Lecture #7 - Prokaryotic Diversity PART II ARCHAEAL DIVERSITY Flashcards
Diversity of Archaea
- Phylogenetically Archaea are split into FIVE phyla
- Breadth of phylogenetic diversity is similar to that of the Bacteria and Eukarya
- even though there’s a small # of phyla here, each of them will be “RICH” with diversity
- comparable to bact that might have a phylo tree that’s more extensive, the diversity b/t the 2 are comparable
- lot of unique organisms that can do a lot of metabolism & activities
Phylogenetically Archaea are split into FIVE phyla…
- Euryarchaeota
- Nanoarchaeota
- Korarchaeota
- Crenarchaeota
- Thaumarchaeota
Euryarchaeota: Extreme Halophiles
& example
organisms like excessively high salt levels
- Haloarchaea
- Also known as halobacteria (still an archaean)
• Example: Halobacterium salinarum
• ABSOLUTE requirement for high salt concentrations
- a must!
• Typically need at least 1.5 M (~9%) NaCl for growth
- remember: cytoplasm & normal ECF is normally gonna be ~0.9% NaCl
- this is ~10x higher than a normal isotonic condition
- water wants to rush out normally, but this organism can’t have that so will maintain its water
• Found in solar salt evaporation ponds and salt lakes where the salt concentration approaches saturation
• Ex) Great Salt Lake (Utah), Dead Sea
• Ex) soda lakes (highly alkaline hypersaline lakes)
- lot of NaCl & high pH b/c of alkalinity
Euryarchaeota: Extreme Halophiles
Adaptations for highly ionic environments
•Halophiles need to maintain osmotic balance
- b/c these organisms are gonna want to lost their water due to highly hypotonic EC conditions
• Usually achieved by accumulation or synthesis of COMPATIBLE SOLUTES
- will offset the outward movement of water
Halobacterium salinarum pumps large amounts of K+ INTO the cell from the environment
• Intracellular K+ concentration EXCEEDS extracellular Na+ concentration
- but now have really high K+ (normally in cell anyway), allows…
• WATER flows INTO the cell in hypersaline environments
- maintain balance
- even though outside says come, inside says not
- allows cell to keep all cytoplasmic conditions that the cell needs for growth & survival, despite the fact that there’s a gong show outside the cell (extremely salty EC [ ])
Euryarchaeota: Extreme Halophiles
Some haloarchaea have a unique system for
generating energy:
- Light-driven synthesis of ATP WITHOUT the use of chlorophylls
- Instead they use a pigment called BACTERIORHODOPSIN
Euryarchaeota: Extreme Halophiles
Bacteriorhodopsin
- uses light energy to generate a PMF
- no chlorophyll
• INTEGRAL membrane protein
• ABSORBS LIGHT energy and pumps protons across the membrane to MAKE a PMF
- from low –> high [ ]
• PMF is used to generate ATP
• They do NOT fix CO2
• Ex) Photoheterotrophy **underrepresented group!
- b/c light energy is being used & you’re not using fixing CO2 b/c not autotrophic
Euryarchaeota: Extreme Halophiles
Bacteriorhodopsin
Is similar to chloroplast in cyanobacteria BUT…
here you don’t fix CO2 & doesn’t happen from e- transfers & energy release (happens from light energy)
Euryarchaeota: Methanogenic Archaea
• Only microbes capable of significant methane production: Methanogens
• Ex) Methanobacterium (remember: an archaean)
4H2(energy) +CO2 (e- acceptor) –> CH4 (end product) +2H2O
- Produce the bulk of CH4 in the atmosphere
- Important green house gas (that traps a high amount of heat)
• STRICT ANAEROBES, found in many diverse anaerobic environments
- not using O2 b/c can’t tolerate it
• Ex) Cow’s gut; Sewage sludge
- large intestine is anaerobic
- has methanogens within that produce CH4 gas that escapes to atm & creates warming effect
What energy category would we put Euryarchaeota: Methanogenic Archaea
CHEMOLITHOTROPH - b/c using inorganic forms of energy
Euryarchaeota: Methanogenic Archaea
Demonstrate diversity of cell wall chemistries
- have archaeal cell types
• Pseudomurein used in Methanobacterium
• Similar in structure to peptidoglycan
*- REPEATING DISACCHARIDE
• Less similar in composition to peptidoglycan
*-NO NAM (but is replaced by n-acidicneuronic acid)
• ONLY the Methanobacteriales family has this type of cell wall
• MOST OTHER types of methanogens have a S-layer made of protein or glycoprotein (protein material has sugar groups attached) (rather than carbs) as their cell wall
- therefore, A LOT OF DIVERSITY
Thaumarchaeota
Accomplishes nitrification
Ex) Nitrosopumilus maritimus
Thaumarchaeota
Accomplishes nitrification
ex: Nitrosopumilus maritimus
- AEROBIC, ammonia oxidizing CHEMOLITHOAUTOTROPH:
- Converts NH3 into NO2- for energy(oxidation)
- Uses CO2 for carbon
- Abundant in OPEN OCEAN WATER where they seem to be a major player in NITROGEN CYCLING
Thaumarchaeota
Ex) Nitrosopumilus maritimus
What does the NO2- its producing used for?
