Lecture 4: Metabolic Diversity

Aerobes

Require oxygen for growth

Anaerobes

Oxygen is not required for growth

Facultative aerobe

Oxygen is not required but enhances growth rate

Chemooranotrophs

Chemicals for energy and electrons from organic compounds (glucose)

Chemolithotrophs

Chemicals as energy source, inorganic compounds for electron source and carbon

Phototrophs

Light as energy source and used for ATP production

Heterotroph

Carbon is acquired from organic chemicals

Autotroph

Carbon acquired from carbon dioxide

Chemoheterotroph

Glucose used for ATP production and glucose turns into cell material

Denitrifying bacteria

Organic compounds source of carbon, energy and electrons, nitrogen compounds as terminal electron acceptor in anaerobic conditions

Sulfate and sulfur reduction (desulfovibrio/desulfuromonas)

Organic compounds source of carbon, energy and electrons sulfur compounds as terminal electron acceptor

Adsorption of light energy

Light sensitive pigments and photo complexes harvest light energy

Reaction center

Chlorophyll or bacteria chlorophyll arrange into complexes with accessory pigments and harvest light energy

Carotenoids

Hydrophobic light sensitive pigments in photosynthetic membrane and they protect the system from bright light

Phycobilins

Form complexes with proteins that are main harvesting systems in Cyanobacteria

Site of photosynthesis Eukaryotes

Chloroplast in plants and algae have chlorophyll’s attached to thylakoid membrane pmf generated across membrane

Sites of photosynthesis bacteria

Pigments integrated into internal membranes

Heliobacteria photosynthesis location

Photosynthetic pigments in cytoplasmic membrane

Purple bacteria photosynthesis location

Photosynthetic pigments in intracytoplasmic membrane systems, vesicles and lamellae

Cyanobacteria and prochlorophytes photosynthesis location

Thylakoid membrane

Chlorosome in green sulfer and green nonsulfer

Giant antenna systems arranged in arrays in chlorosome and transfer energy to reaction center, catches very low intensity light

Anoxygenic photosynthesis: purple sulfur bacteria

H2S reduces NAD+, p870 not enough reducing power so produces NADH with reverse electron flow, has low yield

Anoxygenic photosynthesis: purple non sulfur bacteria

Succinate reduces NAD+

Anoxygenic photosynthesis: green sulfur bacteria

Cyclic photophosphorylation, no electron donor, electrons cycle. PFM makes ATP and reduced NAD+ oxidizes H2S

Oxygenic photosynthesis

Algae and Cyanobacteria use light energy to oxidize H2O creates PFM driving ATP synthesis

Chemoautotrophs

Primary producers, nitrifying bacteria, sulfer bacteria, use inorganic compounds as sources of energy and electrons use CO2 as carbon source

Nitrifying Bacteria

Inorganic nitrogen compounds as electron donors, only in aerobic conditions

Nitrosomonas spp.

O2 final electron acceptor, ammonia monooxygenase needs 2 electrons to oxidize ammoniaNADH produced by reverse electron flow

Nitrobacter spp.

Final electron acceptor O2, nitrite oxide reductive, NADH by reverse electron flow, low yield

Thiobacillus spp.

Sulfur bacteria, oxidize sulfer compounds use O2 as final acceptor, produce SO4 and protons, NADH by reverse electron flow

Methanogens

Produce CH4, strict anaerobes found in marshes and anaerobic sediments

Methanotrophs

Aerobes use CH4 as carbon and energy source

Calvin cycle

Fixes CO2, produces C6H12O6 (PO3H2) + 12NADP+ +18 ADP +17 pi