Deck 16: Diversity of Bacteria

Question 1

Which of the following is NOT true of Epsilonproteobacteria?

A) They include the genera Campylobacter and Helicobacter.
B) Many species require relatively low O₂ levels to grow.
C) Epsilonproteobacteria are present in freshwater, marine systems, and terrestrial environments.
D) Epsilonproteobacteria are prolific metal reducers.

Answer 1

D

Question 2

Which of the following organisms is most likely to form a relationship with Syntrophobacter wolinii?

A) a bacterium that oxidizes acetate
B) a bacterium that consumes sulfate
C) a bacterium that consumes H₂
D) a bacterium that consumes pyruvate

Answer 2

C

Question 3

Which feature(s) differentiate(s) Actinobacteria from Firmicutes?

A) absence/presence of a cell wall
B) endospore production capability
C) motility and chemotaxis abilities
D) relative G+C content in their genomes

Answer 3

D

Question 4

Which of the following is NOT a trait of rickettsias?

A) They are obligate intracellular parasites.
B) They lack cell walls.
C) They have not been cultivated in the absence of host cells.
D) Both the host and parasite are required in order to be alive and metabolically active.

Question 5

A pink-pigmented facultative methylotrophic bacterium is LEAST likely to be classified as a member of

A) Rhizobiales.
B) Rhodobacter.
C) Methylobacterium.
D) Proteobacteria.

Question 6

Which of the following best distinguishes deltaproteobacteria from epsilonproteobacteria?

A) Deltaproteobacteria are most commonly found at anoxic-oxic interfaces while epsilonbacteria are most commonly found in anoxic environements.
B) Many epsilonbacteria oxidize sulfur compounds, which could be produced by a sulfur-reducing deltaproteobacterium.
C) A sulfate-reducing epsilonbacterium produces sulfite, which a deltaproteobacterium reduces further to hydrogen sulfide.
D) An epsilonbacterium reduces sulfur compounds whereas all deltaproteobacteria oxidize sulfur compounds.

Question 7

Which taxon is NOT gram-positive?

A) Actinobacteria
B) Firmicutes
C) Sphingobacteria
D) Streptococcus

Question 8

Which phylum harbors the most functional diversity observed and also has the most cultured representatives?

A) Actinobacteria
B) Bacteroidetes
C) Firmicutes
D) Proteobacteria

Question 9

A pseudomonad that loses its R plasmid in the soil is LEAST likely to

A) cause an infection in a human.
B) colonize a surface.
C) infect a shrub.
D) survive a habitat dominated by antibiotic-producing Streptomyces spp.

Question 10

Which characteristic is NOT associated with Vibrio spp.?

A) aquatic
B) gliding motility
C) gram-negative
D) pathogenic

Question 11

Biosynthesis of vitamin K (menaquinone) by ________ spp. inhabiting the ________ of humans is a potentially important mutualistic relationship for human health.

A) Bifidobacterium / intestinal tract
B) Bifidobacterium / stomach
C) Escherichia / intestinal tract
D) Escherichia / stomach

Question 12

Treating wastewater requires the removal of organic material, and an ideal phenotype of a bacterium to do this would flocculate to make the cells settle (rather than staying in suspension) in a wastewater stream. Which species would be best for this application?

A) Bartonella quintana
B) Burkholderia cepacia
C) Wolbachia pipientis
D) Zoogloea ramigera

Question 13

A gram-negative, obligately aerobic, bacillus-shaped bacterium that can degrade a large variety or aromatic compounds (making them potentially useful for bioremediation) is likely a(n)

A) actinobacterium.
B) enteric.
C) pseudomonad.
D) sphingomonad.

Question 14

Chemolithotrophic ammonia-oxidization is a metabolic requirement for members of

A) Nitrosomonas.
B) Nitropseudomonas.
C) Nitrosomonas and Nitrosospira.
D) Nitrosomonas, Nitrosospira, and Nitropseudomonas.

Question 15

Which of the following is NOT a member of the Deltaproteobacteria?

A) Campylobacter
B) Desulfovibrio
C) Geobacter
D) Syntrophobacter

Question 16

While not all members of ________ are pathogenic, two medically relevant species cause meningitis and gonorrhea in humans.

A) Enterobacter
B) Neisseria
C) Shigella.
D) Staphylococcus

Question 17

Which of the following traits is NOT a characteristic of Caulobacter?

A) abundant in aquatic habitats rich in nutrients
B) produces a cytoplasmic outgrowth (prostheca)
C) aerobic chemoorganotrophs
D) asymmetric cell division

Question 18

Which genus would you most likely find in the photic layer of the oceans due to its abundance and aerobic chemoorganotrophic phenotype?

A) Acetobacter
B) Nitrosomonas
C) Paracoccus
D) Pelagibacter

Question 19

Based on oxygen requirements and metabolic strategies, you would most likely isolate an epsilonproteobacterium from

A) anoxic and sulfate-rich waters.
B) a plantʹs rhizosphere.
C) sulfate-rich anoxic-oxic interfaces.
D) sulfide-rich soils.

Question 20

Isolating a bacterium of the ________ class would be of high impact due to it only having one cultured representative.

