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The Prokaryotes: Domains Bacteria and Archaea
Chapter 11 The Prokaryotes: Domains Bacteria and Archaea
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Firmicutes Actinobacteria
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Domain Bacteria Prokaryotes Single cell organisms Circular chromosome
Peptidoglycan cell wall Binary division no
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Types of Diversity Morphological diversity: Structural diversity:
Bacilli, cocci, and spirals are 3 common shapes Filamentous forms, pleiomorphic forms. There are many varieties of size, ranging from submicroscopic up to a few bacteria that can be seen with the naked eye. Structural diversity: Cell wall Gram-positive and gram-negative bacteria. Absence of walls External appendages Endospores Metabolic diversity: Heterotrophs vs autotrophs. Fermentation vs respiration. Aerobic and anaerobic. Photosynthesis Genetic diversity: Small ribosomal subunit sequencing – 16S r RNA
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Detailed phylogenetic tree of the major lineages (phyla) of Bacteria based on 16S ribosomal RNA sequence comparisons
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Firmicutes Actinobacteria
Prokaryotes
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Phylum Phylum Firmicutes Actinobacteria
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Phylum Firmicutes Gram-positive Low G + C (less than 60%)
Very popular is the plasmid exchange across species and genera of this phyla. Orders:
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Phylum Firmicutes Rods: Genus Bacillus Genus Clostridium
Aerobic and facultative anaerobic Endospore forming rods Common in soil Human and animal disease – anthrax, food poisoning Genus Clostridium Obligate anaerobes Toxin produced Human pathogens – tetanus, botulism, gangrene, diarrhea Genus Lactobacillus Generally aerotolerant anaerobes, lack an electron-transport chain Lactic acid fermentation of carbohydrates Used for yogurt, buttermilk, pickles, sauerkraut Live on human mucous – oral cavity, vagina, intestine Genus Listeria Can grow at 4°C Contaminant of meat and dairy Survive phagocytosis Cross placenta cause fetus damages
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Phylum Firmicutes Coccus Genus Mycoplasma Genus Staphylococcus
Coci in clusters Tolerate high osmotic pressure Live on human skin and nose Human disease – food poisoning, toxic shock syndrome Genus Streptococcus Coci in chain Produce tissue and cell digesting enzymes and toxins Avoid phagocytosis Human disease – pharyngitis, dental caries, scarlet fever, impetigo, rheumatic fever, neonatal sepsis Genus Enterococcus Live on human mucous - oral cavity, vagina, intestine Antibiotic resistant Human disease – nosocomial infections, surgical wounds, urinary tract infections Genus Mycoplasma No cell wall, sterols in membrane, pleomorphic µm Can grow in filamentous form or single Human disease - pneumonia M. pneumoniae
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Phylum Actinobacteria
Gram-positive - High G + C (more than 60%) Coccoid, rod-coccoid , fragmenting hyphal forms, filamentous with permanent and highly differentiated branched mycelium Physiologically very diverse production of numerous extracellular enzymes, including antibiotics
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Phylum Actinobacteria
Genus Mycobacterium usually bacilli, slow growth cell wall has mycolic acid (acid fast) human diseases: leprosy and tuberculosis Genus Propionibacterium rod shape, form propionic acid on human skin, cause acne. Genus Cornebacterium rods, pleomorphic human disease: diphtheria Genus Streptomyces aerobes, filamentous, common in soil produce external asexual spores produce many antibiotics Genus Actinomyces facultative anaerobes, filamentous, in human oral mucous human disease: actinomycosis Genus Nocardia aerobes, filamentous, reproduce by fragmentation acid fast, in soil human disease: pulmonary infections, mycetoma
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Phylum Cyanobacteria Phylum Spirochetes Phylum Chlamydiae Phylum Bacteroidetes Phylum Fusobacteria Phylum Proteobacteria Class (alpha) Class (beta) Class (gamma) Class (delta) Class (epsilon)
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Phylum Proteobacteria
Mythical Greek god, Proteus, who could assume many shapes Proteobacteria is the largest group of bacteria. This phylum contains 2086 species or 32.3% of all known bacteria. Proteobacteria are all gram negative. All four of major nutrition types are present Purple phototrophic. Nitrifying bacteria Enteric bacteria Bacteria responsible for animal bioluminescence. Many pathogens. More morphologically unusual bacteria. Symbiotic genera. Phylum Proteobacteria
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Class (alpha) Proteobacteria
Obligate pathogen Genus Rikettsia Induce phagocytosis and multiplies in phagocytes Transmitted via flea and tick bites Human disease – spotted fever: typhus, Rocky Mountain – damage the permeability of blood capillaries. Genus Ehrlichia Lives in white blood cells- phagocytes Transmitted via tick bite Human disease ehrlichiosis Human pathogens Genus Bartonella Transmitted via cat saliva Human disease – cat-scratch disease Genus Brucella Survives phagocytosis Human disease brucellosis Plant pathogens Genus, Bradyrhizobium, Agrobacterium Industrially important Genus Acetobacter, Glaunobacter Convert ethanol to acetic acid Nitrogen fixation Genus Rhizobium, Azospirilum Grow on roots
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The (beta) Proteobacteria
Genus Spirillum spiral, motile: polar flagella in fresh water human disease: rat bite fever transmitted via rodent bite or fecal contamination Genus Burkholderia motile: single polar flagellum Diverse carbon source grow in disinfectants human disease: respiratory infections Genus Bordetella human pathogen whooping cough/pertussis Genus Neisseria on mucus membranes of mammals Gonorrhoea, meningitis Genus Zoogloea aerobic sewage treatment form precipitating flocs
