Chapter 5: Microbial Metabolism

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Chapter 5 Microbial Metabolism
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METABOLISM

• Sum of all chemical rxns within a living
  organism
• Release energy
• Require energy

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• CATABOLIC REACTION (breakdown)
• Breakdown of complex organic compounds into
  simpler ones
• Generally hydrolytic reactions (water used to
  break bonds)
• Exergonic (produce more energy than consume)
• Provide building blocks for anabolic rxns and
  energy needed to drive anabolic rxns

• ANABOLIC REACTIONS (build)
• Building of complex organic molecules from
  simpler ones
• Generally dehydration synthesis
• Endergonic (consume more energy than produce)

ATP ltgt ADP Pi energy
Rxns all determined by enzymes and coupled
together
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Metabolism Overview
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But reactions happen very SLOWLY by
themselves....to make reactions go FASTER we
need.........
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ENZYMES !
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Enzymes

• Biological catalysts
• Each act on a specific substance (substrate)
• Has active site for substrate to bind to
• loading dock
• Each catalyzes only one reaction
• Sensitive to temperature, pH, concentration
• Can become denatured
• All end in -ase

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Enzymes

• Large 3-D globular molecule
• Composed of two parts
• 1. Protein portion (apoenzyme)
• Inactive if alone
• 2. Nonprotein component (cofactor)
• Ions of iron, zinc, magnesium or calcium
• If organic coenzyme
• Together with the apoenzyme and cofactor active
  enzyme (holoenzyme)

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Enzymes Steps in a Reaction
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Enzymes Overview
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HOW DO YOU CONTROL GROWTH OF BACTERIA??
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CONTROL THEIR ENZYMES!
(Using inhibitors)
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Inhibitors

• Competitive Inhibitors
• Fill the active site of an enzyme and compete
  with the normal substrate for the active site
• Similar shape and chemical structure
• Does not produce products
• Example Sulfa drug
• Animation CD

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Inhibitors

• Noncompetitive Inhibitors
• Do not compete with the substrate instead
  interact with another part of the enzyme
• Binds and causes the active site to change its
  shape, making it nonfunctional
• Allosteric inhibition other space
• Animation CD

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Carbohydrate Catabolism

• Most microorganisms use carbon as primary energy
  source
• Oxidation of glucose
• Cellular Respiration
• Glycolysis
• Krebs cycle
• Electron Transport Chain
• Lots of energy made
• Fermentation
• Glycolysis
• Products Alcohol or lactic acid
• Little energy made

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Fermentation

• Releases energy from sugars or other organic
  molecules
• Does not require oxygen
• Produces only a small amount of ATP

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• Alcohol Fermentation
• Saccharomyces (yeast)

• Lactic Acid Fermentation
• Streptococcus
• Lactobacillus
• Bacillus

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Photosynthesis
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• Conversion of light energy into chemical energy
• Chemical energy then used to convert CO2 into
  sugars (carbon fixation)
• Cyanobacteria

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REVIEW

• Cellular Respiration
• Aerobic
• Carbon
• Fermentation
• Anaerobic
• Carbon
• Photosynthesis
• Carbon Fixation
• Light energy

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Classifying Bacteria-Nutritional Pattern

• HOW DO THEY GET
• ENERGY?
• Phototrophs use light as primary energy source
• Chemotrophs use reactions of inorganic or
  organic compounds for energy

• HOW DO THEY GET
• CARBON?
• Autotrophs CO2 as principle carbon source
• Heterotrophs organic carbon source

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PHOTOAUTOTROPHS
Chromatium - Purple Bacteria Found in
sulfide- containing freshwater habitats

• Energy light
• Carbon CO2
• Examples cyanobacteria
• (photosynthesis)
• Green and Purple Bacteria - use sulfur or
  hydrogen gas to reduce CO2 and make organic
  compounds

• Chlorobium-
• Green Bacteria
• found in hot
• springs, cold lakes
• and sediments

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PHOTOHETEROTROPHS

• Energy Light
• Carbon organic compounds
• Examples
• Green nonsulfur bacteria
• Chloroflexus
• (found in hot springs, lakes, hyersaline
  environments)
• Purple nonsulfur bacteria
• Rhodopseudomonas
• (found in soil and marine environments)

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CHEMOAUTOTROPHS

• Energy inorganic compounds
• Ex H2S, S, NH3, H2, CO
• Carbon CO2
• -fix CO2
• Example
• Beggiatoa - use H2S, found in soil, sulfur
  springs, mud layers of lakes,

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CHEMOHETEROTROPHS

• Energy organic compounds
• Ex glucose
• use the electrons from H-atoms as energy source
• Carbon organic compound
• Hard to distinguish-use the same compound
• Example
• Streptococcus pneumonia - fermentation

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• http//people.eku.edu/ritchisong/RITCHISO/energyfl
  owchart.jpg
• http//www.hepafilters.com/images/microbes.jpg
• http//www.bio12.com/ch6/RemedialEnzymes_files/ima
  ge007.jpg
• http//classes.midlandstech.edu/carterp/Courses/bi
  o225/chap05/Slide13.GIF