Prokaryotes Notes

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Learning Objectives

Check Your Understanding

11-1    Differentiate the alphaproteobacteria described in this chapter by drawing a dichotomous key.

Make a dichotomous key to distinguish the alphaproteobacteria described in this chapter. (Hint: See page 292 for a completed example.)

11-2    Differentiate the betaproteobacteria described in this chapter by drawing a dichotomous key.

Make a dichotomous key to distinguish the betaproteobacteria described in this chapter.

11-3    Differentiate the gammaproteobacteria described in this chapter by drawing a dichotomous key.

Make a dichotomous key to distinguish the orders of gammaproteobacteria described in this chapter.

11-4    Differentiate the deltaproteobacteria described in this chapter by drawing a dichotomous key.

Make a dichotomous key to distinguish the deltaproteobacteria described in this chapter.

11-5    Differentiate the epsilonproteobacteria described in this chapter by drawing a dichotomous key.

Make a dichotomous key to distinguish the epsilonproteobacteria described in this chapter.

11-6    Differentiate among planctomycetes, chlamydias, Bacteroidetes, Cytophaga, and Fusobacteria by drawing a dichotomous key.

Which gram-negative group has a life cycle that includes different stages? 

11-7    Compare and contrast purple and green photosynthetic bacteria with the cyanobacteria.

Both the purple and green photosynthetic bacteria and the photosynthetic cyanobacteria use plantlike photosynthesis to make carbohydrates. In what way does the photosynthesis carried out by these two groups differ from plant photosynthesis?

11-8    Describe the features of spirochetes and Deinococcus.

The axial filament distinguishes what genera of bacteria?

11-9    Differentiate the genera of firmicutes described in this chapter by drawing a dichotomous key.

To which genus is Enterococcus more closely related: Staphylococcus or Lactobacillus?

11-10  Differentiate the actinobacteria described in this chapter by drawing a dichotomous key.

What group of bacteria makes most of the commercially important antibiotics?

11-11  Name a habitat for each group of archaea.

What kind of archaea would populate solar evaporating ponds?

11-12  List two factors that contribute to the limits of our knowledge of microbial diversity.

How can you detect the presence of a bacterium that cannot be cultured?

 

Introduction (p. 290)

  1. Bergey’s Manual categorizes bacteria into taxa based on rRNA sequences.
  2. Bergey’s Manual lists identifying characteristics such as Gram stain reaction, cellular morphology, oxygen requirements, and nutritional properties.

The Prokaryotic Groups (pp. 291–292)

ASM 1.2: Mutations and horizontal gene transfer, and the immense variety of microenvironments have selected for a huge diversity of microorganisms.

  1. Prokaryotic organisms are classified into two domains: Archaea and Bacteria.

Domain Bacteria (pp. 292–313)

  1. Bacteria are essential to life on Earth.

The Gram-Negative Bacteria (pp. 292–307)

The Proteobacteria (pp. 292–302)

  1. Members of the phylum Proteobacteria are gram-negative.
  2. Alphaproteobacteria includes nitrogen-fixing bacteria, chemoautotrophs, and chemoheterotrophs.
  3. Betaproteobacteria includes chemoautotrophs and chemoheterotrophs.
  4. Pseudomonadales, Legionellales, Vibrionales, Enterobacteriales, and Pasteurellales are classified as gammaproteobacteria.
  5. Bdellovibrio and Myxococcus in the deltaproteobacteria prey on other bacteria.
  6. Epsilonproteobacteria includes Campylobacter and Helicobacter.

The Nonproteobacteria Gram-Negative Bacteria (pp. 302–307)

  1. Cyanobacteria are photoautotrophs that use light energy and CO2 and do produce O2.
  2. Purple and green photosynthetic bacteria are photoautotrophs that use light energy and CO2 and do not produce O2.
  3. Deinococcus and Thermus are resistant to environmental extremes.
  4. Planctomycetes, Chlamydiae, Spirochetes, Bacteriodetes, and Fusobacteria are phyla of gram-negative, chemoheterotrophic bacteria.

The Gram-Positive Bacteria (pp. 308–313)

  1. In Bergey's Manual, gram-positive bacteria are divided into those that have low G + C ratio and those that have high G + C ratio.
  2. Low G + C gram-positive bacteria include common soil bacteria, the lactic acid bacteria, and several human pathogens.
  3. High G + C gram-positive bacteria include mycobacteria, corynebacteria, and actinomycetes.

Domain Archaea (p. 314)

  1. Extreme halophiles, extreme thermophiles, and methanogens are included in the archaea.

Microbial Diversity (pp. 315–316)

ASM 5.1: Microorganisms are ubiquitous and live in diverse and dynamic ecosystems.

ASM 6.4: Because the true diversity of microbial life is largely unknown, its effects and potential benefits have not been fully explored.

  1. Few of the total number of different prokaryotes have been isolated and identified.
  2. PCR can be used to uncover the presence of bacteria that can’t be cultured in the laboratory.