LM10-2 - SelectedArchaeaprokaryotes

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Selected Archaea prokaryotes • Archaea: Several phyla divided into 5 physiologically  distinct groups • Phylum Crenarchaeota – mesophilic members main  oceanic Archael species; many thermophiles and  hyperthermophiles also in this phylum • Phylum Euryarchaeota – Diverse group containing  methanogens, extreme halophiles, sulfur  metabolizers 1
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Metabolism – methanogenesis in Euryarchaeota  • Substrates for anaerobic  methanogenesis are usually H 2   + CO 2  or formate, others  sometimes used • ATP production is by PMF  generation, but details remain  unclear • Methanogens found in marine  sediments, in swamps, in  protozoa, rumens of cows • One cow can produce 200-400  liters of CH 4 /day CH 4  potent greenhouse gas,  but clean-burning fuel 2
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Halobacteria (Figs. 18.13, 18.14) • Absolutely dependent  on high salt (best  growth at 3-4 M) H. salinarium  (left)  has purple membrane  composed of  bacteriorhodopsin  (light-driven proton  pump), halorhodopsin  (light driven  transporter) and 2  sensory rhodopsins  that control movement  in response to red and  blue light 3
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Bacteria • 24 phyla included in Bergey’s; 22 Gram-negative  and 2 Gram-positive, but DNA analyses suggests  at least 40 Phyla  • Classification in Bergey’s is according to SSU (16S  rRNA) sequences, GC content, metabolism, habitat  and phenotype 4
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D. radiodurans  resistant to  extreme desiccation and high  levels of radiation (both  produce DS-DNA breaks) • Are Gram+, but have outer  membrane and ornithine in  peptidyl x-links, lack teichoic  acid • Nucleoids from different  parts of tetrad fuse to  provide template for fixing  DS-DNA breaks • Found in many sources,  natural habitat unknown 5
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This note was uploaded on 03/31/2010 for the course MCB 3020 taught by Professor Ogden during the Spring '08 term at University of Florida.

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LM10-2 - SelectedArchaeaprokaryotes

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