1. The Bacteria Phylogenetic tree of the major lineages of Bacteria based on 16S ribosomal RNA Sequence comparisons

2. The Purple Bacteria, also called Proteobacteria is the largest and most physiological diverse of all bacteria

3. Bacteria §Purple and Green (Anoxygenic Phototrophic Bacteria)Purple and Green (Anoxygenic Phototrophic Bacteria) §Cyanobacteria （藻青菌）Cyanobacteria §ProchlorophytesProchlorophytes §Chemolithotrophs: Nitrifying BacteriaChemolithotrophs: Nitrifying Bacteria §Chemolithotrophs: Sulfur- and Iron-Oxidizing BacteriaChemolithotrophs: Sulfur- and Iron-Oxidizing Bacteria §Chemolithotrophs: Hydrogen-Oxidizing BacteriaChemolithotrophs: Hydrogen-Oxidizing Bacteria §Methanotrophs and MethylotrophsMethanotrophs and Methylotrophs §Sulfate and Sulfur-Reducing Bacteria §Homoacetogenic Bacteria §Budding and Appendaged (Prosthecate) Bacteria §Spirilla §Spirochetes §Gliding Bacteria §Sheathed Bacteria

4. Purple and Green (Anoxygenic Phototrophic) Bacteria §Purple Bacteria: l Bacteriochlorophylls a, b （细菌叶绿素） l Anoxygenic photosynthesis l One photosystem §Green Bacteria: l Bacteriochlorophylls c, d or e l Anoxygenic photosynthesis l One photosystem §Cyanobacteria: l Bacteriochlorophyll a l Oxygenic photosynthesis l Two photosystems

5. Purple and Green (Anoxygenic Phototrophic) Bacteria Bacteriochlorophylls §Bacteriochlorophylls differ in substituents on various parts of the porphyrin ring; §The various modifications lead to changes in the absorption spectra of the bacteriochlorophylls; §From the long-wavelength maximum, the identification of the bacteriochlorophyll can be made.

6. Purple and Green (Anoxygenic Phototrophic) Bacteria Classification §Anoxygenic phototrophic bacteria are classified based on their bacteriochlorophylls and photosynthetic membrane systems into three major groups: l Purple Bacteria (Nonsulfur purple, Purple sulfur bacteria) l Green Bacteria (Green sulfur, green nonfulfur bacteria) l Heliobacteria §Anoxygenic phototrophic bacteria also produce carotenoid （类胡罗卜素） pigments. Therefore, the colors of the bacteria are the combination of bacterio-chlorophylls and carotenoid pigments

7. Purple and Green (Anoxygenic Phototrophic) Bacteria Classification

8. Purple and Green (Anoxygenic Phototrophic) Bacteria Carotenoids Carotenoid-less mutant, the actual Bchl a color Carotenoid-less mutant

9. Purple and Green (Anoxygenic Phototrophic) Bacteria Photosynthetic Membrane Systems Differences between green and purple bacteria in the Photosynthetic Membrane Systems In purple bacteria: photosynthetic pigments are parts of the internal membane (lamellae 薄层 ). In green bacteria: photosynthetic apparatus consists of a series of cylindrically shaped structures called chloroforms underlaying and attached to the cytoplasmic membrane. In heliobacteria: bacteriochlorophyll is associated with the cytoplasmic membrane Purple bacteria Green Bacteria Heliobacteria

10. Purple and Green (Anoxygenic Phototrophic) Bacteria Nonsulfur purple bacteria §can only used sulfide at a low concentration; §have great photoheterotrophic abilities; §some have ability to utilize methanol as sole carbon source for phototrophic growth; §most are active N 2 fixers. Rhodospirilum fulvum Rhodopseudomonas acidophila Rhodobacter sphaeroides Rhodopila globiformis Rhodocyclus purpureus Rhodomicrobium vannielii

11. Purple and Green (Anoxygenic Phototrophic) Bacteria Purple sulfur bacteria §deposit sulfur and oxidize it to sulfate, §commonly found in anoxic zones of lakes as well as in sulfur springs, §Ectothiorhodospira deposits sulfur externally, grows halophilically and at high pH, found in saline lakes, saltern, and bodies of water high in salt, §limited ability to utilize organic compounds as C source for phototrophic growth §Thiocapsa grows chemoorganotrophically on acetate

12. Purple and Green (Anoxygenic Phototrophic) Bacteria Purple sulfur bacteria Chromatium okenii Thiospirillum jenense ThiocapsaThiopedia rosea

13. Purple and Green (Anoxygenic Phototrophic) Bacteria Green sulfur bacteria §Morphologically diverse (nonmotile rods, spirals, spheres, motile filamentous gliding, prosthecae); §Some living planktonically in lakes possess gas vesicles; §Strictly anaerobic; §Obligate phototrophic; §Most can assimilate simple organic substances (acetate, propionate, pyruvate and lactate)for phototrophic growth provided that a reduced sulfur compound is present as a sulfur source; Chlorobium limicola Pelodictyron clathratiforme

14. Purple and Green (Anoxygenic Phototrophic) Bacteria Green nonsulfur bacteria §Chloroflexus has been given the designation green nonsulfur bacterium; §able to grow chemoorganotrophically in the dark under aerobic conditions; §able to grow phototrophically on a wide variety of sugars, amino acids, and organic acids; §able to grow phototrophically with H 2 S or H 2 and CO 2 ; §best grow photoheterotrophically; Chloroflexus aurantiacus Oscillochloris