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Class (gamma) Proteobacteria
Genus Pseudomonas Opportunistic pathogens Metabolically diverse Motile -polar flagella Produce water soluble blue pigment Can live on soap, adhesives, antiseptics Can grow at 4°C: food spoilage Antibiotic resistant Wound infections, infections in immunocompromized patients Genus Vibrio: curved rod, Found in coastal water Vibrio cholerae causes cholera Genus Legionella Live in fresh water Contaminant of AC ducts Human disease – Legionnaire’s disease Genus Azotobacter and Azomonas Nitrogen fixing Figure 11.7
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Class (gamma) Proteobacteria
Order Enterobacteriales facultative anaerobes, ferment carbohydrates Peritrichous flagella, Have fimbriae and Sex pili Produce bacteriocins Human pathogens, most cause gastrointestinal, urinary or respiratory tract infections Escherichia Normal microbiota, can cause gastroenteritis, UTIs Salmonella Common animal microbiota Toxin cause salmonellosis Shigella Toxin cause shigellosis Enterobacter In soil, water, animals and humans, can cause nosocomial and UTIs Klebsiella In soil and water, can fix nitrogen, can cause pneumonia Proteus Swarming growth, wound infections Serratia Red pigment , can cause respiratory and UTIs Yersinia Black Death plaque, transmitted via fleas from rats and ground squirrels Erwinia Plant pathogen – hydrolyze pectin: plant rot
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Class (delta) Proteobacteria
Include some bacteria that have predators on other bacteria Important contribution to sulfur cycle. Genus Bdellovibrio motile: single polar flagella attacks other Gram negative bacteria reproduces in periplasm Genus Myxococcus motile via slime trails digest bacteria low nutrients: aggregate to form a fruiting body ! myxospores
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Class (epsilon) Proteobacteria
Slender gram-negative rods that are curved to spirilloid Flagella – one polar flagellum or multiple flagella Pathogens - peptic ulcers, stomach - flagellated Unicellular to multicultural filamentous and colonial type Genus Campylobacter animal disease: spontaneous abortion human disease: food borne intestinal disease Genus Helicobacter human disease: peptic ulcers
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Purple and Green Photosynthetic Bacteria
Oxygenic and Anoxygenic photosynthesis light 2H2O + CO2 (CH2O) + H2O + O2 light 2H2S + CO2 (CH2O) + H2O + 2S
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Phylum Cyanobacteria The only bacteria that carry out oxygenic photosynthesis Some growth in associations with plants and animals CO2 fixation, Fix nitrogen Gliding motility The chloroplasts found in all photosynthesized organisms evolved from this group of bacteria
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Phylum Spirochetes Coiled morphology
Axial filament-enclosed in the space between the outer sheath and the body of the cell Number of important pathogenic bacteria Treponema – syphilis Borrelia – lyme disease, transmitted via tick from mice Leptospira – leptospirosis, transmitted via animal urine contaminated water
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Phylum Chlamydiae No peptidoglycan Divide in animal cell
Produce spore-like elementary bodies C. trachomatis Trachoma Urethritis Pelvic inflammatory disease C. pneumoniae Pneumonia C. psittaci Causes psittacosis Figure 11.23
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Bacteroidetes and Fusobacteria
Phylum Bacteroidetes Anaerobic In mouth and large intestine Cellulose-degrading in soil Genus Bacteroides In human and animal GIT, can infect puncture wound and peritoneum Genus Cytophaga In soil, degrade cellulose Phylum Fusobacteria Fusobacterium Found in mouth May be involved in dental diseases
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Domain Archaea Cell wall - No peptidoglycan
Unusual metabolism that allow them to live in the most inhospitable places on Earth (extreme environments) Oxygen-free habitats Boiling sulfuric acid pools near volcanoes Sulfur hot springs Glacial ice Methane seeps Desert sands Acid mines Oil leaks Polluted waters Toxic waste dumps
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Detailed phylogenetic tree of the Archaea based on 16S ribosomal RNA sequence comparisons.
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Domain Archaea Korarchaeota; Crenarchaeota: Euryarchaeota:
Found only in high temperature hydrothermal environments (hot springs). None have been grown in pure culture. Crenarchaeota: They use sulfur compounds as electron donors or as acceptors. Most thermophilic organisms known. Significant in deep-sea environment and as wall as in polar seas Euryarchaeota: Methanogens - microorganisms that produce methane as a metabolic byproduct in anoxic conditions Halophiles - extremophile organisms that live in environments with very high concentrations of salt. ("salt-loving“). Thermophiles Nanoarhaeota recently discovered smallest organism, nanosized, hyperthermophilic symbiont.
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Microbial Diversity Bacteria size range Thiomargarita (750 µm)
Nanoarhaeota (0.4 µm) PCR indicates up to 10,000 bacteria/g of soil. Many bacteria have not been identified or characterized because they haven't been cultured Need to be cultured to understand their metabolism and ecological role Need special nutrients Are part of complex food chains requiring the products of other bacteria Figure 11.26
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Learning objectives Distinguish among the alpha proteobacteria .
Distinguish among the beta proteobacteria. Distinguish among the orders of gamma proteobacteria . Distinguish among the delta proteobacteria. Distinguish among the epsilon proteobacteria. Compare and contrast the green and purple photosynthetic bacteria with the cyanobacteria. Distinguish among the low G + C gram-positive bacteria. Distinguish among the high G + C gram-positive bacteria. Distinguish among the gram-negative nonproteobacteria. Distinguish, spirochetes, Bacteroidetes, and Fusobacteria.
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