Discussion of major archaeal taxa and the two domain tree of life

1. The Microbial Zoo 4
A stroll through the microbial world
Rachel Mackelprang, Ph.D.
California State University Northridge
Department of Biology
rachel.mackelprang@csun.edu
@rmackelprang
Book: Principles of Microbial Diversity by James Brown
Section II

2. Archaea: the traditional view

3. Crenarcheota
Though often characterized as acid-lovers, they are more diverse
than that
• Most are thermophilic and
acidophilic (though some are
alkaliphiles
• Sulfolobus lives in hot sulfur
springs (70-75C, pH 2-3)
• But maintain an internal pH
of near 7

4. Crenarcheota
Some exceptions: alkaliphilic crenarcheota
New alkalithermophilic
crenarcheota have been found
here

5. Crenarcheota
Some exceptions: alkaliphilic crenarcheota
New alkalithermophilic
crenarcheota have been found
here
Geothermic energy
company drilled a well but
water was not hot
enough. Capped well, but
seal failed. Dissolved
mineral in water created
formation

6. Euryarchaeota

7. Euryarchaeota: methanogens
• Many Euryarchaeota are
methanogens: produce
methane (CH4) by reducing
CO2 (obligate anaerobes)
• Methanogens release 2 billion
too of methane per year
• Many live in the guts of
grazing mammals
• Increased cattle farming, rice
farming, and permafrost thaw
release methane into the
atmosphere

8. Euryarchaeota: Halophiles
• Red pigments make it obvious when
large numbers are present
• Red Sea gets name from blooms
• Up to pH of 11.5
• Live in the most salty most alkaline
environments on Earth
• May contribute to the pink color of
flamingoes

9. Traditional three-domain tree may be incorrect

10. Traditional three-domain tree may be incorrect

11. Traditional three-domain tree may be incorrect

12. Evidence for new view is rapidly emerging

13. How you build the tree is important

14. Taxon sampling

15. Taxon sampling
13

16. Another view