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
