METABOLISM

Why Study Metabolism?

Classification of bacteria

– Oxygen Tolerance

– Biochemical reactions

• Acids, Ammonia, Gases Fermentation Products

– Food Products

• Yogurt, Sour Cream, Bread, Alcohol

– Commercial Products

• Citric Acid, Plastics Environmental Cleanup

Ying & Yang of Metabolism

Metabolism = Anabolism + Catabolism

Photosynthesis requires Respiration

Respiration requires Photosynthesis

Energy Production = Energy Consumption

BreakdownProteins to Amino Acids, Starch to Glucose

SynthesisAmino Acids to Proteins, Glucose to Starch

Chapter 5

Overview of Metabolism

Source of Energy (Photo- vs. Chemotroph)– Source of Electrons– Carrier of Electrons– Final Electron Acceptor

Source of Carbon (Auto- vs. Heterotroph)– Auto- : Carbon Dioxide– Hetero- : Organic Compounds

Electron Carriers

Photosynthesis– NADP + H to NADPH

Respiration– NAD + H to NADH– FAD + H to FADH

Contain Niacin and Riboflavin– Vitamins, not stable– Can’t store these molecules

Movement of Electrons

Chemical reactions

Oxidation Reactions

Reduction Reactions

Reactions Coupled Redox reactions

Chapter 5

Example of Redox Equations

Final Electron Acceptor

Photosynthesis– CO2 + H’s to CH2O

– Stores energy Respiration

– Aerobic• 1/2 O2 + H 2 to H2O

– Anaerobic• Fermentation

Chapter 5

Examples

ATP ADP + P – Oxidation, release energy

ADP + P ATP– Reduction, stores energy

NAD + H NADH FADH FAD + H NH4 + 11/

2O2 NO2- +H2O + 2H + ATP

2H2 + O2 2H2 O

Respiration

Overview;– Glucose to Carbon dioxide + Water +Energy

– C6H12O6 + O2 6CO2 + 6H2O + 38 ATP

– Glucose is highly reduced; contains energy– Oxygen receives the electrons to form energy

4 separate reactions– Glycolysis, Transition Reaction, Krebs Cycle,

Electron Transport, Chemiosomosis Requires Oxygen

Biochemical Pathways of Energy Metabolism

Series of controlled reactions rather than in a single burst.

Chapter 5

Glycolysis- 10 steps

Glucose is Phosphorylated to form Fructose 1,6-diphosphate

Split to form 2 Glyceraldehyde 3-phosphate Final Products are:

– 2 Pyruvic Acid (C3H4O3)

• Compare to original glucose - C6H12O6

– 2 NADH– 2 ATP

Carbohydrate metabolism

Pentose Phosphate Pathway – hexose monophosphate shunt

Operates simultaneously with glycolysis Provides a means for the breakdown of

5 carbon sugars as well as glucose

Carbohydrate Metabolism

EDP is still another pathway for oxidizing glucose to pyruvic acid

Yield 1 ATP

Used by Gram negatives (e.g. Rhizobium, Psuedomonas, Agrobacterium), usually not by Gram positives.

The Pentose Phosphate pathway (hexose monophosphate shunt) is used to metabolize five-carbon sugars; one ATP and 2 NADPH molecules are produced from oxidation of one glucose molecule. Produces intermediates for nucleotide and nucleic acid synthesis, glucose synthesis from CO2 in photosynthesis, and some amino acids.