- its metabolic waste
- as it gets released to outside of cell it will be used for an alternative - 2nd best to O2 (O2 in aerobic envir’s. is a terminal e- acceptor)
- organisms can take it in places where O2 isn’t avail & can be used for anaerobic respir.
- opp. to do respir, using ETC in absence of avail O2
Nanoarchaeota
& example
Ex) Nanoarchaeum equitans
• One of the smallest cellular organisms (~0.4 μm)
- which allows it to be parasitic
- OBLIGATE PARASITE of the crenarchaeote Ignicoccus
- Contains one of the SMALLEST GENOMES known
- LACKS GENES for all BUT CORE molecular processes
- DEPENS UPON HOST for most of its cellular needs
- b/c bigger you are, more (-) effect on host cell, more destructive you are gonna be, less successful you’ll be, so imp. to minimize destruction but still benefit yourself (small genome is excellent, but depends on host)
- b/c becomes much less self-sufficient when it rips these pages out of the binder (packs light –> smaller)
Korarchaeota
& example
• Ex: Korarchaeum cryptofilum
• OBLIGATELY ANAEROBIC CHEMOORGANOTROPH
- obligation to be without O2
- HYPERthermophile
- Cells are LONG, THIN filaments
• LACKS many core genes
- like nanoachaeum equitans
BUT
• Depends on other members of hot springs community and cannot yet be grown in pure culture
- b/c they’re ripped out a lot of these genes, the only option for success is to find an envir. where they could live with other community members that’ll provide them with vital info & vital material
- as a result, can’t grow in pure culture b/c they’re community members aren’t there so there’s no 1 to provide for them that they need that we don’t know exist (issue with enumerating them in lab - see this in bact & arch.)
Crenarchaeota
- Most are hyperthermophiles
- Found in EXTREMELY HOT environments:
- Boiling hot springs, deep ocean vents
• Other representatives are found in EXTREMELY COLD environments
- don’t normally get organisms that can handle BOTH environmental extremes
- therefore, proteins need to be v. stable to handle conditions
- Chemoorganotrophs or chemolithotrophs
- Most USE SULFUR in their metabolism (regardless)
Crenarchaeota
Ex: Sulfolobus acidocaldarius
- Grows IN SULFUR-RICH ACIDIC HOT SPRINGS (~90°C, pH 2)
- HYPERTHERMOPHILE and ACIDOPHILE
• AEROBIC CHEMOLITHOTROPH that oxidizes reduced sulfur or iron
• Example:
2S0 + 3O2 + 2H2O –> 2 H2SO4.
- oxidizes the elemental sulfur to form SO4
- as you go through catabolic process it releases energy that can be used for the cell (their metabolism/energy generation)
- elemental sulfur is oxidated to H2SO4 (STRONG ACID - will decrease pH - organism will tolerate that pH or die & that ORGANISM WILL TOLERATE (handle it & live)
- energy gets released - that can be used for the cell!
Asgard Superphylum of Archaea
• ONLY KNOWN from sequence analyses FROM METAGENOMES. Ecological functions unknown
- allowed us to identify the organism exists
• Metabolism inferred from sequencing
- • On the basis of sequence similarity may represent the “MISSING LINK” between Archaea and Eukarya (more closely related than archaea & bact)
- thought to be a potential evolutionary pathway where the 2 came together & then moved forward as 1
- Euk-Asgard common ancestor - provided Euk cell structure
- Euk-alphaproteobacterium common ancestor - Rickettsia would’ve been the cell that got trapped inside that then dev. over time to be the mitochondrian
- • Members of this superphylum contain versions of genes previously thought to have been EUKARYOTE-SPECIFIC
- used the seq. to predict its metabolism
- think: someone who knows nothing about you looks through recipe book & in the book theirs no meat dishes, so person seems to think its a vegetarian
- point is: by looking at the genetic material, you can compare it to sequences known by other organisms & say you think its using this type of N-metabolism, S-metabolism for ex based on what its showing
• This group is broken down into Phyla named after the Norse gods: Lokiarchaeota, Odinarchaeota, Thorarchaeota etc.
- don’t grow it
- understand it’s there
- infer lot of info
- & maybe it’s providing a missing piece of puzzle that doesn’t have any specifics to pin down what specifically happened or who was the ancestral cell
Eukyarchaeota: Extreme Halophiles
EXAMPLE:
Halobacterium salinarum
Euryarchaeota: Methanogenic Archaea
EXAMPLE:
Methanobacterium
Thaumarchaeota
EXAMPLE:
Nitrosopumilus maritimus
Nanoacrchaeota
EXAMPLE:
Nanoarchaeum equitans
Korarchaeota
EXAMPLE:
Korarchaeum cryptofilum
Crenarchaeota
EXAMPLE:
Sulfolobus acidocaldarius
