Archaea

FYBSc-Microbiology
SIWS College
Mumbai University

1. Archaea
Greek-archaiosmeans ancient

2. Introduction
•Diverse group
•Gram Positive or Gram Negative
•Spherical,lobed,rod-shaped,spiral,cubodial,
triangular,plateshaped,irregularlyshaped,
•Pleomorphic
•Presentasasinglecells,oraggregates/filaments
•Multiplication-binaryfission,fragmentationand
othermechanisms
•Physiologicallydiverse-aerobic,facultative
anaerobes,strictlyanaerobes

3. •Chemolithoautotroph,organotroph
•Psychrophiles,mesophilesandhyperthermophiles
(can grow above 100
0
c)

4. Ecology
•They live in an extreme environment
•Area with very high or low temperature, PH
•Area with high salt concentration
•Area with high concentration of methane
•Area with no oxygen (anoxic)

5. Volcanic eruptions

6. Amazing Geyser Landscape in
Nevada

7. thevivid red brine (teaming withhalophilic
archaebacteria) of Owens

8. Halophiles in sea

9. Great Salt Lake of Utah

10. methanogens may thrive in hot springs

11. ArchaealCell Wall
•Lackmuramicacid and D-amino acids
•Eg.methanogenshavepeudomurein(a
peptidoglycanlikepolymerthatiscross-linked
withL-aminoacids
•Somecontainacomplexcarbohydratesimilarto
chondroitinsulfateofanimalconnectivetissue
•Hyperthermophileandmethanogenshaveproten
cellwall

12. Archaealmembrane
•Branchedchainhydrocarbonattachedtoglycerol
byether
•Thermophilearchaeahavelongtetraetherintheir
cellmembrane.AlsopentacyclicringsinHCof
some(helpmaintainthedelicateliquidcrystalline
balanceofmembraneofmembraneathigh
temperature)
•Otherlipids-polarphospholipid,sulfolipid,
glycolipid.

13. MajorArchaealgroups
Methanogenicarchaea
Archaealsulfate reducers
Extremelyhalophilicarchaea
Cell wall-lessarchaea

14. MethanogenicArchaea
•Strictanaerobes
•Producesmethaneasamajormetabolicend
product
•Convertsulfurtohydrogensulphidewthnoenergy
production
•Theypossessco-enzymeM,factor420/430,
methanopterin
•Eg. Metanobacterim, Methanococcus,
Methanomicrobium,Methanosarcina

15. Archaealsulfate reducers
•Irregular gram-negativecoccoidcells
•Strictly anaerobe and extremelythermophilic
•Hydrogen sulfide is formed fromthiosulfateand
sulfate
•Heterotrophic in nature, autotrophic growth with
thiosulfateand hydrogen
•Forms traces of methane
•Possess factor 420 andmethanopterin
•Eg.Archeoglobus

17. Extremelyhalophilicarchaea
•Rods,cocci,irregularshaped(pyramid,cubeetc)
•Staingram-positiveandgram-negative
•Chemoorganoheterotroph
•Lackpeptidogycan
•Mostspp.requiresodiumchloride(>or=15M)
•Mostlyproducebrightredcolonies
•Someunpigmented
•Neutrophilictoalkalophilic
•Generallymesophilic,onesp.isthermophilic
•Possessbacteriorhodopsinandhalorhodopsin(
andcanuselightenergytoproduceATP

18. Cell wall-lessArchaea
•Pleomorphiccell lacking cell wall
•Thermoacidophilicandchemoorganotrophic
•Facultaiveanaerobes
•Mannose-rich glycoprotein and alipoglycan

19. Extremelythermophilicelementary sulfur
•Gram negative rods, filaments orcocci
•Obligatorythermophile(70-110
0
c)
•Usually strictly anaerobe, some are aerobic and
facultative
•Acidophilic andneutrophilic
•Autotrophic or heterotrophic
•Reduction of sulfur to hydrogen sulfide–
anaerobicallyand hydrogen sulfide or elemental
sulfur oxidized to sulfuric acid aerobically
•eg.Desulfurococcus,Sulfolobus,Thermococcus

20. Economic Importance
•Thermophilesgrowinheatedwaterandsoilrichin
elementalsulfurandtheseenvironmentarescattered
allovertheworld.Eg.Sulfurrichhotspringsin
YellowstoneNationalPark
•Methanogensproducemethaneusingsewagesludge,
whichisacleanburningfuel(pollutionfreeenergy)
•Methaneproductioncancontributetoglobalwarming
•Halophilesareusedintheproductionofmanysalted
foodproducts,includingsoysauce
•Thermoplasmaoxidizesironsulfide(inpilesofcoal
mines)tosulfuricacid.Asaresultpilesbecomehot
andacidic

21. Yellowstone National Park