an example of Epsilonproteobacteria?

A

Campylobacter jejuni-
Frequently transmitted in under-cooked chicken
One of the most common causes of food-borne illness Causes gastroenteritis and bloody diarrhea

60
Q

What is so deadly about gastroenteritis?

A

If there is enough damage, the bacteria will get into the blood.

61
Q

What bacterial phylum is one of the two phyla with gram+ bacteria and a low GC gram+ count.

A

Firmicutes

62
Q

Firmicutes includes lactic acid bacteria. What kind of metabolic bacteria are they that allows them to obtain lactic acid as an end product of fermentation?

A

Aerotolerant anaerobes

63
Q

What are two examples of lactic acid Firmicutes?

A 
Lactobacillus delbrueckii- 
Yogurt production 
Streptococcus pyogenes- 
Cause of strep throat, scarlet fever and the flesh eating disease
Incredibly deadly `
64
Q

What is an example of a non-lactic acid Firmicutes?

A

Staphylococcus aureus-
Facultative aerobe that forms characteristic grape-like clusters
Lives on skin
Halotolerant
Can be isolated using media with high NaCl (Ex: mannitol salt agar): produces acids-yellow Frequent cause of nosocomial infections

65
Q

What is the difference between Staphylococcus aureus and Staphylococcus epidermidis?

A

Staphylococcus aureus is more pathogenic, and Staphylococcus epidermidis comes up pink on a mannitol salt plate from lack of acid production.

66
Q

Firmicutes can also produce endospores. What are the two best studied genre of endospore producing Firmicutes?

A

Bacillus– aerobic endospore formers

Clostridium– strictly anaerobic endospore formers

67
Q

Where are endospore forming Firmicutes usually found? Are they pathogenic or non-pathogenic?

A

They are usually found in the soil- most are non-pathogenic, but there are a few that are pathogenic.

68
Q

What is an example of an endospore producing Firmicute found in soil?

A

Bacillus subtilis •
Important lab bacterium used as a model for:
-Gram positive cell structure and genetics
-Cell division and differentiation into endospores

69
Q

What is an example of an endospore producing Firmicute that is found in tiny anoxic pockets in the soil?

A

Clostridium botulinum
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
-When consumed causes botulism
Proper canning procedures must either:
-Reach temp above 120°C to destroy endospores
-Include enough acid or sugar to prevent germination

70
Q

What do Hyperthermophilic Bacteria suggest about bacterial common ancestory?

A

Suggests that the last universal common ancestor (LUCA) may have been a hyperthermophile.

71
Q

There are two famous species of Hyperthermophilic Bacteria- Thermus aquaticus and Deinococcus radiodurans. What is Thermus aquaticus?

A

A thermophilic chemoorganoheterotroph
Source of temperature stable enzymes: TaqDNA polymerase
Allows DNA synthesis reactions in the lab to be carried out quickly at high temperatures
An essential tool for polymerase chain reaction (PCR)

72
Q

What is the Hyperthermophilic Bacteria Deinococcus radiodurans?

A

Extremely resistant to radiation
-Highly effective DNA repair mechanisms
Forms pairs or tetrads
In response to massive DNA damage nucleoids from two cells can fuse to facilitate repair
Has a Gram negative cell wall type but stains Gram positive because of thick peptidoglycan

MBIO 1010 (14 decks)

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