1. Metabolic Diversity Every living being needs: –Energy source (inorganic,organic, light) –Carbon source (inorganic or organic)

3. Phototrophy Microbial phototrophs: –Anoxygenic Purple (non)-sulfur bacteria (proteobacteria) Green sulfurs Green non-sulfurs –Oxygenic Cyanobacteria Prochlorophytes

6. Photosynthetic Pigments Chlorophylls –Porphyrins (like cytochromes) with Mg + –Bacteriochlorophylls a, b, c, d, e, g Phycobilins (phycoerythrin, phycocyanin) Carotenoids –Hydrophobic –Hydrocarbon chains with conjugated bonds

10. Light reaction: –Light energy is conserved as chemical energy Dark reaction: –Chemical energy is used to reduce CO 2 to organic compounds Reaction center Light harvesting (antenna)

12. Photosynthetic complex in PSB

14. Oxygenic Photosynthesis Involves two distinct photochemical reactions (photosystems I(P700) and II(P680)) Use light to generate both ATP and NADPH Electron transfer in photosystem I produces H + gradient (also cyclic photophosphorylation)

15. CO 2 Fixation Calvin cycle requires NAD(P)H and ATP Ribulose biphosphate carboxylase (RubisCO) Stoichiometry: –6 CO 2 + 12 NADPH + 18 ATP  C 6 H 12 O 6 (PO 3 H 2 ) + 12 NADP+ + 18 ADP +17 P i Carboxysomes –Polyhedral cell inclusions with crystalline arrays of RubisCO

17. Reverse Citric Acid Cycle Green sulfur bacteria and green non-sulfur bacteria Archaea Sulfolobus and Thermoproteus Ferredoxin linked enzymes

18. Hydroxypropionate Cycle Chloroflexus (green non-sulfur) 2 CO 2 are reduced to glyoxylate key intermediate is hydroxypropionate

19. Chemolithotrophy Obtain energy from the oxidation of inorganic compounds ATP synthesis is coupled to oxidation of electron donor Possible electron donors: H 2, sulfide, S 0, ammonium, NO 2 -, Fe 2+

20. H 2 -oxidation catalyzed by hydrogenase, soluble or membrane-bound; most H 2 - oxidizer are also capable of chemoheterotrophic growth Oxidation of reduced Sulfur compounds (H 2 S, S 0, S 2 O 3 - ) via SO 3 2- Iron oxidation (Fe 2+ to Fe 3+ ), anaerobic ferrous iron oxidation by anoxygenic phototrophs (banded iron formation)

23. Nitrification Nitrogen compounds as e - -donors: NH 3 and NO 2 - Nitrifiers in soil and water Ammonia monooxygenase Anammox

25. Anaerobic Respiration Terminal e - -acceptors others than O 2 : Fe 3+, NO 3 -, fumarate, SO 4 2-, CO 2, S 0 Yields less energy than the oxidation of the same compound with O 2 would Dissimilative metabolism