Proteobacteria and Alphaproteobacteria Overview
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Questions and Answers

What accounts for more than a third of characterized bacteria species?

Proteobacteria

What type of bacteria are all Proteobacteria?

  • Gram-negative (correct)
  • Gram-positive
  • Alkaliphilic
  • Acidophilic

    • Which of the following is NOT a mechanism involved in energy generation by Proteobacteria?

  • Phototrophic
  • Chemoorganotrophic
  • Chemolithotrophic
  • Aerobic respiration (correct)

    • Proteobacteria are classified into six classes.

    <p>True</p> Signup and view all the answers

    Horizontal gene flow has likely played a role in shaping the metabolic diversity of Proteobacteria.

    <p>True</p> Signup and view all the answers

    What is the approximate number of described species within the Alphaproteobacteria class?

    <p>1,000</p> Signup and view all the answers

    Which of these characteristics applies to most Alphaproteobacteria?

    <p>Both B and C</p> Signup and view all the answers

    Most Alphaproteobacteria species are oligotrophic.

    <p>True</p> Signup and view all the answers

    Which of these orders is NOT included within Alphaproteobacteria?

    <p>Bacteroidales</p> Signup and view all the answers

    Which group of bacteria can form root nodules and fix nitrogen in symbiosis with leguminous plants?

    <p>Rhizobia</p> Signup and view all the answers

    What is the name of the plant pathogen that causes crown gall disease and is closely related to Rhizobium?

    <p>Agrobacterium tumefaciens</p> Signup and view all the answers

    What are methylobacterium often called due to their pink colonies and ability to grow on methanol?

    <p>pink-pigmented facultative methylotrophs</p> Signup and view all the answers

    What type of pathogens are Bartonella?

    <p>intracellular pathogens</p> Signup and view all the answers

    What is a distinctive feature of Pelagibacter ubique?

    <p>It is an oligotroph and obligately aerobic chemoorganotroph</p> Signup and view all the answers

    All Rickettsiales are obligate intracellular parasites or mutualists of animals.

    <p>True</p> Signup and view all the answers

    Which of these human diseases is NOT caused by Rickettsia?

    <p>Lyme disease</p> Signup and view all the answers

    What is the name of the intracellular parasite of many insects that can affect their reproduction by inducing parthenogenesis, killing males, or feminizing them ?

    <p>Wolbachia</p> Signup and view all the answers

    Rhodobacterales and Rhodospirillales are known for their metabolic diversity, exhibiting traits such as nitrogen fixation, denitrification, and methylotrophy.

    <p>True</p> Signup and view all the answers

    What are Caulobacterales typically described as?

    <p>oligotrophic and strictly aerobic chemoorganotrophs</p> Signup and view all the answers

    What is Sphingomonas known for?

    <p>its ability to metabolize various organic compounds, including environmental contaminants.</p> Signup and view all the answers

    How does the bacterium Zymomonas contribute to the production of ethanol?

    <p>It ferments sugars into ethanol.</p> Signup and view all the answers

    What is the third-largest class of Proteobacteria?

    <p>Betaproteobacteria</p> Signup and view all the answers

    Betaproteobacteria contains six orders with many characterized species.

    <p>True</p> Signup and view all the answers

    Which of the following orders is NOT included within Betaproteobacteria?

    <p>Vibrionales</p> Signup and view all the answers

    Burkholderiales exhibit a diverse range of metabolic characteristics, including aerobic, facultatively aerobic, and anaerobic chemoorganotrophs, as well as anoxygenic phototrophs, chemolithotrophs, nitrogen fixers, and pathogens.

    <p>True</p> Signup and view all the answers

    Burkholderia, a key genus within Burkholderiales, is known for its versatile metabolic capabilities, including the ability to degrade organic compounds, promote plant growth, and act as an opportunistic pathogen.

    <p>True</p> Signup and view all the answers

    What is the name of the opportunistic human pathogen within Burkholderia that can cause lung infections?

    <p>Burkholderia cepacia</p> Signup and view all the answers

    Which order within Betaproteobacteria is known for its diverse metabolic and ecological characteristics, including photoheterotrophy and respiration?

    <p>Rhodocyclales</p> Signup and view all the answers

    Rhodocyclus, a genus within Rhodocyclales, is known for its ability to grow best as photoheterotrophs, though it can also grow as photoautotrophs or through respiration in darkness.

    <p>True</p> Signup and view all the answers

    Zoogloea, another important genus within Rhodocyclales, is known for its aerobic chemoorganotrophic metabolism and the production of a thick gelatinous capsule. This capsule plays a significant role in wastewater treatment, contributing to flocculation (forming clumps) and settling of solids.

    <p>True</p> Signup and view all the answers

    What is the name of the species within Zoogloea that is particularly important in aerobic wastewater treatment, degrading organic carbon and promoting flocculation and settling?

    <p>Zoogloea ramigera</p> Signup and view all the answers

    Neisseriales include at least 29 genera of diverse chemoorganotrophs.

    <p>True</p> Signup and view all the answers

    What type of bacteria are Neisseria?

    <p>cocci</p> Signup and view all the answers

    Which Neisseria species is known to cause meningitis?

    <p>N. meningitidis</p> Signup and view all the answers

    What is the Neisseria species that causes gonorrhoea?

    <p>N. gonorrhoeae</p> Signup and view all the answers

    What is the name of the rod-shaped bacterium closely related to Neisseria that produces the purple pigment violacein, which has antimicrobial and antioxidant properties?

