MICROBIOLOGIA GENERALE Microbial metabolisms 2

aerobic respiration in chemolithotrophs Microbial metabolism aerobic respiration in chemolithotrophs

H20, H2S, S, organic molecules Metabolism e- donor e- acceptor Microorganisms Fermentation Organic molecules Organic molecule Obligately anaerobic and facultative chemoorganotrophic Aerobic Respiration Organic molecules Inorganic O2 Obligately aerobic and facultative Chemolithotrophs Anaerobic Respiration Organic or inorganic molecules NO3 SO4 CO2 Nitrate reducers Sulfate reducers Methanogenic Photosynthesis H20, H2S, S, organic molecules NADP NADPH Cyanobacteria, Green and Purple bacteria

Energetics and carbon flow in chemolithotrophic respiratory metabolism

Energetics and carbon flow in chemolithotrophic respiratory metabolism

Type of chemolithotrophs Energy yields from the oxidation of various inorganic electron donor Electron donor Reaction Type of chemolithotrophs E0’ of couple (V) Hydrogen H2+1/2O2 H2O Hydrogen bacteria -0.42 Sulfide HS-+H++1/2O2 S0+H20 Sulfur bacteria -0.27 Sulfur S0+1/2O2+H2O SO42-+H2O -0.20 Ammonium NH4++1/2O2 NO2 +2H+ +H2O Nyitrifyng bacteria +0.34 Nitrite NO2-+1/2O2 NO3- Nitrifying bacteria +0.43 Ferrous ion Fe2++H++1/4O2 Fe3+ +1/2O2 Iron bacteria +0.77

Bioenergetics and function of two hydrogenases of an aerobic H2 bacterium: Ralstonia eutropha

Bioenergetics and function of two hydrogenases of an aerobic H2 bacterium: Ralstonia eutropha

Oxidation of ammonia and electron flow in ammonia-oxidizing bacteria: the nytrosofyer Nitrosomonas

Oxidation of nitrite to nitrate by the nytrifyng Nitrobacter

NAD+/NADH+H+ = -0.32V NO2-/NH3 = +0.34V NO2-/NO3- = +0.43V Reverse electron flow

Steps in the oxidation of reduced sulfur compounds by sulfur chemolithotrophs Deposition of internal sulfur granules by Beggiatoa

Oxidation of reduced sulfur compounds by sulfur chemolithotrophs

Electron flow during Fe2+ oxidation by the acidophile Thiobacillus ferrooxidans

Reverse electron flow Energetics and electron flow during Fe2+ oxidation by the acidophile Acidithiobacillus ferrooxidans

Model for anaerobic ammonium oxidation coupled to the anammoxosome membrane in anammox bacteria

anaerobic respiration Microbial metabolism anaerobic respiration

H20, H2S, S, organic molecules Metabolism e- donor e- acceptor Microorganisms Fermentation Organic molecules Organic molecule Obligately anaerobic and facultative chemoorganotrophic Aerobic Respiration Organic molecules Inorganic O2 Obligately aerobic and facultative Chemolithotrophs Anaerobic Respiration Organic or inorganic molecules NO3 SO4 CO2 Nitrate reducers Sulfate reducers Methanogenic Photosynthesis H20, H2S, S, organic molecules NADP NADPH Cyanobacteria, Green and Purple bacteria

The anaerobic way of life: examples of anaerobic respirations

Anaerobic respiration 1. Nitrate reduction and the denitrification: facultative aerobes (Escherichia, Pseudomonas) 2. Sulfate reduction: obligate anaerobes (Desulfovibrio) 3. Carbonate respiration (methanogenesis): Archaea obligate anaerobes (Methanobacterium) 4. Carbonate respiration (acetogenesis): homoacetogenic bacteria obligate anaerobes (Acetobacterium) 5. Ferric iron, manganese, fumarate, halogenated compounds:facultative aerobes and obligate anaerobes

Steps in the dissimilative reduction of nitrate

Electron transport in Pseudomonas stutzeri during denitrification

Electron transport in E. coli when O2 or NO3- is the electron acceptor

Electron transport in sulfate-reducing bacteria

Electron transport in sulfate-reducing bacteria

Hydrogen is a major electron donor for homoacetogens and methanogens that can use CO2 as electron acceptor

Microbial metabolism photosynthesis

H20, H2S, S, organic molecules Metabolism e- donor e- acceptor Microorganisms Fermentation Organic molecules Organic molecule Obligately anaerobic and facultative chemoorganotrophic Aerobic Respiration Organic molecules Inorganic O2 Obligately aerobic and facultative chemoorganotrophic Chemolithotrophs Anaerobic Respiration Organic or inorganic molecules NO3 SO4 CO2 Nitrate reducers Sulfate reducers Methanogenic Photosynthesis H20, H2S, S, organic molecules NADP NADPH Cyanobacteria, Green and Purple bacteria

Energetics and carbon flow in phototrophic metabolism

Energetics and carbon flow in phototrophic metabolism

Classification of phototrophic organisms in terms of energy and carbon sources.

Oxygenic photosynthesis green plants, algae and cyanobacteria e-and H+ donor: H2O nH2O+nCO2 (CH2O)n + nO2 Light Anoxygenic photosynthesis purple and green bacteria, heliobacteria e-and H+ donor: H2S, S2O32-, H2, organic compounds 2H2S+CO2 (CH2O) +H2O +2S Light

Energy and reducing power synthesis in oxygenic phototrophs. Oxygenic phototrophs obtain their energy from light (hv) and light also drives the oxidation of water to oxygen.

Energy and reducing power synthesis in anoxygenic phototrophs Anoxygenic phototrophs obtain their energy from light (hv).

Structures of chlorophyll a

Structures of bacteriochlorophyll a

Structure of all known bacteriochlorophylls

The chlorosome of green sulfur and green nonsulfur bacteria

Model for the arrangement of light-harvesting chlorophylls/bacteriochlorophylls versus reaction centers

Structure of b-carotene, a typical carotenoid

Structure of a ficobilosome

Reaction center (RCII) in the anoxygenic photosynthesis of a purple bacterium

Cyclic Photophosphorylation General scheme of electron flow in anoxygenic photosynthesis in a purple bacterium

Arrangement of protein complexes in the photosynthetic membrane of a purple phototrophic bacterium

Arrangement of protein complexes in the photosynthetic membrane of a purple phototrophic bacterium

General scheme of electron flow in anoxygenic photosynthesis in a purple bacterium NAD(P)H Generation

A comparison of electron flow in purple bacteria, green sulfur bacteria, and heliobacteria

A comparison of electron flow in purple bacteria, green sulfur bacteria, and heliobacteria

Electron flow in oxygenic photosynthesis, the “Z” scheme

Electron flow in oxygenic photosynthesis, the “Z” scheme

Key enzyme reaction of the Calvin cycle. Reaction of the enzyme ribulose bisphosphate carboxylase.

Key enzyme reaction of the Calvin cycle. Steps in the conversion of 3-phosphoglyceric acid (PGA) to glyceraldehyde 3-phosphate.

Key enzyme reaction of the Calvin cycle. Conversion of ribulose 5-phosphate to the acceptor molecule ribulose bisphosphate by the enzyme phosphoribulokinase.

The Calvin cycle: For each six molecules of CO2 incorporated, one fructose 6-phosphate is produced

Amino acid biosynthesis

Map of the photosynthetic gene cluster of the purple phototrophic bacterium, Rhodobacter capsulatus

Ammonia incorporation in bacteria