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1 L Mikrobiologie Julia Vorholt Lecture 8: Nov 12, 2012 Brock Biology of Microorganisms, Twelfth Edition Madigan / Martinko / Dunlap / Clark

2 1) Nutrients and microbial growth 2) Introduction to principles of metabolism 3) Chemoorganotrophy 4) Chemolithotrophy 5) Phototrophy 6) Autotrophy, nitrogen fixation 7) Global carbon, nitrogen, sulfur cycles Brock Biology of Microorganisms, Twelfth Edition Madigan / Martinko / Dunlap / Clark

Glycolysis and Citric Acid Cycle Glucose Substrate-levelphosphorylation Pyruvate Acetyl-CoA C 2 C 4 2 lactate Electron transport-coupled phosphorylation C 5 2

3 Glycolysis and Citric Acid Cycle Glucose Substrate-levelphosphorylation Pyruvate Acetyl-CoA C 2 C 4 2 lactate Electron transport-coupled phosphorylation C 5 2 Pyruvate C 6 Oxalacetate 2 Citrate 3 Aconitate 3 Malate 2 Isocitrate 3 Fumarate 2 Succinate 2 Succinyl-CoA -Ketoglutarate 2 Electron transportcoupled phosphorylation Fig. 4.14

4 Aerobic Respiration E 0 (V) Electron transport process in the membrane of Paracoccus denitrificans 0.22 Complex I (NADH:quinone oxidoreductase) NADH donates e - to FMN FMN donates e - to quinone Complex II (succinate dehydrogenase complex) Bypasses Complex I Feeds e - and H + from FADH directly to quinone pool ENVIRONMENT Q cycle Complex II Succinate Fumarate CYTOPLASM Complex III (cytochrome bc 1 complex) Transfers e - from quinones to cytochrome c Cytochrome c shuttles e - to cytochromes a and a Complex IV (cytochromes a and a 3 ) Terminal oxidase; reduces O 2 to H 2 O 0.39 E 0 (V) Chap Fig. 4.19

5 Aerobic Respiration Electron transport process in the membrane of Escherichia coli Chap Fig a

6 Anaerobic Respiration The use of electron acceptors other than oxygen Examples include nitrate (NO 3- ), ferric iron (Fe 3+ ), sulfate (SO 4 2- ), carbonate (CO 3 2- ), certain organic compounds Less energy released compared to aerobic respiration Energy released from redox reactions can be determined by comparing reduction potentials of each electron acceptor Dependent on electron transport, generation of a proton motive force, and ATPase activity Chap. 4.12, 14.6

Major Forms of Anaerobic Respiration 0.42 0.3 Anoxic Proton reduction; Pyrococcus furiosus, obligate anaerobe Carbonate respiration; acetogenic bacteria, obligate anaerobes 0.27 0.

7 Major Forms of Anaerobic Respiration Anoxic Proton reduction; Pyrococcus furiosus, obligate anaerobe Carbonate respiration; acetogenic bacteria, obligate anaerobes Sulfur respiration; facultative aerobes and obligate anaerobes Carbonate respiration; methanogenic Archaea; obligate anaerobes 0.22 E 0 (V) 0 Sulfate respiration (sulfate reduction); obligate anaerobes (SO 4 2- SO 3 2-, E ) Fumarate respiration; facultative aerobes 0.2 Iron respiration; facultative aerobes and obligate anaerobes Thermodynamic hierarchy of electron acceptors Oxic (oxygen present) Reductive dechlorination; facultative aerobes and obligate anaerobes Nitrate respiration; facultative aerobes (some reduce NO 3- to NH 4 ) Denitrification; facultative aerobes Manganese reduction; facultative aerobes Aerobic respiration; obligate and facultative aerobes Organisms: Enterobacteria, e.g. E. coli Organisms: (many) Pseudomonas Paracoccus Chap Fig

reductase Denitrification (Pseudomonas stutzeri) Gases Nitrous oxide N 2 O Nitrous oxide

8 Dissimilative Reduction of Nitrate Nitrate Nitrite NO 3 Nitrate reductase NO 2 Nitrate reduction (Escherichia coli) NH 4 + Nitrite reductase Nitric oxide NO Nitric oxide reductase Denitrification (Pseudomonas stutzeri) Gases Nitrous oxide N 2 O Nitrous oxide reductase Dinitrogen N 2 -> Denitrification is a biological source of gaseous N 2 Chap Fig

Respiration and Anaerobic Respiration Periplasm Periplasm Nitrate reductase complex Q cycle Q cycle Nitrate reductase Cytoplasm Cytoplasm Aerobic respiration Nitrate

