Introduction to Prokaryotes

Prokaryotes is divided into two domains, one is bacteria while the other one is archaea. Proteobacteria is a large group of gram negative bacteria and includes wide variety of pathogens. They are either facultative anaerobe or obligate anaerobe, meaning they do not depend on oxygen to live. Furthermore, proteobacteria is defined based on the rRNA.

Below are six classes of proteobacteria and their respective examples:

• Alphaproteobacteria     (Brucella, Rhizobium for nitrogen fixation, Wolbachia)
• Betaproteobacteria       (Bordetella that cause whooping cough, Neisseria, Nitrosomonas)
• Gammaproteobacteria  (Escherichia, Shigella, Salmonella, Vibrio, Pseudomonas)
• Deltaproteobacteria      ( Desulfovibrio, Geobacter, Bdellovibrio)
• Epsilonproteobacteria  (Helicobacter the causative agent of peptic ulcer, Wolinella)
• Zetaproteobacteria       (Mariprofundus ferrooxydans)

On the other hand, gram positive bacteria that can form endospore are Bacillus sp. and Clostridium sp.. Streptomyces sp. produce antibiotic called streptomycin.

Lyme disease

1. Lyme disease is a infectious disease caused by the bite of a tick infected with Borellia burgdorferi.
2. After biting, an expanding of bull's eye rash develops on skin.
3. This disease is not contagious from affected person to someone else.
4. The symptoms are joint swelling and muscle pain.
5. Preventions are wearing long sleeved shirt and long pants tucked into socks, special care in handling outdoor pets and avoid tick habitats such as brushy or overgrown grass habitats.
6. Treatment with antibiotic at early stage is applicable. Example of antibiotics are deoxycycline, amoxicillin and cefuroxime.

Syphilis disease

1. A sexually transmitted disease caused by Treponema pallidum.
2. Antibiotic is available for early stage.
3. Often, syphilis does not have any symptoms.
4. Condom can be used to prevent spreading of syphilis disease.

Purple sulphur bacteria

1. Proteobacteria.
2. Habitat: stagnant water or place with high concentration of hydrogen sulphide.
3. Anaerobic or microaerophilic.
4. Use hydrogen sulphide as reducing agent.
5. Genera: Chromatium sp., Ectothiorhodospira sp.
6. Anoxygenic photosynthesis, which means no oxygen is produced after photosynthesis.

Purple non sulphur bacteria

1. In stead of using hydrogen sulphide, they use hydrogen as reducing agent.
2. High concentration of sulphur will kill them compare to purple sulphur and green sulphur bacteria.
3. Too much hydrogen sulphide is toxic to them.
4. Anoxygenic photosynthesis as water is not used as electron donor.
5. Example: Rhodospirillum sp., Rhodobacter sp., Rhodobium sp.

Green sulphur bacteria

1. Obligate anaerobic photoautotrophic bacteria.
2. Also known as Chlorobiacaee.
3. Non motile.
4. Require reduced sulphur compounds like sulphide.
5. Habitat: Volcanic hot spring, deep in freshwater lake
6. Genera: Chlorobium sp., Prosthecochloris sp., Chloroherpeton sp.
7. Anoxygenic photosynthesis

   

   Comparison between archaea, bacteria and eukaryotes

    

 



Difference of membrane lipid of bacteria and archaea