CEE 370 Environmental Engineering Principles

Transcription

1 Updated: 12 October 2015 Print version CEE 370 Environmental Engineering Principles Lecture #13 Environmental Biology II Metabolism Reading: Davis & Masten, Chapter 3 David Reckhow CEE 370 L#13 1

2 Environmental Microbiology Types of Microorganisms Bacteria Viruses Protozoa Rotifers Fungi Metabolism Microbial Disease Microbial Growth David Reckhow CEE 370 L#13 2

3 Metabolism Biosynthesis (Anabolism) Energy Production (Catabolism) Metabolites (wastes) David Reckhow CEE 370 L#13 3

4 An overview of metabolism From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 4

5 Energy Source Light Chemicals (e.g., glucose) Storage ATP NAD+ Advantages of oxygen as a terminal electron acceptor aerobic anaerobic facultative David Reckhow CEE 370 L#13 5

6 ATP ~ ~ 7.3 kcal per mole David Reckhow CEE 370 L#13 6

7 Nicotinamide Adenine Dinucleotide David Reckhow CEE 370 L#13 7

8 Embden-Meyerhof Pathway Glucose 2 ATP 2 ADP Fructose-1,6-diphosphate Investment 2 NAD+ 2 NADH 4 ADP 4 ATP Pay-back 2 Pyruvate Net result: 2 ATPs or 14.6 kcal/mole David Reckhow CEE 370 L#13 8

9 Advantages of Aerobic Systems If we have aerobic metabolism, rather than fermentation, energy from NADH may be harvested NADH + H + 3 PO + 3ADP + 2 O NAD+ + 3ATP + H O This gives us 6 more ATPs. Then the pyruvate may be further oxidized to carbon dioxide and water, producing 30 more ATPs. The final tally is 38 ATPs or 277 kcal/mole of glucose. David Reckhow CEE 370 L#13 9

10 Pathways Generalized view of both aerobic and fermentative pathways Also showing energy transfer ATP NAD From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 10

11 Metabolic Classification Carbon Source Heterotrophic: other organic matter Autotrophic: inorganic carbon (CO 2 ) Energy Source (electron donor) Chemosynthetic: chemical oxidation Photosynthetic: light energy Terminal Electron Acceptor Aerobic: oxygen Anaerobic: nitrate, sulfate Fermentative: organic compounds David Reckhow CEE 370 L#13 11

12 Energy Flow Storage of Energy Photosynthesis Release of Energy Respiration Energy transfers by organisms are inherently inefficient 5-50% capture David Reckhow CEE 370 L#13 12

13 Aerobic Respiration A Redox reaction Oxidation of Carbon C 4 + ( H 2O) + H 2O CO2 + 4H + e Reduction of oxygen or some other terminal electron acceptor + + 4H + 4e H O2 2 2 O David Reckhow CEE 370 L#13 13

14 Other TEA: Anaerobic Respiration Nitrate Manganese Iron Sulfate C( H 2 O) + NO3 N2 + CO2 + HCO3 + H 2O C( H 2 O) + Mn Mn + CO2 + H 2O Fermentation C( H 2 O) + Fe Fe + CO2 + H 2O 2 C( H 2 O) + SO4 H 2S + CO2 + H 2O C ( H CH + CO 2 O) 4 2 methanogenesis Ecological Redox Sequence David Reckhow CEE 370 L#13 14

15 Terminal Electron Acceptors Contribution to the oxidation of organic matter Bottom waters of Onondaga Lake, NY (Effler, 1997) Sulfate Reduction 27% Nitrate Reduction 10% Iron Reduction 1% Methanogenesis 23% Aerobic 39% David Reckhow CEE 370 L#13 15

16 Energetics Principles of Gibbs Free Energy and Energy Balance can be applied to microbial growth From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 16

17 Energetics Cont. Energy Balance Cell synthesis (R c ) Energy (R a ) Electron acceptor (R d ) R = f s R c + f e R a R d From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 17

18 f-values and Yield Portions of electron donor used for: Synthesis (f s ) Energy (f e ) Values are for rapidly growing cells From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 18

19 Novel Biotransformations Oxidation Toluene dioxygenase (TDO) From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 19

20 Enzyme Chemistry Highly dependent on: Temperature ph From: Sawyer, McCarty & Parkin, 1994; also: Sawyer & McCarty, 1978 David Reckhow CEE 370 L#13 20

21 Overall Types Carbon Source Heterotrophic Autotrophic Energy Source Chemosynthetic Photosynthetic Photoheterotrophs (rare) Photoautotrophs (primary producers) Chemoheterotrophs (organotrophs) Chemoautotrophs (lithotrophs) Purple and green nonsulfur bacteria Cyanobacteria, algae & Plants Most bacteria, fungi, protozoa & animals Nitrifying, hydrogen, iron and sulfur bacteria David Reckhow CEE 370 L#13 21

22 To next lecture David Reckhow CEE 370 L#13 22