1. ARCHAEA Dr. G. M. Mohiuddin MD Resident Phase-A, Year-2
Dept. of Microbiology & Immunology, BSMMU

2. Introduction Greek αρχαία means “Old ones”.
In the past they had been classed with Bacteria as Prokaryotes (or Kingdom Monera) and named Archaebacteria.
In 1977, Woese and Fox proposed the Archaea as a third domain of life based on ssrRNA sequence cataloguing.
Present as single cell or in Aggregated or filaments.

4. Present in extreme environments (Extremophiles)
Area with High or low temperature.
Area with high salt concentration
Area with high Methane concentration
Area with no oxygen

5. Morphology Present as single cell or in Aggregated or filaments. Size:
Length: 1 to 200 micrometer
Diameter: 0.1 to 15 micrometer
Shape:
Coccus, Bacillus, Spirillium, Plate like & Pleumorphic.

8. Fig: Bacterial cell wall

9. Fig: Archaeal cell wall

11. Traits Bacteria Archaea Eukaryota
Cell Type
Prokaryotic
Eukaryotic
Cell wall Peptidoglycan
Present
Absent
Membrane lipid
Straight Carbon chains attached to Glycerol by Ester linkage
Branched Carbon chains attached to Glycerol by Ether linkage
Membrane bound organelle
Plasmid
Ribosome
70S
80S
rRNA Loop
First Amino acid in protein synthesis
Formylmethionine
Methionine
Antibiotic Sensitivity
Sensitive
Resistance
Membrane enclosed Nucleus
DNA Histone
Cell Division
Binary division
Mitosis or miosis

12. Major Archaeal Groups Thermophilic Archaea Halophilic Archaea
Methanogenic Archaea
Archaeal Sulphate Reducers
Cell wall less Archaea

13. Thermophilic Archaea Can survive at 70-1100C
Usually strict anaerobe. Some are aerobic & facultative.
Enzymes needs high temperature for their function.
Eg: Thermococcus, Desulfurococcus, Sulfolobus etc.

14. Yellowstone National Park, USA
Thermophilic Archaea
Yellowstone National Park, USA

15. Halophilic Archaea Greek Halophiles = Salt loving
Thrive in high salt concentrations ( M of NaCl).
Eg: Haladaptatus cibarius, Halalkalicoccus jeotgali.

16. Great Salt lake, Utah, USA
Halophilic Archaea
Great Salt lake, Utah, USA

17. Methanogenic Archaea Strict anaerobe.
They can reduce CO2 into Methane which creates an electrochemical gradient across cell membrane to produce ATP.
Convert Sulfur to H2S with no energy production.
Eg: Methanobrevibacter smithii, Methanobacterium, Methanococcus, Methanomicrobium.

18. Others
Archaeal Sulphate Reducers
Archeoglobus

19. Are they Pathogen???
As like Bacteria Archaea have been found in human gut, oral cavity & skin.
They can evade, colonize even stay with normal flora in human body. But their pathogenic activity has not been established.

20. Importance
Methanogenic Archaea produce methane using sewage sludge, which is a clean burning fuel.
Reduction the number of Methanogenic Archaea is associated with Crohn’s disease.
Excess methane production is contributory to global warming.

21. Halophilic Archaea are used in production of many salted food products (Soy sauce).
DNA polymerase of Thermophilc Archaea is a great interest in molecular biology.
Thermoplasma oxidize Iron sulfide (piles of coal mines) to Sulfuric acid. As a result piles become hot & acidic.

22. THANK YOU