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Figure 17.1 Deferribacter Cytophaga Flavobacteria Spirochetes Planctomyces/ Pirellula Verrucomicrobiaceae Green sulfur bacteria Deinococci Green nonsulfur bacteria Chlamydia Cyanobacteria Thermotoga Actinobacteria Firmicutes and Mollicutes Gram-positive bacteria Thermodesulfobacterium Nitrospira Aquifex © 2012 Pearson Education, Inc. See Figure 17.2 Proteobacteria 17.1 Phylogenetic Overview of Bacteria • Proteobacteria (Figure 17.2) – A major lineage (phyla) of Bacteria – Includes many of the most commonly encountered bacteria – Most metabolically diverse of all Bacteria • Chemolithotrophy, chemoorganotrophy, phototrophy – Morphologically diverse – Divided into five classes • Alpha-, Beta-, Delta-, Gamma-, Epsilon- © 2012 Pearson Education, Inc. Figure 17.2 16S rRNA Gene Tree of Proteobacteria Proteobacterial Classes Bacillus Nitrosococcus Thermochromatium Acidithiobacillus Beggiatoa Gamma Pseudomonas Vibrio Escherichia Methylobacter Gallionella Nitrosomonas Methylophilus Derxia Beta Ralstonia Spirillum Rhodocyclus Thiobacillus Neisseria Methylobacterium Nitrobacter Rhodopseudomonas Beijerinckia Alpha Paracoccus Azotobacter Rickettsia Acetobacter Zeta Mariprofundus Campylobacter Sulfurimonas Epsilon Thiovulum Wolinella Desulfosarcina Desulfovibrio Delta Myxococcus Nitrospina Major metabolisms © 2012 Pearson Education, Inc. Chemolithotrophy Anoxygenic phototrophy Methylotrophy Sulfur compounds (H2S, S0, etc.) Ferrous iron (Fe2) Sulfate reduction Nitrogen fixation Ammonia (NH3) or nitrite (NO2) Hydrogen (H2) 17.2 Purple Phototrophic Bacteria • Purple phototrophic bacteria – Carry out anoxygenic photosynthesis; no O2 evolved – Contain bacteriochlorophylls and carotenoid pigments (Figure 17.3) – Produce intracytoplasmic photosynthetic membranes with varying morphologies © 2012 Pearson Education, Inc. Figure 17.3 © 2012 Pearson Education, Inc. Figure 17.4 © 2012 Pearson Education, Inc. 17.2 Purple Phototrophic Bacteria • Purple sulfur bacteria – Use hydrogen sulfide (H2S) as an electron donor for CO2 reduction in photosynthesis – Sulfide oxidized to elemental sulfur (S0) that is stored as globules either inside or outside cells © 2012 Pearson Education, Inc. Figure 17.5 © 2012 Pearson Education, Inc. 17.2 Purple Phototrophic Bacteria • Purple sulfur bacteria (cont’d) – Many can also use other reduced sulfur compounds, such as thiosulfate (S2O32) – All are Gammaproteobacteria – Found in illuminated anoxic zones of lakes and other aquatic habitats where H2S accumulates, as well as sulfur springs (Figure 17.6) © 2012 Pearson Education, Inc. Figure 17.6 © 2012 Pearson Education, Inc. 17.2 Purple Phototrophic Bacteria • Purple nonsulfur bacteria (Figure 17.7) – Organisms able to use sulfide as an electron donor for CO2 reduction – Most can grow photoheterotrophically using light as an energy source and organic compounds as a carbon source © 2012 Pearson Education, Inc. Figure 17.7 © 2012 Pearson Education, Inc. 17.3 The Nitrifying Bacteria • Nitrifying bacteria – Able to grow chemolithotrophically at the expense of reduced inorganic nitrogen compounds – Nitrification (oxidation of ammonia to nitrate) occurs as two separate reactions by different groups of bacteria – Many species have internal membrane systems that house key enzymes in nitrification – Highest numbers in habitats with large amounts of ammonia – Most are obligate chemolithotrophs and aerobes © 2012 Pearson Education, Inc. Figure 17.8 Reaction: NH3 1 12 O2 Reaction: NO2 © 2012 Pearson Education, Inc. 1 2 NO2 H2O O2 NO3 17.4 Sulfur- and Iron-Oxidizing Bacteria • Sulfur-oxidizing bacteria – Grow chemolithotrophically on reduced sulfur compounds – Some obligate chemolithotrophs possess special structures that house Calvin cycle enyzmes © 2012 Pearson Education, Inc. Figure 17.9 © 2012 Pearson Education, Inc. Figure 17.10 © 2012 Pearson Education, Inc. 17.5 Hydrogen-Oxidizing Bacteria • Hydrogen-oxidizing bacteria – Most can grow autotrophically with H2 as sole electron donor and O2 as electron acceptor (“knallgas” reaction) – Contain one or more hydrogenase enzymes that use H2 either to produce ATP or for reducing power for autotrophic growth © 2012 Pearson Education, Inc. Figure 17.13 © 2012 Pearson Education, Inc. 17.6 Methanotrophs and Methylotrophs • Methanotrophs – Use CH4 and a few other one-carbon (C1) compounds as electron donors and source of carbon – Widespread in soil and water – Obligate aerobes – Morphologically diverse – Contain extensive internal membrane systems for methane oxidation © 2012 Pearson Education, Inc. Figure 17.14 © 2012 Pearson Education, Inc. 17.7 Pseudomonas and the Pseudomonads • All genera within the pseudomonad group are – Straight