9 Respiration and Anaerobic Respiration Periplasm Periplasm Nitrate reductase complex Q cycle Q cycle Nitrate reductase Cytoplasm Cytoplasm Aerobic respiration Nitrate reduction Periplasm Nitrate reductase complex NO 2 reductase N 2 O reductase Q cycle Nitrate reductase Nitric oxide reductase Cytoplasm Denitrification Chap Fig

10 Major Forms of Anaerobic Respiration Anoxic Proton reduction; Pyrococcus furiosus, obligate anaerobe Carbonate respiration; acetogenic bacteria, obligate anaerobes Sulfur respiration; facultative aerobes and obligate anaerobes Carbonate respiration; methanogenic Archaea; obligate anaerobes 0.22 E 0 (V) 0 Sulfate respiration (sulfate reduction); obligate anaerobes (SO 4 2- SO 3 2-, E ) Fumarate respiration; facultative aerobes Iron respiration; facultative aerobes and obligate anaerobes Reductive dechlorination; facultative aerobes and obligate anaerobes Nitrate respiration; facultative aerobes (some reduce NO 3- to NH 4 ) Organisms: Shewanella Geobacter 0.75 Denitrification; facultative aerobes Manganese reduction; facultative aerobes 0.82 Oxic (oxygen present) Aerobic respiration; obligate and facultative aerobes Chap Fig

11 Microbial Fuel Cell

12 Electricigens Potential mechanisms for electron transfer

13 Major Forms of Anaerobic Respiration Anoxic Proton reduction; Pyrococcus furiosus, obligate anaerobe Carbonate respiration; acetogenic bacteria, obligate anaerobes E 0 (V) 0 Sulfur respiration; facultative aerobes and obligate anaerobes Carbonate respiration; methanogenic Archaea; obligate anaerobes Sulfate respiration (sulfate reduction); obligate anaerobes (SO 4 2- SO 3 2-, E ) Fumarate respiration; facultative aerobes Organisms: Methanosarcina Methanobacterium Methanococcus Methanopyrus Iron respiration; facultative aerobes and obligate anaerobes Reductive dechlorination; facultative aerobes and obligate anaerobes 0.4 Nitrate respiration; facultative aerobes (some reduce NO 3- to NH 4 ) 0.75 Denitrification; facultative aerobes 0.82 Oxic (oxygen present) Manganese reduction; facultative aerobes Aerobic respiration; obligate and facultative aerobes Chap Fig

14 Methanogenesis and Acetogenesis Methanogenesis ( G kj) Proton or sodium motive force (plus substrate-level phosphorylation for acetogens) Acetogenesis ( G kj) at 1-10 Pa H 2 : G = - 17 kj/mol) Some methanogens also use acetate or methanol as substrate Chap Fig

15 Methanogenesis Methanogenesis is the only way that methanogenic archaea can obtain energy for growth. => Specialization Methanogens are the only organisms known to produce methane (CH 4 ) as a catabolic end product. They are strict anaerobes. Atmospheric concentrations of methane have doubled since 200 years.

16 Anoxic Decomposition

17 Rumen and Gastrointestinal System of a Cow The rumen contains microbes/g of rumen constituents Microbial fermentation in the rumen is mediated by celluloytic microbes that hydrolyze cellulose to free glucose that is then fermented, producing volatile fatty acids (e.g., acetic, propionic, butyric) and the CH 4 and CO 2 Fatty acids pass through rumen wall into bloodstream and are utilized by the animal as its main energy source Chap Fig

18 Biochemical Reactions in the Rumen Rumen microbes also synthesize amino acids and vitamins for their animal host Rumen microbes themselves can serve as a source of protein to their host when they are directly digested Chap Fig

19 Rumen and Gastrointestinal System of a Cow The rumen contains microbes/g of rumen constituents Microbial fermentation in the rumen is mediated by celluloytic microbes that hydrolyze cellulose to free glucose that is then fermented, producing volatile fatty acids (e.g., acetic, propionic, butyric) and the CH 4 and CO 2 Fatty acids pass through rumen wall into bloodstream and are utilized by the animal as its main energy source Chap Fig

20 Biochemical Reactions in the Rumen Rumen microbes also synthesize amino acids and vitamins for their animal host FEED, HAY, etc. Cellulose, starch, sugars Cellulolysis, amylolysis Fermentation Fermentation SUGARS Formate Rumen microbes themselves can serve as a source of protein to their host when they are directly digested Pyruvate Succinate Lactate Propionate CO 2 Ruminant bloodstream Acetate Propionate Rumen wall Butyrate VFAs Acetate Removed by eructation to atmosphere Overall stoichiometry of rumen fermentation: Chap Fig

21 1) Nutrients and microbial growth 2) Introduction to principles of metabolism 3) Chemoorganotrophy 4) Chemolithotrophy 5) Phototrophy 6) Autotrophy, nitrogen fixation 7) Global carbon, nitrogen, sulfur cycles Brock Biology of Microorganisms, Twelfth Edition Madigan / Martinko / Dunlap / Clark

