Microbial Metabolism

1. Microbial Metabolism Chapter 5

2. Metabolism - all of the chemical reactions within a living organism • 1. Catabolism ( Catabolic ) • breakdown of complex organic molecules into simpler compounds • releases ENERGY • 2. Anabolism ( Anabolic ) • the building of complex organic molecules from simpler ones • requires ENERGY

3. Enzymes - catalysts thatspeed up and direct chemical reactions • A. Enzymes are substrate specific • Lipases Lipids • Sucrases Sucrose • Ureases Urea • Proteases Proteins • DNases DNA

4. Enzyme Specificity can be explained by the Lock and Key Theory E + S -----> ES ------> E + P

5. Naming of Enzymes - most are named by adding “ase” to the substrate • Sucrose Sucrase • Lipids Lipase • DNA DNase • Proteins Protease • removes a Hydrogen Dehydrogenase • removes a phosphate phosphotase

6. Naming of Enzymes • Grouped based on type of reaction they catalyze • 1. Oxidoreductases oxidation & reduction • 2. Hydrolases hydrolysis • 3. Ligases synthesis

7. Enzyme Components 2 Parts 1. Apoenzyme - protein portion 2. Coenzyme (cofactor) - non-protein Holoenzyme - whole enzyme

8. Coenzymes • Many are derived from vitamins • 1. Niacin • NAD (Nicotinamide adenine dinucleotide) • 2. Riboflavin • FAD (Flavin adenine dinucleotide) • 3. Pantothenic Acid • CoEnzyme A

9. Factors that Influence Enzymatic Activity Denaturation of an Active Protein

13. Inhibitors can effect enzymatic activity 1. Competitive Inhibitors 2. Noncompetitive Inhibitors

14. Competitive Inhibitors -compete for the active site • 1. Penicillin • competes for the active site on the enzyme involved in the synthesis of the pentaglycine crossbridge • 2. Sulfanilamide (Sulfa Drugs) • competes for the active site on the enzyme that converts PABA into Folic Acid • Folic Acid - required for the synthesis of DNA and RNA Selective Toxicity

15. Non-competitive Inhibitors - attach to an allosteric site

17. Energy Production • 1. Oxidation • refers to the loss of Hydrogens and or electrons • 2. Reduction • the gain of Hydrogens and or electrons NAD Cycle

18. Carbohydrate Catabolism • Microorganisms oxidize carbohydrates as their primary source of energy • Glucose - most common energy source • Energy obtained from Glucose by: • Respiration • Fermentation

19. Aerobic Cellular Respiration • Electrons released by oxidation are passed down an Electron Transport System with oxygen being the Final Electron Acceptor • General Equation: • Glucose + oxygen----> Carbon dioxide + water • ATP

20. Chemical Equation • C6H12O6 + 6 O2 -------> 6 CO2 + 6 H2O • 38 ADP + 38 P 38 ATP

21. Aerobic Cellular Respiration • 4 subpathways • 1. Glycolysis • 2. Transition Reaction • 3. Kreb’s Cycle • 4. Electron Transport System

22. 1. Glycolysis (splitting of sugar) • Oxidation of Glucose into 2 molecules of Pyruvic acid • Embden-Meyerhof Pathway • End Products of Glycolysis: • 2 Pyruvic acid • 2 NADH2 • 2 ATP

23. 2. Transition Reaction • Connects Glycolysis to Krebs Cycle • End Products: • 2 Acetyl CoEnzyme A • 2 CO2 • 2 NADH2

24. 3. Krebs Cycle (Citric Acid Cycle) • Series of chemical reactions that begin and end with citric acid • Products: • 2 ATP • 6 NADH2 • 2 FADH2 • 4 CO2

25. 4. Electron Transport System • Occurs within the cell membrane of Bacteria • Chemiosomotic Model of Mitchell • 34 ATP

26. NADH2 Glycolysis 2 T. R. 2 Krebs Cycle 6 Total 10 10 x 3 = 30 ATP FADH2 Glycolysis 0 T.R. 0 Krebs Cycle 2 Total 2 2 x 2 = 4 ATP How 34 ATP from E.T.S. ?3 ATP for each NADH22 ATP for each FADH2

27. Total ATP production for the complete oxidation of 1 molecule of glucose in Aerobic Respiration • ATP • Glycolysis 2 • Transition Reaction 0 • Krebs Cycle 2 • E.T.S. 34 • Total 38 ATP

28. Anaerobic Respiration • Electrons released by oxidation are passed down an E.T.S., but oxygen is not the final electron acceptor • Nitrate (NO3-) ----> Nitrite (NO2-) • Sulfate (SO24-) ----> Hydrogen Sulfide (H2S) • Carbonate (CO24-) -----> Methane (CH4)

29. Fermentation • Anaerobic process that does not use the E.T.S. Usually involves the incomplete oxidation of a carbohydrate which then becomes the final electron acceptor. • Glycolysis - plus an additional step

30. Fermentation may result in numerous end products 1. Type of organism 2. Original substrate 3. Enzymes that are present and active

31. 1. Lactic Acid Fermenation • Only 2 ATP • End Product - Lactic Acid • Food Spoilage • Food Production • Yogurt - Milk • Pickles - Cucumbers • Sauerkraut - Cabbage • 2 Genera: • Streptococcus • Lactobacillus

32. 2. Alcohol Fermentation • Only 2 ATP • End products: • alcohol • CO2 • Alcoholic Beverages • Bread dough to rise • Saccharomyces cerevisiae (Yeast)

33. 3. Mixed - Acid Fermentation • Only 2 ATP • End products - “FALSE” • Escherichia coli and other enterics

34. Propionic Acid Fermentation • Only 2 ATP • End Products: • Propionic acid • CO2 • Propionibacterium sp.

35. Fermentation End Products

36. Lipid Catabolism

37. Protein Catabolism

38. Photosynthesis - conversion of light energy from the sun into chemical energy • Chemical energy is used to reduce CO2 to sugar (CH2O) • Carbon Fixation - recycling of carbon in the environment (Life as we known is dependant on this) • Photosynthesis • Green Plants • Algae • Cyanobacteria

39. Chemical Equation • 6 CO2 + 6 H2O + sunlight -----> C6H12O6 + 6 O2 • 2 Parts: • 1. Light Reaction • 2. Dark Reaction

40. Light Reaction • Non-Cyclic Photophosphorylation • O2 • ATP • NADPH2 • Light Reaction (simplified)

41. 2. Dark Reaction