BACTERIAL METABOLISM.ppt

BACTERIAL METABOLISM Why study bacterial metabolism? To understand and to know : 1- Drugs; interfering with bacterial metabolism (Infection control) 2- To prepare several artifiicial culture media: Isolation of microbes (in laboratory) 3- Biochemical reactions: Identification of bacteria (in labor...

BACTERIAL METABOLISM Why study bacterial metabolism? To understand and to know : 1- Drugs; interfering with bacterial metabolism (Infection control) 2- To prepare several artifiicial culture media: Isolation of microbes (in laboratory) 3- Biochemical reactions: Identification of bacteria (in laboratory). 4- Metabolic by – products of bacteria Inhibition of pathogenic microbes (acids etc….) 5- Toxins, enzymes: Infectious disease mechanisms Nutrition Pathways of Bacteria Capture of nutrients by: 1- Simple diffusion 2- Facilitated diffusion (Compound + carrier protein entrence) 3- Active transport into bacterial cell: Energy yielded from ATP or proton gradient 4- Group translocation In the absence of oxygen (Transport of glucose by being phosphorylated.) Metabolism in the cell 1- Embden – Meyerhof pathway 2- Pentose – Phosphate pathway 3- Krebs cycle 4- Entner – Duodoroff pathway Metabolism Catabolism Anabolism *Degradation of * Biosynthesis complex molecules * Energy consuming *Energy generating (endergonic) (exergonic) (ATP synthesis) (KREBS etc….) SOME PRINCIPLES Each Pathway: series of chemical changes A rxn B rxnC rxnD rxn 1 2 A E B,C,D E 3 the starting substrate the final substrate metabolic intermediates 4 In all metabolic reactions, ês are transferred  Oxidation Reduction loss of electrons gain in electrons  Highly reduced compounds are more energy – rich !! C6 H12 O6 6 CO2 + 6 H2O +Energy (glucose) (energy poor) ( energy rich)   ATP ADP cell’s energy carrier cell’s energy acceptor ês are transferred to coenzymes (NAD, NADP, FAD)  ês are usually released in the form of Hydrogen atoms (H)  NADP+ NAD + NADPH+H NADH+H oxidized and (+) charged reduced (accepted one pair of ês from 2 H atoms) CATABOLISM: FOR DEGRADATION OF LARGE MOLECUES Fermentation & Respiration Catabolism is the set of destrucrive pathways that breaks down large molecules (such as polysaccharides, lipids, nucleic acids, and proteins) into smaller units (such as monosaccharides, fatty acids, nucleotides, and amino acids, ) that are either oxidized to release energy or used in other anabolic CATABOLISM (FOR DESTRUCTION)  The compound ?????****  that finally acquires the ês       from NADH+H determines **** whether a bacterium is: fermentative or respiratory Anaerobic Facultative anaerobic Aerobic Fermentation Begins with degradation of Glucose...... Pyruvic acid  Conversion of pyruvic acid to organic products x Facultatively anaerobic microbes ******** (when O₂ is consumed) different from fermentation Fermentation:    A kind of anaerobic respiration***** Does not require oxygen NO Kreb’s cycle or ETC used Less (2 ATP ) produced !!! Examples: a) Pyruvic acid b) Pyruvic acid Pyruvic acid Ethly alcohol + CO2 (yeasts) Lactic acid (homolactic ferm.) Lactic acid + acetic acid + succinic acid + formic acid + CO2 (E. coli) (mixed acid ferm.) c) Pyruvic acid Acetone, isopropanol, butyric acid, butanol (strict anaerobes) d) Pyruvic acid Acetoin (Enterobacter, Pseudomonas) e) Pyruvic acid Propionic acid + CO 2 (Propionibacterium acnes (Cutibacterium) Fermentation in Human COLON MALODOR, AMINOACID FERMENTATION  Mixed Amino Acid Fermentation Clostridium spp.  In: anaerobic, protein rich environments  Fermentation of: Alanine / Glycine mixture  Generation of: NH3, H2S, fatty acids, and CO2,  Horrible smell of gangrenous lesions!!!  RESPIRATION: in membrane AEROBIC RESPIRATON     • Produces 38 ATP molecules in prokaryotes (bacteria) – 10 NADH………….. 30 ATP – 2 FADH 2……………. 4 ATP – Glycolysis/Kreb’s … 4 ATP     • Krebs cycle • Electron transport chain (ETC) – Carrier molecules that transport electrons resulting in a stepwise release of energy that is used to form ATP  – Final electron (é) acceptor is O2  which forms H2O ANAEROBIC RESPIRATION Facultative anaerobes, meaning they can switch between aerobic respiration and anaerobic pathways (fermentation or anaerobic respiration...) Most of the human related bacteria are Facultative anaerobic (Staphylococci, Escherichia coli, …..) A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. In true anaerobic respiration: Final ê acceptor is: inorganic molecule other than O 2 (CO2, sulfate, nitrate....) Respiratory chain is: shorter Fewer ATP, fewer NADH+H are produced Anaerobic bacteria possess lower energy (poor growth on artificial media) !! Aerobic Bacteria vs Anaerobic Bacteria Following are the important differences between aerobic and anaerobic bacteria: Difference between Aerobic and Anaerobic AEROBIC ANAEROBIC Need oxygen to survive Do not require oxygen to survive Produce more energy Produce less energy Molecular oxygen is the final electron acceptor Carbon dioxide, sulfur, nitrate, fumarate or ferric is the final electron acceptor Bacteria are seen on the surface of the liquid Bacteria are settled at the bottom of the liquid Example: Mycobacterium tuberculosis Example: Clostridium brain abscesse dental infections, aspiration pneumonia, lung abscesses, bite infections (animal/human), abdominal abscesses necrotizing infections of soft tissue Anaerobic infections Gas gangren by Anaerobic bacteria ANABOLISM (FOR BIOSYNTHESIS)  Energy utilization  Assimilaton of simple compounds monomers (monosaccharides, fatty acids, nucleotides, and amino acids, assembly of proteins, nucleic acids, polysaccharides, lipids. (biosynthesis) (production of macromolecules Peptidoglycan BioSynthesis 1   In the cytosol Glucose, NAG – UDP (uridin diphosphate) ATP,UTP  Some NAG – UDP NAM – UDP (PEP energy)  Pentapeptid chain + NAM – UDP (by ATP) • • • • • L-ala D-glu L-Iys (DAP), D-ala D-ala Pedtidoglycan BioSynthesis 2  NAM - pentapeptide – UDP (removed) NAM – pentapeptide – Lipid carrier (undecaprenol)  Some NAG-UDP-NAM- Pentapeptide - undecaprenol : i) passed through cell membrane ii) integrated into cell wall  NAG-NAM-NAG-NAM-NAG-NAM-NAG-NAM (B 1-4glycoside and penta glycine bridge)*