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Flashcards in Gram Negative Bacteria Deck (21)
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1
Q

What five types of Proteobacteria did we go over in lecture?

A
  • Pseudomonads
  • Enteric Bacteria
  • Vibrio
  • Spirelia
  • Gliding Myxobacteria
2
Q

Give a brief description of characteristics that apply to all of the microorganisms belonging to Pseudomonas and the Pseudomonads.

A
  • straight or curved rods with polar flagella
  • chemoorganotrophs
  • obligate aerobes
  • nutritionally versatile
  • ecologically important organisms in water and soil
  • some species are pathogenic
  • includes human opportunistic pathogens and plant pathogens
3
Q

Give an example of pathogenic pseudomonas.

L> animal and plant

A
  • Pseudomonas aeruginosa
    L> infections of urinary and respiratory tract
    L> infections of burn wounds
    L> lung infections in people suffering with cystic fibrosis
    L> resistant to antibodies ( R Plasmids)
    -Other pseudomonas species:
    L> plant pathogens
    L> yellow lesions of dead tissue
    L> hypersensitivity response in tobacco (prevents further spread of infection)
4
Q

Explain bioremediation wtr Pseudomonas

A
  • they are capable of breaking down many compounds to non toxic compounds
  • includes those that are not naturally occurring.
  • pesticides, dyes, heavy metals and oil
5
Q

Give a brief description of the characteristics of Enteric Bacteria.

A
  • relatively homogenous phylogenetic group including E. coli
  • facultative aerobes: respiration, ferments sugars producing a mixture of acids, H2 and CO2
  • may be motile
  • Nonsporulating rods
  • possess relatively simple nutritional requirements
6
Q

Enteric Bacteria:

  • E. coli?
  • Salmonella and Shigella?
A
  • universal inhabitants of intestinal tract of humans and warm blooded animals
    L> may synthesize vitamins for host
    L> some strains are pathogenic such as O157:H7
  • Closely related to Escherichia and is usually pathogenic
7
Q

Enteric Bacteria:

- what are the different pathotypes?

A
  • brain
  • bloodstream
  • large bowl
  • kidney
  • small bowel
  • bladder
8
Q

Vibrio Bacteria:
- describe their basic characteristics.
L> example of a well known human pathogen (Think of dirty London)

A
  • cells are motile, straight or curved rods
  • facultative aerobes/fermentative metabolism
  • most inhabit aquatic environments (fresh water or marine)
  • Vibrio cholerae causes cholera in humans
  • some are capable of light production: bioluminescence, caralyzed by luciferase, regulation is mediated by population density (quorum sensing).
9
Q

Vibrio Bacteria:

- Describe a species that is bioluminescent.

A
  • Vibrio fischeri
  • emits light
  • associated with fish (light organ develops when colonized by bacteria..Flashlight fish)
  • symbiotic relationship: host provides nutrients and shelter, luminescence can be used for communication and to hide the host from predators below.
    ex2: Bobtail squid
10
Q

Vibrio Bacteria:

- describe the biochemistry behind bioluminescence.

A

-requires enzyme luciferase, long chain aliphatic aldehyde (dodecanal (RCHO)), flavin mononucleotide (FMN) and oxygen

FMNH2 + O2 + RCHO –Luciferase–> FMN + RCOOH + H2O +Light

11
Q

Vibrio Bacteria:

- Describe Quorum sensing

A
  • in low bacterial numbers there is a low concentration of auto inducer and expression of specific genes is down regulated
  • in dense bacterial populations there is a high concentration of auto inducer and expression of specific genes is up regulated
12
Q

Vibrio Bacteria:

- Explain the regulation of bioluminescence via quorum sensing.

A
  • luciferase only expressed when cells are at HIGH DENSITY
  • this is achieved in a light organ
  • Bacteria produce an autoinducer (homoserine lactone) -> diffuses out of the cell
  • In sea water: Bacterial population density is low, HSL concentration is low, LuxR represses expression of LuxI, No HSL produced, no luciferase produced
  • In the light organ: Bacterial population density is high, HSL accumulates in cytoplasm, Lux operon activated, Luciferase produced, more HSL is produced amplifying the signal
13
Q

What are the morphologically unusual proteobacteria?

A
  • Spirilla
    L> Bdevellovibrio
    L> Campylobacter and Helicobacter
14
Q

Spirilla: Bdevellovibrio

L> Describe them.

A
  • prey on other bacteria
  • small size
  • small genome
  • highly motile
  • obligate aerobes
  • widespread in soil and water, including marine environments
15
Q

Spirilla: Bdellevibrio

L> Describe the lifecycle of Bdellevibrio bacteriovorus

A
  • attachment and penetration OM of host
    L> resides in periplasm, breaks down peptidoglycan, assimilates organic compounds from the prey cytoplasm
  • Bdellevibrio elongates without dividing
  • cell division occurs once nutrients are used up: filament divides, differentiation into motile forms, Bdellevibrio released.
16
Q

Spirilla: Campylobacter and Helicobacter

L> describe them briefly (Shared characteristics and pathogenisis)

A
  • motile
  • microaerophilic: require O2 at lower than atmospheric concentrations (3-15%)
  • most species are pathogenic to animals or humans
  • Campylobacter: enteritis (bloody diarrhoea)
  • Helicobacter: causes gastritis and peptic ulcers, can survive the acidic conditions of the stomach.
17
Q

Gliding Myxobacteria:

  • briefly describe gliding bacteria
  • briefly describe myxobacteria
A
  • typically either long rods or filaments, lack flagella but can move when in contact with surfaces
  • Gliding bacteria, form multicellular structures (fruiting bodies), complex developmental life cycles, chemoorganotrophic soil bacteria, lifestyle includes consumption of dead organic matter or other bacterial cells.
18
Q

Give an overview of gliding myxobacteria vegetative cells and myxospores.

A
  • veg: simple, nonflagellated rods, lysis of other bacteria, use released nutrients
  • Myxospores: nutrients depleted, vegetative cells aggregate, construct fruiting bodies, differentiate into myxospores, resistant to drying UV and Heat (less resistant than endospores)
19
Q

Describe the lifecycle of Myxococcus xanthus.

Gliding Myxobacteria

A
  • vegetative cycle –> swarming and aggregation -> mound of cells –myxospore and fruiting body formation–>Fruiting Body—> myxospores—>germination—>outgrowth—> vegetative cycle
  • *vegetative cells can be chemically induced to become myxospores.
20
Q

Explain gliding motility in Gliding Myxobaceria.

A
  • they have evolved several cell wall protein complexes (polysaccharides)
  • proton-motive force and hydrolysis of ATP to drive motion
  • cell movement drives rotation. Motors maintain fixed positions with respect to the substratum and push the cell body forward.
21
Q

Give a brief overview of the phylogeny of Proteobacteria.

A
  • major lineage (phyla) of bacteria
  • includes many of the most commonly encountered bacteria
  • most metabolically diverse bacteria
    L> chemolithotrophy, chemoorganotrophy, phototrophy etc
  • morphologically diverse
  • divided into five classes: Alpha-, Beta-, Delta-, Gamma- and Epsilon-