Lecture 11: Microbial metabolism
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How is E. coli diverse to a wide range of habitiats?
• temperatures • Uv light • low pH • salinity • etc.
How can bacteria survive for years in an environment without food
populations drops until its at a maintainable level 1. intial lag phase 2. exponential growth phase 3. death phase 4. long-term stationary phase 5.
What is chemosynthesis?
Generation of energy through chemical means (much like PHOTOsynthesis) e.g., energy from hydrothermal vents vvia sulfide
What are hydrothermal vents: black smokers
• first observed in 1977 • prod. hydrogen sulphide • sulphide and oxygen prov. E for bacteria on surface • bacteria from the start of the food chain around smoker
What is “The Lost City” hydrothermal vent
• Alkali hydrothermal vent • emits methane and hydrogen • 90foot chimneys of thick biofilms of archaea using methane and hydrogen as E sources • Serpentine mineral structure consists of interconnected chambres about 1 micro across. Possible start of life.
What are the most vital elements required for life?
C, O, N, S, P, and trace elements like Fe
What is the most essential molecule for life?
H2O
What are the two types of energy sources used?
• Phototrophism: sunlight 2. Chemotrophism: breakdown of molecules
How do higher organisms gain their energy?
• Obtained from O2 and high E carbon sources 2. Plants use high energy wavelengths of light
How do bacteria gain their energy?
More versatile • various molecules can be used instead of O2 and carbon sources • Photosynthetic bacteria can use different E wavelengths
What are the energy sources that all life use?
• ATP to ADP a. chemical energy = ~45KJ/mol b. used for transport, sensing and synthesis e.g., peptide bonds • NADH to NAD+ - another form NADPH used a. reductive energy: E0 = -0.3v, ~60KJ/mol
What are the two sides of metabolism?
• Catabolism 2. Anabolism
What are fundamental energetic processes/molecules?
• ATP and NADH are made (directly or indirectly) by OXIDATION of energy rich molecules • Oxidation releases electrons • Electrons can’t be stored indefinitely • FERMENTATION and RESPIRATION used to get rid of excess
How does respiration move about electrons?
metabolic pathways where unconnected electron donors and acceptors exchange electrons
How does fermentation move about electrons?
Electron donors and acceptors are part of the same metabolic pathway
How much energy comes from different microbial reactions?
1. Aerobic: delta G = -2870KJ mol-1 (~30ATP) 2. Anaerobic: delta G = -1930KJ mol-1 (~20ATP) 3. Lactic acid fermentation: delta G = -195KJ mol-1 (~2ATP)
Where is energy generated in bacteria?
• Cytoplasm a. E.g., Fermentation b. substrate level phosphorylation • Energy generated across the cytoplasmic membrane a. E.g., oxidative phosphorylation b. Respiration
What is the role of quinones, quinols and the cytoplasmic membrane to energy production?
• Quinols and quinones exist as mixed population in living cells • Hydrophobic molecules located in in (cytoplasmic) membrane • can carry 2e- and 2H+ without changing charge • Used to transport electrons and protons across membrane • Types include ubiquinol (aerobic), and menaquinol & duroquinol (anaerobic)