Halobacteria
Published on Nov 18, 2015
No Description
MORE DECKS TO EXPLORE
PRESENTATION OUTLINE
HABITAT
- Environments with salt, moisture, and large amounts of organic material are available
- These include salt production facilities, salt mines, the Dead Sea, and the Great Salt Lake
- Require at least a 2M NaCl solution to grow
- Grow best in 4 to 5M NaCl solutions
- Live mainly in harsh environments
Photo by szeke
CELL WALL
- Surrounded by a single bilayer membrane
- That is surrounded by an S-layer made from cell-surface glycoprotein
- There's an excess amount of acidic amino acids in the proteins
- This accounts for electrostatic shielding of -charges at a low concentration
MODE OF LIVING/SHAPE
- Live in colonies
- Rod shaped
SIZE
- Genome size of 2Mb
- There is 1 chromosome and 2 plasmids
MOBILITY
- Uses flagella and gas vesicles to move
- Swim towards green light, but away from damaging UV light
- Can swim forward and backward in straight lines
- Have the ability to reorient themselves
- Use a process called chemotaxis to move towards a desired chemical
How do they obtain carbon/energy?
-Can't fix carbon from CO2
-Have 4 retinal proteins involved in light energy conversions and signal transduction
-3 ways to obtain energy
1) FERMENTATION OF ARGININE
- Halobacteria generates ATP by its Arginine fermentation pathway
2) Photosynthesis
-bacteriorhodopsin, a light-driven proton pump, creates a proton gradient
-ATP synthase uses the energy of the proton gradient to drive ATP synthesis
3) Oxidation of various metabolites
-Oxidizes pyruvate which is channeled into the tricarboxylic acid cycle
-Halobacteria contains all 5 major complexes of the respiratory chain
-obligate aerobic
A RANGE OF DIFFERENCES
- Optimal growth temp- 37-42 degrees Celsius
- Need 2M NaCl solution to grow
- Grow best in 4 to 5M NaCl solution
- Sea water has .6M NaCl
EVOLUTIONARY RELATIONSHIPS
- Halobacteria is more closely related to eubacteria than archaebacteria
- Membrane transport systems have evolved for ionic movements
- Cohesive forces are weak in their proteins, prevents aggregation in salt
- Halobacteria can only thrive in high salt concentrations
- The less oxygen in an environment, the more colorful they'll be
BIOLOGICAL IMPLICATIONS FOR CATEGORIZING
- Their habitats
- Ex) halophiles because survive in high salinity
- Genomes
Physiological implications for categorizing
-for prokaryotes, it depends on if there is peptidoglycan in their cell walls
Definition of the biological species concept
-a population whose members have the potential to interbreed in nature and produce viable, fertile offspring, however they cannot do the same with other populations
WHY DOES THIS NOT APPLY?
- Prokaryotes reproduce asexually
- They do not interbreed
