Unit IV.B The Prokaryotes (Gram-Negative Proteobacteria) Flashcards
include most of the gramnegative, chemoheterotrophic bacteria, are presumed to have arisen from a common photosynthetic ancestor
proteobacteria
Five Classes of Gram-Negative Proteobacteria
1.Alphaproteobacteria
2.Betaproteobacteria
3.Gammaproteobacteria
4.Deltaproteobacteria
5.Epsilonproteobacteria
- includes most of the proteobacteria that are capable of growth with very low levels of nutrients. Some have unusual morphology, including protrusions such as stalks or buds known as** prosthecae.**
- also include agriculturally important bacteria capable of** nitrogen fixation** in symbiosis with plants, and several plant and human pathogens.
The α (alpha) Proteobacteria
- most abundant microorganisms on Earth, certainly in the ocean environment
- member of a group of marine microbes named SAR 11 → Sargasso Sea.
- extremely small (~0.3nm) → survive in low nutrient environments
Pelagibacter
- Nitrogen-fixing bateria
- a soil bacterium that grows in close association with the roots of many plants,
- It uses nutrients excreted by the plants and in return fixes nitrogen from the atmosphere.
Azospirillum
Produce acetic acid from ethyl alcohol
Acetobacter & Gluconobacter - Industrially important aerobic organisms that convert ethanol into acetic acid (vinegar).
Granulibacter - emerging pathogen found in patients with chronic granulomatous disease
Acetobactereceae
- Obligate intracellular parasites (reproduce only within a mammalian cell)
- that they are transmitted to humans by insect and tick bites
- Arthropod-borne, spotted fevers
Rickettsia
- Obligate intracellular parasites
- transmitted by ticks to humans and cause ehrlichiosis, a sometimes fatal disease
- Tick-born, live obligately within white blood cells
Ehrlichia
- Have prosthecae that increases their nutrient uptake because they are exposed to a continuously changing flow of water and because the stalk increases the surface-to-volume ratio of the cell
Caulobacter
- Have prosthecae
- Hyphomicrobium. Budding bacteria found in lakes
- found in low-nutrient aquatic environments and have even been found growing in laboratory water baths.
Hyphomicrobium
- Plant pathogen
- infect the roots of leguminous plants
- known by the common name of rhizobia. The presence of rhizobia in the roots leads to formation of nodules in which the rhizobia and plant form a symbiotic relationship, resulting in the fixation of nitrogen from the air for use by the plant
Rhizobium & Bradyrhizobium
- Human pathogen
- B. hensela e- Cat-scratch disease
Bartonella
Human Pathogen
small nonmotile coccobacilli & obligate parasites of mammals
Brucellosis
B. abortus (cattle), B. canis (dogs), B. suis (pigs), B. melitensis (sheep & goats)
Brucella
genera of nitrifying bacteria that are of great importance to the environment and to agriculture.
Nitrobacter and Nitrosomonas
- Obligate intracellular parasites
- most common infectious bacterial genus in the world; they live only inside the cells of their hosts, usually insects
- → dengue & Zika viruses control
Wolbachia
constitute the largest subgroup of the proteobacteria and include a great variety of physiological types.
The γ (gamma) Proteobacteria
- Chemoautotrophic, oxidize hydrogen sulfide (H2S) to elemental sulfur (S0) for energy
- esembles certain filamentous cyanobacteria ,but it is not photosynthetic
- Its motility is enabled by the production of slime, which attaches to the surface on which movement occurs and provides lubrication, allowing the organism to glide.
Beggiatoa
Order Thiotrichales
- Chemoheterotrophic
- a genus of small, pleomorphic bacteria that grow only on complex media enriched with blood or tissue extracts
- F. tularensis: cause tularemia or deerfly fever
Francisella
Order Thiotrichales
aerobic rods or cocci, Opportunistic pathogens, Metabolically diverse, Polar flagella, Excrete extracellular, water-soluble pigments that diffuse into their media
very common in soil and other natural environments
Pseudomonas
Pseudomonadales Order
nitrogen-fixing bacteria, free-living in soil
Azotobacter and Azomonas
Pseudomonadales Order
- are strictly aerobic coccobacilli—that is, intermediate in shape between cocci and rods.
