Chapter 11 The Prokaryotes: Domains Bacteria and Archaea.
-
Upload
tristan-waye -
Category
Documents
-
view
302 -
download
10
Transcript of Chapter 11 The Prokaryotes: Domains Bacteria and Archaea.
Chapter 11
The Prokaryotes:Domains Bacteria and Archaea
Firmicutes Actinobacteria
Domain Bacteria
• Prokaryotes• Single cell organisms• Circular chromosome• Peptidoglycan cell wall• Binary division
no
Types of Diversity• Morphological 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
Detailed phylogenetic tree of the major lineages (phyla) of Bacteria based on 16S ribosomal RNA sequence comparisons
Firmicutes Actinobacteria
Prokaryotes
Phylum PhylumFirmicutes Actinobacteria
Phylum Firmicutes• Gram-positive
• Low G + C (less than 60%)
• Very popular is the plasmid exchange across species and genera of this phyla.
Orders:
Phylum Firmicutes• Rods:
– Genus Bacillus• Aerobic and facultative anaerobic• Endospore forming rods• Common in soil• Human and animal disease – anthrax, food poisoning
– Genus Clostridium• Obligate anaerobes• Endospore forming rods• 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
Phylum Firmicutes• Coccus
– 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– 0.1 - 0.24 µm– Can grow in filamentous form or single– Human disease - pneumonia M. pneumoniae
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
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
Phylum CyanobacteriaPhylum Spirochetes Phylum ChlamydiaePhylum Bacteroidetes Phylum Fusobacteria
Phylum Proteobacteria
Class (alpha) Class (beta) Class (gamma) Class (delta) Class (epsilon)
• 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
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
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– human pathogen– Gonorrhoea, meningitis
• Genus Zoogloea– aerobic sewage treatment– form precipitating flocs
• 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
Class (gamma) Proteobacteria
Figure 11.7
– 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
Class (gamma) Proteobacteria
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
• 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
Class (epsilon) Proteobacteria
Purple and Green Photosynthetic Bacteria• Oxygenic and Anoxygenic photosynthesis
2H2O + CO2
light
(CH2O) + H2O + O2
2H2S + CO2
light
(CH2O) + H2O + 2S
• 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
Phylum Cyanobacteria
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
• 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
Phylum Chlamydiae
Figure 11.23
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
• Anaerobic
• May be involved in dental diseases
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
Detailed phylogenetic tree of the Archaea based on 16S ribosomal RNA sequence comparisons.
Domain Archaea• Korarchaeota;
– 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.
• 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
Microbial Diversity
Figure 11.26
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.