22 Chemolithotrophy: Beggiatoa

23 Sergej Winogradsky: Concept of Chemolithotrophy 1887 Sulfur oxidizers Drawings made by Winogradsky of Beggiatoa. Fig. 1. The tip of a filament of Beggiatoa alba: (a) in sulfurous [sulfidecontaining] water, (b) after 24 h in water nearly depleted in H 2 S, (c) after 48 h in water without H2S. Fig. 2. The tip of a filament of Beggiatoa media. Fig. 3. The tip of a filament of Beggiatoa minima. From Winogradsky, S Microbiologie du Sol. Masson, Paris. Fig. 1.2

24 Chemolithotrophy Chemolithotrophs are organisms that obtain energy from the oxidation of inorganic compounds Most chemolithotrophs obtain their carbon from CO 2 (autotrophs) Many sources of reduced molecules exist in the environment The oxidation of different reduced compounds yields varying amounts of energy Chap. 13.6

25 Chemolithotrophic processes Chap. 13.6

26 Energy Yields from Oxidation of Inorganic Electron Donors Chap. 13.6

27 Hydrogen Oxidizers (aerobic) / Knallgas bacteria > Large amounts of hydrogen are formed during the anaerobic biological degradation of organic material. > Low amounts are also released during geochemical processes and are found in vulcanic gases. H O 2 -> H 2 O ( G = kj/mol) Key enzyme: Hydrogenase (Fe, S) (Ni, Fe) Knallgasbakterien aerobic hydrogen oxidizing microorganisms: Ralstonia eutropha (Alcaligenes), Paracoccus (usually facultative chemolithotroph) Chap. 13.7

28 Hydrogenases of Aerobic Hydrogen oxidizing Bacteria Membrane-integrated hydrogenase Out In Cytoplasmic hydrogenase Cell material Chap Fig

Nitrification NH 3 and NO 2 - are oxidized by nitrifying bacteria (and archaea) during the process of nitrification Ammonium-oxidizing Two groups of

They can be found in nature wherever ammonium is liberated and oxygen is available.

29 Nitrification NH 3 and NO 2 - are oxidized by nitrifying bacteria (and archaea) during the process of nitrification Ammonium-oxidizing Two groups of bacteria work in concert to fully oxidize ammonia to nitrate The nitrifiers are widespread in soil and water. They can be found in nature wherever ammonium is liberated and oxygen is available. Like many other chemolithotrophs, the nitrifiers are particularly active at the oxic/anoxic interface of sediments and water bodies. Nitrite-oxidizing Only small energy yields from this reaction => Growth of nitrifying bacteria is very slow Chap

30 Oxidation of Ammonia by Ammonia-Oxidizing Bacteria AMO, ammonia monooxygenase Oxidation of hydroxylamine Out HAO, hydroxylamine oxidoreductase Cyt aa3, terminal cyt c oxidase (complex IV) In Oxidation of ammonia Reduction of oxygen Chap Fig

31 Oxidation of Nitrite to Nitrate by Nitrifying Bacteria NXR, nitrite oxidoreductase Periplasm Cyt aa3, terminal cyt c oxidase (complex IV) Reverse e flow to make NADH Cytoplasm Oxidation of nitrite Reduction of oxygen Chap Fig

32 Degradation of limestone Agriculture NH 3 NO 2 - NO 3 - salpetrige Säure Nitrous acid Salpetersäure Nitric acid Ca(CO 3 ) 2

33 Nitrifiers in waste-water treatment The chemolithoautotrophic ammonium- and nitrite-oxidizing bacteria play a vital role in modern waste-water treatment for nitrogen removal.

Anammox Anammox: anoxic ammonia oxidation (to N 2 gas) NH 4 + + NO 2 - -> N

(Plantomycetes) Anammoxosome is compartment where anammox reactions occur

) is an intermediate of anammox Anammox is very beneficial in the treatment

34 Anammox Anammox: anoxic ammonia oxidation (to N 2 gas) NH NO 2 - -> N 2 + H 2 O Performed by unusual group of obligate aerobic bacteria (Plantomycetes) Anammoxosome is compartment where anammox reactions occur Protects cell from reactions occuring during anammox Hydrazine (H 2 N-NH 2 ) is an intermediate of anammox Anammox is very beneficial in the treatment of wastewater Anammoxosome membrane Electron transport Out In Chap Fig

Julia Vorholt Lecture 7:

752-4001-00L Mikrobiologie Julia Vorholt Lecture 7: Chemoorganotrophy Nov 5, 2012 Brock Biology of Microorganisms, Twelfth Edition Madigan / Martinko / Dunlap / Clark Copyright 2009 Pearson Education Inc.,