Chapter 5

Fermentation Products from Pyruvate Homolactic = Lactic Acid

– Yogurt, Lactobacillus Alcohol + CO2

Propionic Acid Butyric Acid Acetic Acid Succinic Acid Butylene to Acetoin

– basis for VP Test (Vogues-Proskauer)

Chapter 5

Fermentation Products Alcohol and Carbon Dioxide

– Yeast mostly Lactic Acid

– Humans, muscles without oxygen– Bacteria (Lactobacillus-yogurt)

Butyric Acid– Rancid butter, Clostridium-gangrene

Acetoin – Butanediol fermentation in Klebsiella

Propionic Acid – Swiss Cheese

Chapter 5

Fermentation in Yeast

Chapter 5

Fermentation in Muscle

Fermentation of Carbohydrates

Glucose Pyruvic Acid fermentation or respiration

Release energy from sugars or other organic molecules such as amino acids, organic acids, purines and pyrimidines

Does not require oxygen Does not require an electron transport

chain

Fermentation of Carbohydrates

Uses an organic molecule as the final electron acceptor

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Swiss cheese.

Beer, wine, bread.

Flatulence!

LAB & our own muscles.

Fermentation

Products – ethanol and carbon dioxide Brewing and wine making are anaerobic

processes if oxygen is present further oxidation will occur

Respiration

Is an ATP generating process in which chemical compounds are oxidized and the final electron acceptor is almost always an inorganic molecule

Electron transport chain – readily accept electrons from one compound and pass them to another

ATP generated by oxidative phosphorylation

Respiration

Oxidize organic molecules completely to carbon dioxide

ATP yield greater in respiration than in fermentation

Krebs Cycle

As acetyl CoA enters the Krebs cycle, CoA detaches from the acetyl group and then can pick up more acetyl groups for the next Krebs cycle

Series of redox reactions Yield 38 ATP

Protein Catabolism

Require extracellular enzymes – proteases and peptidases

Deaminate amino acids Decarboxylation

Lipid Catabolism

Fats fatty acids + glycerol Requires lipases Convert glycerol into dihydroxyacetone

phosphate Fatty acids catabolized by beta

oxidation

Energy Utilization

Microbes use ATP to provide energy for the transport of substances across plasma membranes

For flagellar motion Biosynthesis of new cell components

Biosynthesis of Polysaccharides

Bacteria synthesize glycogen from adenosine diphosphoglucose – ADPG

Synthesize capsular material

Biosynthesis of Lipids

Microbes synthesize lipids, by uniting glycerol and fatty acids

Structural components of plasma membrane and Gram – cell wall

Lipids serve as storage forms of energy

Biosynthesis of Amino Acids

Required for protein synthesis E. coli – synthesize all the amino acids

they need Other microbes require some preformed

aa from the environment in order to metabolize proteins

Krebs cycle source of precursors for aa

Biosynthesis of Amino Acids

Other sources of precursors are derived from the pentose phosphate pathway and the EDP

AA building blocks for proteins (toxins)

Biosynthesis of Purines & Pyrimidines

Sugars composing nucleotides are derived from either the PPP or the EDP

Aspartic acid, glycine and glutamine play an essential role in the biosynthesis of purines and pyrimidines

The C and N atoms derived from these aa form the backbone of the purines and pyrimidines

Integration of Metabolism

Anabolic and catabolic reactions are integrated through a group of common intermediates

Krebs cycle – operate in both anabolic and catabolic reactions produce intermediates that lead to the synthesis of amino acids, fatty acids and glycerol – amphibolic pathways

Chemo Organic Autotrophs

• Two types – Chemo organic autotroph • Derives their energy from organic compounds and their carbon source from inorganic compounds – Lithoautotrophs • Neither sunlight nor organics used, rather it relies totally on inorganics

Photoautotroph

• Derive their energy from sunlight • Transform light rays into chemical energy • Primary producers of organic matter for heterotrophs • Primary producers of oxygen • Ex. Algae, plants, some bacteria

Chemoheterotrophs

Derive both carbon and energy from organic compounds – Saprobic • decomposers of plant litter, animal

matter, and dead microbes – Parasitic • Live in or on the body of a host

Iron precipitation at near an iron mine: Iron rich (Fe2+) anaerobic waters become oxygenated at the surface

Precipitated iron seeping from an iron bog in Colorado Bog iron ore from Poland

Bog iron ore from coastal Virginia swamps