- (Moraxella lacunata is implicated in conjunctivitis, an inflammation of the conjunctiva, the membrane that covers the eye and lines of the eyelids)
Moraxella
Pseudomonadales Order
- A. baumanii - resistant to most available antibiotics; respiratory pathogen but it also infects skin, soft tissues, and wounds and occasionally invades the bloodstream
Acinetobacter
Pseudomonadales Order
- Found in streams, warm-water pipes, cooling towers
- L. Pneumophilia - Legionaire’s disease (pneumonia-type) & Pontiac fever (flu-like)
Legionella
Legionaellales Order
this bacteria require a mammalian host cell to reproduce.
Coxiella
Legionaellales Order
- Facultative anaerobic rods that are often slightly curved
- Found in coastal water
Vibrionales Order
- causes cholera. The disease is characterized by a profuse and watery diarrhea.
- auses a less serious form of gastroenteritis.
- Vibrio cholerae
- V. parahaemolyticus
they inhabit the intestinal tracts of humans and other animals.
Enterobacteriales Order
- a common inhabitant of the human intestinal tract and is probably the most familiar organism in microbiology
- Laboratory pet
- not usually pathogenic
Escherichia coli ( E. coli O157:H7)
Enterobacteriales Order
- Mostly are pathogenic
- Inhabit intestinal tracts of many animals, especially poultry and cattle & can contaminate food
Salmonella
Enterobacteriales Order
- Found only in humans
- bacillary dysentery or shigellosis
Shigella
Enterobacteriales Order
- Found in soil or water
- Nitrogen fixation
- K. pneumoniae cause serious form of pneumonia in humans.
Klebsiella
Enterobacteriales Order
- This genus of bacteria is implicated in many infections of the** urinary tract and in wounds.**
Proteus
Enterobacteriales Order
- Y. pestis causes plague, carries by rats and ground squirrels; fleas transmit it among animals and to humans.
Yersinia
Enterobacteriales Order
- Plant pathogens plant soft-rot disease
- produce enzymes that hydrolyze the pectin between individual plant cells → plant cells to separate from each other → soft-rot
Erwinia
Enterobacteriales Order
Enterobacteriales Order* E. cloacae & E. aerogenes: urinary tract infections and healthcare-associated infections.
* Distributed in humans and animals, as well as in water, sewage, and soil.
Enterobacter
Enterobacteriales Order
- facultative anaerobic, motile, and with seven species
- C. sakazakii: meningitis and necrotizing enterocolitis in infants
Cronobacter
Enterobacteriales Order
nonmotile; they are best known as human and animal pathogens.
Pasteurellales Order
- pathogen of domestic animals
- Cause pneumonia and septicemia
- P. multocida: be transmitted to humans by dog and cat bites.
Pasteurella
Pasteurellales Order
inhabit the mucous membranes of the upper respiratory tract, mouth, vagina, and intestinal tract.
Haemophilus
Pasteurellales Order
distinctive in that they include some bacteria that are** predators on other bacteria**
The δ (delta) Proteobacteria
- Prey on other bacteria
- use H2S either as part of photosynthesis or as an autotrophic energy source
Bdellovibrio
- Use oxidized forms of sulfur, such as sulfates (SO42-) or elemental sulfur (S0)instead of O2 as final electron acceptor→ H2S
- found in anaerobic sediments and in the intestinal tracts of humans and animals
Desulfovibrionales
- Fruiting & Gliding. Vegetative cells of the myxobacteria (myxo = mucus) move by gliding and leave behind a slime trail.
- Myxococcus xanthus & M. fulvus - as they move, their source of nutrition is the bacteria they encounter, enzymatically lyse, and digest
Myxococcales
resting cells of myxococcales
myxospores
slender gram-negative rods that are helical or curved. There are two important genera, both of which are motile by means of flagella and are microaerophilic.
The ε (epsilon) Proteobacteria
- microaerophilic vibrios
- each cell has one polar flagellum
- C. fetus: causes spontaneous abortion in domestic animals.
- C. jejuni: is a leading cause of outbreaks of foodborne intestinal disease.
Campylobacter
- Microaerophilic curved rods
- Multiple flagella
- Helicobacter pylori : most common cause of peptic ulcers in humans, cause of stomach cancer
Helicobacter
