2 A. Basic Concepts Definitions Metabolism: The processes of catabolism and anabolismCatabolism: The processes by which a living organism obtains its energy and raw materials from nutrientsAnabolism: The processes by which energy and raw materials are used to build macromolecules and cellular structures (biosynthesis)
5 What are nutrients that bacteria want? C Sugar, Lipid Energy, BiosynthesisN Protein BiosynthesisO Air Energy
6 Breakdown Synthesis Proteins to Amino Acids, Starch to Glucose Amino Acids to Proteins, Glucose to Starch
7 Bacterial Metabolism ☺ Exoenzymes: Bacteria cannot transport large polymers into the cell. They must break them down into basic subunits for transport into the cell. Bacteria therefore elaborate extracellular enzymes for the degradation of carbohydrates to sugars (carbohydrases), proteins to amino acids (proteases), and lipids to fatty acids (Lipases).
8 Energy Generating Patterns After Sugars are made or obtained, they are the energy source of life.Breakdown of sugar(catabolism) different ways:Aerobic respirationAnaerobic respirationFermentation
9 Aerobic respiration Most efficient way to extract energy from glucose. Process: GlycolysisKreb CycleElectron transport chainGlycolysis: Several glycolytic pathwaysThe most common one:glucose-----> pyruvic acid + 2 NADH + 2ATP
10 B. Glycolytic Pathways4 major glycolytic pathways found in different bacteria:Embden-Meyerhoff-Parnas pathway“Classic” glycolysisFound in almost all organismsHexose monophosphate pathwayAlso found in most organismsResponsible for synthesis of pentose sugars used in nucleotide synthesisEntner-Doudoroff pathwayFound in Pseudomonas and related generaPhosphoketolase pathwayFound in Bifidobacterium and Leuconostoc
20 Anaerobic respiration Final electron acceptor : never be O2Sulfate reducer: final electron acceptor is sodium sulfate (Na2 SO4)Methane reducer: final electron acceptor is CO2Nitrate reducer : final electroon acceptor is sodium nitrate (NaNO3)O2/H2O coupling is the most oxidizing, more energy in aerobic respiration.Therefore, anaerobic is less energy efficient.
21 C. Fermentation Features of fermentation pathways Pyruvic acid is reduced to form reduced organic acids or alcohols.The final electron acceptor is a reduced derivative of pyruvic acidNADH is oxidized to form NAD: Essential for continued operation of the glycolytic pathways.O2 is not required.No additional ATP are made.Gasses (CO2 and/or H2) may be released