Transcript Lecture 12

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
Prokaryotes
Firmicutes
Actinobacteria
Phylum
Firmicutes
Phylum
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
• Coccus
Phylum Firmicutes
– 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 Proteobacteria
Class  (alpha)
Class  (beta)
Class  (gamma)
Class  (delta)
Class (epsilon)
Phylum Cyanobacteria
Phylum Spirochetes
Phylum Chlamydiae
Phylum Bacteroidetes
Phylum Fusobacteria
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.
•
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
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
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
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
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
Purple and Green Photosynthetic Bacteria
• Oxygenic and Anoxygenic photosynthesis
light
2H2O + CO2
(CH2O) + H2O + O2
light
2H2S + CO2
(CH2O) + H2O + 2S
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
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
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
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.
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
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.