or curved rods with polar flagella – Chemoorganotrophs – Obligate aerobes • Species of the genus Pseudomonas and related genera can be defined on the basis of phylogeny and physiological characteristics © 2012 Pearson Education, Inc. Figure 17.16 © 2012 Pearson Education, Inc. 17.7 Pseudomonas and the Pseudomonads • Pseudomonads – Nutritionally versatile – Ecologically important organisms in water and soil – Some species are pathogenic • Includes human opportunistic pathogens and plant pathogens © 2012 Pearson Education, Inc. 17.8 Acetic Acid Bacteria • Acetic acid bacteria – Organisms that carry out complete oxidation of alcohols and sugars • Leads to the accumulation of organic acids as end products – Motile rods – Aerobic – High tolerance to acidic conditions © 2012 Pearson Education, Inc. 17.8 Acetic Acid Bacteria • Acetic acid bacteria (cont’d) – Commonly found in alcoholic juices • Used in production of vinegar – Some can synthesize cellulose – Colonies can be identified on CaCO3 agar plates containing ethanol © 2012 Pearson Education, Inc. Figure 17.17 © 2012 Pearson Education, Inc. 17.10 Neisseria • Neisseria and their relatives can be isolated from animals, and some species of this group are pathogenic – N. gonorrheae and N. meningitidis – Some of the most naturally competent bacteria known © 2012 Pearson Education, Inc. Figure 17.21 © 2012 Pearson Education, Inc. 17.11 Enteric Bacteria • Enteric bacteria (Figure 17.22) – Phylogenetic group within the Gammaproteobacteria – Facultative aerobes – Motile or nonmotile, nonsporulating rods – Possess relatively simple nutritional requirements – Ferment sugars to a variety of end products © 2012 Pearson Education, Inc. Figure 17.22 © 2012 Pearson Education, Inc. 17.11 Enteric Bacteria • Escherichia – Universal inhabitants of intestinal tract of humans and warm-blooded animals • Synthesize vitamins for host – Some strains are pathogenic © 2012 Pearson Education, Inc. 17.11 Enteric Bacteria • Salmonella and Shigella – Closely related to Escherichia – Usually pathogenic – Salmonella characterized immunologically by surface antigens © 2012 Pearson Education, Inc. 17.11 Enteric Bacteria • Proteus – Genus containing rapidly motile cells; capable of swarming (Figure 17.24) – Frequent cause of urinary tract infections in humans © 2012 Pearson Education, Inc. Figure 17.24 © 2012 Pearson Education, Inc. 17.12 Vibrio, Aliivibrio, and Photobacterium • The Vibrio group – – – – Cells are motile, straight or curved rods Facultative aerobes Fermentative metabolism Best-known genera are Vibrio, Aliivibrio, and Photobacterium – Most inhabit aquatic environments © 2012 Pearson Education, Inc. Figure 17.26 © 2012 Pearson Education, Inc. 17.13 Rickettsias • Rickettsias (Figure 17.27) – Small, coccoid or rod-shaped cells – Most are obligate intracellular parasites – Causative agent of several human diseases © 2012 Pearson Education, Inc. Figure 17.27 © 2012 Pearson Education, Inc. 17.13 Rickettsias • Wolbachia (Figure 17.28) – Genus of rod-shaped Alphaproteobacteria – Intracellular parasites of arthropod insects • Affect the reproductive fitness of hosts © 2012 Pearson Education, Inc. 17.14 Spirilla • Spirilla (Figure 17.29) – Group of motile, spiral-shaped Proteobacteria – Key taxonomic features include • • • • • Cell shape and size Number of polar flagella Metabolism Physiology Ecology © 2012 Pearson Education, Inc. 17.14 Spirilla • Spirilla – Bdellovibrio • • • • • Prey on other bacteria (Figure 17.31) Two stages of penetration (Figure 17.32) Obligate aerobes Members of Deltaproteobacteria Widespread in soil and water, including marine environments © 2012 Pearson Education, Inc. Figure 17.31 © 2012 Pearson Education, Inc. Figure 17.32 Release of progeny Prey lysis (2.5–4 h postattachment) Bdellovibrio Prey cytoplasm Elongation of Bdellovibrio inside the bdelloplast Prey 40–60 min Attachment 5–20 min Bdelloplast Penetration © 2012 Pearson Education, Inc. Prey periplasmic space 17.16 Budding and Prosthecate/Stalked Bacteria • Budding and Prosthecate/Stalked Bacteria – Large and heterogeneous group – Primarily Alphaproteobacteria – Form various kinds of cytoplasmic extrusions bounded by a cell wall (collectively called prosthecae; Figure 17.35) – Cell division different from other bacteria (Figure 17.36) © 2012 Pearson Education, Inc. Figure 17.36 I. Equal products of cell division: Binary fission: most bacteria II. Unequal products of cell division: 1. Simple budding: Pirellula, Blastobacter 2. Budding from Hyphae: Hyphomicrobium, Rhodomicrobium, Pedomicrobium 3. Cell division of stalked organism: Caulobacter 4. Polar growth without differentiation of cell size: Rhodopseudomonas, Nitrobacter, Methylosinus © 2012 Pearson Education, Inc.