Bacterial Metabolism

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Bacterial Metabolism

• Metabolism
• Sum up all the chemical processes that occur
  within a cell
• 1. Anabolism Synthesis of more complex compounds
  and use of energy
• 2. Catabolism Break down a substrate and capture
  energy

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Overview of cell metabolism
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Bacterial Metabolism

• Autotroph
• Photosynthetic bacterial
• Chemoautotrophic bacteria
• Heterotroph
• Parasite
• Saprophyte

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Energy Generating Patterns

• After Sugars are made or obtained, they are the
  energy source of life.
• Breakdown of sugar(catabolism) different ways
• Aerobic respiration
• Anaerobic respiration
• Fermentation

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Photosynthesis

• (1) Higher plants
• Light reaction
• Photolysis of H2O produce ATP and NADPH
• Two photosystem (I II)
• Dark fixation use the production from light
  reaction (ATP and NADPH) to fix CO2
• Reaction
• 6CO2 6H2O -----gt C6H12O6 6O2
• (Light and chloroplast)

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Bacteria Photosynthesis

• i. Only one photosystem can not do photolysis of
  H2O
• ii. H2O not the source of electron donor
• iii. O2 never formed as a product
• iv. Bacterial chlorophyll absorb light at longer
• W.L.
• v. Similar CO2 fixation
• vi. Only has cyclic photophosphorylation

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How the Bacteria synthesize NADPH

• Grow in the presence of the H2 gas
• H2 NADP -------------? NADPH2
• hydrogenase
• Reverse the electron flow in the e- transport
  chain
• H2S S
• S NADP--------? SO4-2 NADPH2
• Succinate Fumarate
• Simple non-cyclic photosynthetic e- flow

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Chlorophyll a and bacteriochlophyll a(1)
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Chlorophyll a and bacteriochlophyll a(2)
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Anoxygenic photosynthesis
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Anoxygenic versus oxygenic phototrophs(2)
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Anoxygenic versus oxygenic phototrophs(1)
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Photosynthetic bacteria

• (1) Chlorobium-green sulfur bacteria
• Use green pigment chlorophyll
• Use H2S (hydrogen sulfide), S (sulfur), Na2S2O3
  (sodium thiosulfate) and H2 as e- donors.
• (2) Chromatium-purple sulfur bacteria
• Use purple carotenoid pigment, same e-donors
• (3) Rhodospirillum-non sulfur purple bacteria
• Use H2 and other organic compounds such as
  isopropanol etc, as e-donors.
• Reaction CO2 2H2A -----gt CH20 H20 2A
• A is not O

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Chemautotroph

• Some bacteria use O2 in the air to oxidize
  inorganic compounds and produce ATP (energy). The
  energy is enough to convert CO2 into organic
  material needed for cell growth.
• Examples
• Thiobacillus (sulfur S)
• Nitorsomonas (ammonia)
• Nitrobacter (nitrite)
• Various genera (hydrogen etc.)

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Aerobic respiration

• Most efficient way to extract energy from
  glucose.
• Process Glycolysis
• Kreb Cycle
• Electron transport chain
• Glycolysis Several glycolytic pathways
• The most common one
• glucose-----gt pyruvic acid 2 NADH 2ATP

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Aerobic respiration

• Euk.
• glucose -----gt G-6-P-----gtF-6-P-----gt
• ... 2 pyruvate 2ATP 2NADH
• Prok.
• glucose-----gt G-6-P------gtF-6-P
• Process take places during transport of the
  substrate. Phosphate is from phosphoenolpyruvate
  (PEP)
• .....-----gt 2 pyruvate 2ATP 2NADH

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• Kreb cycle
• Pyruvate 4NAD FAD -----gt
• 3CO2 4NADH FADH
• GDP Pi -----gt GTP
• GTP ADP -----gt ATP GDP
• Electron trasnport Chain
• 4HADH -----gt 12 ATP
• FADH ------gt 2 ATP Total 15 ATP
  
• Glycolysis -----gt 8 ATP
• Total equation
• C6H12O6 6O2 ------gt 6CO2 6H2O 38 ATP

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Generation of a proton-motive force(1)
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Generation of a proton-motive force(2)
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Mechanism of ATPase
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Anaerobic respiration

• Final electron acceptor never be O2
• Sulfate reducer final electron acceptor is
  sodium sulfate (Na2 SO4)
• Methane reducer final electron acceptor is CO2
• Nitrate reducer final electroon acceptor is
  sodium nitrate (NaNO3)
• O2/H2O coupling is the most oxidizing, more
  energy in aerobic respiration.
• Therefore, anaerobic is less energy efficient.

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Fermentation

• Glycosis
• Glucose -----gt2 Pyruvate 2ATP 2NADH
• Fermentation pathways
• a. Homolactic acid F.
• P.A -----gt Lactic Acid
• eg. Streptococci, Lactobacilli
• b.Alcoholic F.
• P.A -----gt Ethyl alcohol
• eg. yeast

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• c. Mixed acid fermentation
• P.A -----gt lactic acid
• acetic acid
• H2 CO2
• succinic acid
• ethyl alcohol
• eg. E.coli and some enterbacter
• d. Butylene-glycol F.
• P.A -----gt 2,3, butylene glycol
• eg. Pseudomonas
• e. Propionic acid F.
• P.A -----gt 2 propionic acid
• eg. Propionibacterium

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Alternative energy generating patterns(1)
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Alternative energy generating patterns(2)
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Alternative energy generating patterns(3)
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Alternative energy generating patterns(4)
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Energy/carbon classes of organisms
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Chlorophyll a and bacteriochlophyll a(3)
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Comparison of reaction centers of anoxyphototrophs
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