Vibrio fischeri
- “Milky seas”
- Marine bacterium
- Symbiosis with squid (stores v. fischeri “light organ” and feeds bacteria which emit light)
- Luciferase enzyme (production regulated by quorum sensing)
- Produces light only at high cell density
- Quorum sensing
Advantage is to create counter-illumination (no shadow)
name hint–found in fish light organ
16S rRNA
- Nucleic acid sequence
- Found in all living things (used for comparison)
- Part of ribosomes
- Constant and highly variable regions
More similar 16S rRNA sequence = more similar bacteria
Consequences of 16S rRNA phylogeny
- 5 kingdom tree became 3 kingdom tree
- Scientists realized most biological diversity was in microscopic organisms
- Photosynthesis evolved multiple times
- Archaea were discovered
- Facilitated/changed way bacteria were named
- Enabled the field of microbial ecology
- Gave strong support for endosymbiotic theory
Epulopiscium fischelsoni
-Found in gut of surgeon fish
-Visible to the naked eye, but still a bacteria!
-VERY unusual cell division, deviation from Binary Fission
> daughter cells grow inside mother cells
> mother cell is killed when daughters are released
name hint–found in fish gut
Escherichia coli
-E. coli (K12) most studied organism EVER, helpful gut microbe (no pili)
-E. coli (O157:H7) dangerous pathogen, phage infection introduces toxin and pilus on chromosome
^ identical 16S rRNA but chromosomes only 75% similar
Phage
Viruses (proteins and nucleic acids) that infect bacteria
Lysogeny strategy (in E. coli):
- Inserts its genome into E. coli genome
- Phage genes replicated by E. coli
- E. coli now secretes Shiga toxin (damages human cells)
Shiga toxin
A/B toxin
Destroys eukaryotic ribosomes to kill host cell
Mycoplasma pneumoniae
- Causes “walking pneumonia”
- Among smallest bacteria
- Uses cholesterol to buffer membrane fluidity
- “Attachment organelle” that allows for Gliding motility
name hint–begins with “M” … think of Motility (Gliding)
Magnetospirillum magnetotactum
- Contains magnetosomes (Storage granules of magnetite)
- Uses magnetosomes to orient motility in a magnetic field
- These magnetosomes are actually membrane invaginations
- MamK filament organizes magnetosomes inside of cell
name hint–magneto for magnetosomes
Storage granules
1) Energy storage
2) Element storage
3) Damaged proteins
Mycobacterium tuberculosis
- # 1 infectious bacterial pathogen (infects the lung)
- Thick, waxy cuticle
- Unusual capsule, two EPS layers with a unique waxy, mycolic acid lipid layer between them
- Resistant to most everything, but grows VERY slowly
Extracellular polysaccharides (EPS)
Extra, non-essential, layers beyond the peptidoglycan
ex: Capsule, Slime layer
Caulobacter crescentus
-Asymmetric division (swimmer cell, stalked cell)
^ stalked cell produces multiple swimmers
-Grows in very dilute water
-World’s strongest glue “holdfast”
name hint–think of a crescent as asymmetrical
Deinococcus radiodurans
-Isolated from an irradiated can of meat
-Extremely radiation resistant
-Nucleoid is compacted into a “torus”
^ contains many copies of the chromosome to be able to quickly reassemble after radiation damage
name hint–radiodurans, relate to radiation
Radiation
Ionizes most common molecule in the cell (water), which then attacks the largest molecule in the cell
Bdellovibrio bacteriovorus
- Intracellular predator of Gram Negative bacteria
- Pulls itself into the periplasm with Type IV pili
1) Infects periplasm
2) Elongates and solidifies host outer membrane
3) Does not use binary fission, multiple simultaneous divisions
4) Host lysis and release
name hint–bacteriovor, think of preying on bacteria
Chlamydia trachomatis
- Causes most common STD in the United States
- Intracellular pathogen, grows inside human cells
- Lacks FtsZ
- Cannot make own ATP, steals energy from host
Alternates between two cell types, “elementary body” (EB) or dormant form and “reticulate body” (RB) or growing form
Cloistridium acetylbutylicum
- Gram positive, soil bacterium
- Can eat unusual substrates, dynamite (TNT)
- Ferments sugars to acetone (gunpowder) and butanol (rubber/biofuel)
- Possible biofuel source
name hint–creates acetone (acetyl) and butanol (butyl)
Fermentation
Strategy to burn excess NADH and restore the pool of NAD+, electrons dumped back onto the substrate
Geobacter metallireducens
- Gram negative, soil bacteria
- Consumes sugars, respires metals
- Pili conduct electrons outside cell “nanowires”
Nanowire
- allows respiration of insoluble metals
- conductive pilis anchored in plasma membrane and part of the electron transport chain
name hint–think of “metallireducens” … respire metals
Respiration
Use of an electron transport chain to make proton motive force
Halobacterium salinarum
-Archaea
-Extremely halophilic, desiccation/radiation resistant
-Bacteriorhodopsin phototrophy
^ single proton pump directly coupled to light absorption (does not use Electron Transport Chain)
-requires photo-pigment cofactor, found in the human eye
name hint–halo- prefix (like salt)
Sinorhizobium meliloti
- Soil bacterium, legume symbiont
- Fixes nitrogen in plant nodules
- Form symbioses with different bacteria
- Plant gets nitrogen–bacterium gets carbon
- Receives/sends signals to plant, infects through infection thread, forms bacteriods, make rhizopines (energy source) to feed bacterium on outside of plant
- leghemoglobin–similar to hemoglobin, safely delivers bound oxygen to bacteroid. Controls oxygen so as not to destroy nitrogenase
name hint–“rhizo” for rhizopines (energy source) to feed bacterium on outside of plant
Rhizopines
An exotic carbon, nitrogen, and energy source that only the Sinorhizobium on the outside can eat