    <p>Chromobacterium violaceum</p> Signup and view all the answers

    Most Hydrogenophilales, Methylophilales, and Nitrosomonadales are obligate aerobes, and many are autotrophic.

    <p>True</p> Signup and view all the answers

    What is the name of the facultative chemolithotroph within Hydrogenophilales that can use H2 as an electron donor and fix CO2 using the Calvin cycle, but can also grow as a chemoorganotroph?

    <p>Hydrogenophilus thermoluteolus</p> Signup and view all the answers

    What are Thiobacillus described as?

    <p>chemoorganotrophs or chemolithotrophs</p> Signup and view all the answers

    Chemolithotrophic Thiobacillus are sulfur bacteria that oxidize reduced sulfur compounds and can fix CO2.

    <p>True</p> Signup and view all the answers

    What kind of organisms are Methylophilus primarily?

    <p>obligate and facultative methylotrophs</p> Signup and view all the answers

    What are Nitrosomonadales described as?

    <p>obligately chemolithotrophic ammonia-oxidizing bacteria</p> Signup and view all the answers

    Nitrosomonas and Nitrosospira are key genera within Nitrosomonadales.

    <p>True</p> Signup and view all the answers

    Study Notes

    Proteobacteria

    • Largest and most diverse phylum of bacteria
    • Accounts for over a third of characterized bacterial species
    • All are gram-negative
    • Show various energy generation mechanisms (chemolithotrophic, chemoorganotrophic, phototrophic)
    • Six classes: Alpha, Beta, Gamma, Delta, Epsilon, and Zetaproteobacteria
    • Horizontal gene transfer likely shaped metabolic diversity

    Alphaproteobacteria

    • Second-largest class of Proteobacteria
    • About 1,000 described species
    • Mostly obligate or facultative aerobes
    • Many are oligotrophic (prefer low nutrient environments)
    • Key orders include Rhizobiales, Rickettsiales, Rhodobacterales, Rhodospirillales, Caulobacterales, and Sphingomonadales
    • Key genera include Rhizobia (nitrogen-fixing bacteria), Agrobacterium tumefaciens (crown gall disease), Methylobacterium (pink biofilms), Bartonella (intracellular pathogens), and Pelagibacter ubique (abundant in ocean)
    • Rickettsiales: obligate intracellular parasites, often transmitted by arthropods

    Betaproteobacteria

    • Third-largest Proteobacteria class
    • About 500 described species
    • Diverse metabolic functions
    • Six orders: Burkholderiales, Hydrogenophilales, Methylophilales, Neisseriales, Nitrosomonadales, and Rhodocyclales
    • Key genera include Burkholderia (bioremediation, some pathogens), Rhodocyclus (photoheterotrophs or photoautotrophs) and Zoogloea (flocculation in wastewater)

    Gammaproteobacteria

    • Largest and most diverse Proteobacteria class
    • Over 1500 characterized species
    • Diverse metabolism (phototrophic, chemoorganotrophic, chemolithotrophic)
    • Respiratory or fermentative metabolisms
    • Enterobacteriales (enteric bacteria) is a key order within Gammaproteobacteria
    • Characteristics of Enterobacteriales: facultative aerobes, gram-negative, nonsporulating rods, oxidase-negative and catalase-positive, produce acid from glucose, simple nutritional requirements
    • Fermentation patterns: mixed-acid and 2,3-butanediol fermentations
    • Key genera include Escherichia coli, Salmonella, Shigella, and Proteus (mixed-acid), Enterobacter, Klebsiella, and Serratia (butanediol)

    Deltaproteobacteria and Epsilonproteobacteria

    • Deltaproteobacteria: primarily sulfate-reducing bacteria, dissimilative iron-reducers, bacterial predators; key genera include Myxococcales (predators) and Desulfuromonadales (sulfate reducers)
    • Epsilonproteobacteria: oxidize H2S, abundant at oxygen-rich environments; key genera include Campylobacter (gastroenteritis) and Helicobacter (peptic ulcers)

    Other Groups

    • Rhodobacterales and Rhodospirillales: metabolically diverse
    • Caulobacterales: oligotrophic, strictly aerobic chemoorganotrophs
    • Sphingomonadales: diverse aerobic/facultative aerobic chemoorganotrophs
    • Neisseriales: diverse chemoorganotrophs, some pathogenic (Neisseria)
    • Hydrogenophilales, Methylophilales, and Nitrosomonadales: chemolithotrophic/methylotrophic, obligate aerobes
    • Vibrionales: facultatively aerobic rods/curved rods with fermentative metabolism, often aquatic species (Vibrio cholerae, Vibrio parahaemolyticus)
    • Pseudomonadales: chemoorganotrophs, often oxidase- and catalase-positive, diverse species including pathogens

    Firmicutes, Tenericutes, and Actinobacteria

    • Account for about half of all characterized bacterial species
    • Actinobacteria: primarily filamentous soil bacteria with high GC content in their DNA
    • Tenericutes: cells that lack a cell wall
    • Firmicutes: include endospore-forming bacteria, lactic acid bacteria, and other groups, generally with low GC content in their DNA

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    Proteobacteria PDF

    Description

    Explore the fascinating diversity of Proteobacteria, the largest phylum of bacteria, which includes six distinct classes. This quiz focuses on the characteristics and significance of Alphaproteobacteria and key genera like Rhizobia and Agrobacterium. Test your knowledge on bacterial metabolism and ecological roles in varied environments.

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