15. Purple and Green (Anoxygenic Phototrophic) Bacteria Heliobacteria §Phylogenetically separate group of anoxygenic phototrophic bacteria that contain bacteriochlorophyll g; §Consisting of l Heliobacterium l Heliophilum l Heliobacillus §Strictly anaerobic phototrophs; §Unable to grow by respiratory means; §Similarity between Bchl g and Chlorophyll a (modified form of hydroxychlorophyll a); Heliobacillus mobilis

16. Purple and Green (Anoxygenic Phototrophic) Bacteria A Comparison of electron flow in green sulfur, heliobacteria and purple bacteria Bchl a Bchl g

17. Purple and Green (Anoxygenic Phototrophic) Bacteria Ecology Purple sulfur bacteria from a stratified lake Green sulfur bacteria from a stratified lake

18. Purple and Green (Anoxygenic Phototrophic) Bacteria Ecology Vertical stratification of purple sulfur bacteria (Amoebabacter purpureus in a CanadianLake A syringe sampling device that can collect water at intervals The phototrophic bacterium forms a layer just at the top of the anoxic zone Membrane filters through which were passed water samples taken at varying depth

19. Purple and Green (Anoxygenic Phototrophic) Bacteria Ecology Massive accumulation of purple sulfur bacteria: Thiopedia roseopersicinia in a spring in Madison. The green color is from cells of alga Spirogyra Cross-section through a bacterial mat: top: cyanobacteria; pink: phototrophic purple sulfur bacteria black: sulfate-reducing bacteria peach: Bchl b containing cells of Thiocapsa

21. Cyanobacteria: Diversity §A large and heterogeneous group of phototrophic bacteria §Oxygenic phototrophs, Bergey’s Manual has divided them into 5 major groups §Contain unsaturated fatty acids with two or more double bonds instead of one in other bacteria. Unicellular Gloeothece Colonial Dermocarpa Filamentous, Oscillatoria Filamentous heterocystous Anabaena Filamentous branching Fischerella Similar to gram-positive bacteria. All cyanobacteria have chlorophyll a All have biliprotein （胆蛋白质） pigments: Phycobilins （藻胆素）, or Phycoerythrin （藻红蛋白）

22. Cyanobacteria Structural variations: gas vesicles and heterocysts §Gas vesicles: provide flotation, so the cells will remain where there is most light. §Heterocysts: rounded, distributed regularly along a filament or at one end of a filament, are the sole sites of nitrogen fixation in heterocystous cyanobacteria Heterocysts in cyanobacterium Anabaena

24. Prochlorophytes §Prokaryotic oxygenic phototrophs that contain chlorophyll a and b but do not have phycobilins. §Resemble both cyanobacteria and the plant chloroplast. The first prochlorophyte discovered is Prochloron, has extensive thylakoid membrane system similar to chloroplast Filamentous prochlorophyte Prochlorothrix Prochlorophytes, cyanobacteria and the plant chloroplasts share a common ancestor

25. Chemolithotrophs: Nitrifying Bacteria §Bacteria able to grow chemolithotrophically at the expense of reduced inorganic nitrogen compounds l (1) Nitrosifying bacteria: l NH 3 + O 2 NO 2 - + H + + H 2 O l (2) Nitrifying bacteria: l NO 2 - + O 2 NO 3 - §No chemolithotroph is known that will carry out the complete oxidation of ammonia to nitrate §(1) Nitrosomonas, Nitrosococcus, Nitrosospira §(2) Nitrobacter, Nitrospira, Nitrococcus §They are members of the purple bacteria

26. Chemolithotrophs: Sulfur- and Iron-Oxidizing Bacteria §Members of purple bacteria §Have ability to grow chemolithotrophically on reduced sulfur compounds §Only six genera: Thiobacillus, Thiosphaera, Thiomicrospira, Thermothrix, Beggiatoa and Sulfolobus (Archaea) have been cultured. §Two groups: neutrophilic and acidophilic §The acidophilic group can grow chemolithotrophically using ferrous iron as electron donor §Thiobacillus ferrooxidans has been used for leaching

27. Chemolithotrophs: Hydrogen-Oxidizing Bacteria §Capable of growing with H2 as sole electron donor and O2 as electron acceptor, §Many of them can also grow autotrophically using Calvin cycle to fix CO2, §All contain hydrogenase for binding H2 and use it to produce ATP, §Can grow both chemoorganotrophs and chemolithotrophs, §Most are obligate aerobes, but prefer microaerobic conditions when growing chemolithotrophically on H 2, §Some can grow on CO, §Best studied Alcaligenes eutrophus, or Ralstonia eutropha

28. Methanotrophs and Methylotrophs §Methanotrophs: l utilize methane, and/or a few other one-carbon compounds as sole source of carbon l aerobes (Purple Bacteria) l widespread in nature in soil and water l possess methane monooxygenase l obligate C1 utilizers l contain large amount of sterols in internal membrane §Methylotrophs: l utilize methane and other one-carbon compounds as electron donors for energy generation and as sole sources of carbon l many can utilize organic acids, ethanols and sugars

29. Methanotrophs and Methylotrophs Classification §Based on internal cell structure and carbon assimilation pathway: l Type I: ribulose monophosphate cycle, lack a complete TCA cycle l Type II: Serine pathway Methylosinus, Type II Methylococcus capsulatus, Type I

30. Methanotrophic Symbionts of Animals §Intact mussels as well as isolated mussel gill tissue consume methane at high rates in the presence of O 2 due to symbiotic methanotrophic bacteria presence. Symbiotic methanotrophs in the gill tissue of a marine mussel living near hydrocarbon seeps in the Gulf of Mexico