1. Chapter 5: Microbial Metabolism

2. METABOLISM Sum of all chemical rxn’s within a living organism
Release energy
Require energy

3. 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 <=> ADP + Pi + energy
Rxn’s all determined by enzymes
and coupled together

4. [insert Metabolism_Overview.jpg]
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5. But reactions happen very SLOWLY by themselves
But reactions happen very SLOWLY by themselves....to make reactions go FASTER we need

6. ENZYMES !

7. 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

8. 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)
Enzymes

9. Enzymes: Steps in a Reaction
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10. [insert Enzymes_Overview.jpg]
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11. HOW DO YOU CONTROL GROWTH OF BACTERIA??

12. CONTROL THEIR ENZYMES!
(Using inhibitors)

13. 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

14. 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

15. 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
Products: Alcohol or lactic acid
Little energy made

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

18. Alcohol Fermentation:
Saccharomyces (yeast)
Lactic Acid Fermentation
Streptococcus
Lactobacillus
Bacillus

19. Photosynthesis

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

21. REVIEW Cellular Respiration Fermentation Photosynthesis Aerobic Carbon
Anaerobic
Photosynthesis
Carbon Fixation
Light energy

22. 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

23. PHOTOAUTOTROPHS Energy: light Carbon: CO2 Examples: cyanobacteria
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

24. 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)

25. 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,

26. 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