A) Alphaproteobacteria
B) Betaproteobacteria
C) Epsilonproteobacteria
D) Zetaproteobacteria

Question 21

Campylobacter and Helicobacter are two genera within the ________ class of Proteobacteria.

A) Alphaproteobacteria
B) Betaproteobacteria
C) Deltaproteobacteria
D) Epsilonproteobacteria

Question 22

Staphylococcus aureus is known to cause all of the following diseases EXCEPT

A) acne.
B) arthritis.
C) boils.
D) dental caries.

Question 23

A yogurt, which had ʺcontains live culturesʺ on its label, was transferred onto an acidic carbohydrate-containing medium for selective enrichment. Eventually, isolates of the ________ genus were obtained.

A) Lactobacillus
B) Leuconostoc
C) Peptococcus
D) Streptococcus

Question 24

A moistened swab rubbed onto a personʹs forearm then onto a nutrient agar plate with 7.5% NaCl would most likely result in the isolation of ________ spp.

A) Clostridium
B) Halobacterium
C) Sarcina
D) Staphylococcus

Question 25

The ability to form endospores in bacteria within Bacillales, Clostridiales, and Lactobacillales suggests the genotype/phenotype evolved

A) at least three separate times in these divergent orders.
B) at least once, and horizontal gene transfer among relatives explains its presence in other orders.
C) only once in an ancestor to these three orders, due to the high number of genes required.
D) either at least once and horizontal gene transfer among relatives occurred or once in a common ancestor.

Question 26

Mycoplasmas lack cell walls, thus

A) they have a larger cytoplasmic volume.
B) frequently exist as obligate symbionts.
C) they have a higher sensitivity to osmotic lysis.
D) they are unable to survive conditions under which protoplasts lyse.

Question 27

Which group in Bacteria lacks cell walls?

A) Corynebacterium
B) Mycoplasma
C) Sporosarcina
D) Tenericutes

Question 28

The order Lactobacillales within Firmicutes are also called the lactic acid bacteria, because these bacteria

A) can aerobically catabolize lactic acid.
B) can ferment lactate.
C) produce lactate.
D) uniquely require lactic acid as a precursor for cell wall biosynthesis.

Question 29

Due to the presence of mycolic acids in the cell wall of Mycobacterium spp., the ________ staining procedure can be used as a diagnostic tool to identify this genus.

A) acid-fast
B) DAPI
C) Gram
D) lipo

Question 30

What would most likely result if an exponentially growing culture of Lactobacillus spp. fermenting glucose was accidentally transferred into a highly aerated environment?

A) Aerobic catabolism of glucose would begin rather than aerobic degradation, due to the presence of O₂.
B) Fermentation of glucose would continue, because the cells are insensitive to O₂ despite lacking aerobic metabolism capabilities.
C) The cells would halt their metabolism due to the presence of N₂, which acts as a global repressor of fermentation in this group.
D) The population would die due to the presence of O₂, because it is a strict anaerobe.

Question 31

Snapping division is a hallmark trait of ________ which can be visualized under a microscope by ________.

A) Actinobacteria / two adjacent cells linked, appearing as an M dividing into four
B) Actinobacteria / one cell appearing as a V dividing into two
C) Coryneform bacteria / two adjacent cells linked, appearing as an M dividing into four
D) Coryneform bacteria / one cell appearing as a V dividing into two

Question 32

Which organisms would most likely be isolated from aerobic growth conditions with acetate and a soil sample heated to 80°C for 10 minutes?

A) aerobic or facultative anaerobic acetogens
B) endospore-forming bacteria
C) hyperthermophilic heterotrophic bacteria
D) mycoplasmas

Question 33

Which species does NOT produce endospores?

A) Bacillus cereus
B) Clostridium pasteurianum
C) Listeria monocytogenes
D) Paenibacillus popilliae

Question 34

Which bacterial genus would be best to select for fermenting cabbage to make homemade sauerkraut?

A) Clostridium
B) Lactobacillus
C) Propionibacterium
D) Staphylococcus

Question 35

A gram-negative, nonsporulating rod that is highly motile, oxidase negative, facultatively aerobic, ferments glucose, and urease-positive is likely to be of which genus?

A) Pseudomonas
B) Proteus
C) Lactobacillus
D) Rickettsia

Question 36

Which phenotypic assay could be used to determine whether a new Streptococcus spp. is of the pyogenes or viridans group?

A) catalase assay with H₂O₂
B) hemolytic type after growth on a blood agar plate
C) occurrence of cells being in clusters or as individual cells under a microscope
D) product(s) formed during lactose fermentation

Question 37

Which genus is most easily distinguishable from others below by occurring in cell clusters of 8 or more?

A) Peptostreptococcus
B) Sarcina
C) Staphylococcus
D) Streptococcus

Question 38

Which of the following is LEAST commonly associated with endospore-forming bacteria?

A) They are coccus-shaped organisms.
B) They are primarily soil dwellers.
C) They can survive adverse environmental conditions.
D) They are saprophytic.

Question 39

Which bacillus-shaped genus are primarily intracellular parasites of arthropods such as crustaceans and insects?

A) Coxiella
B) Klebsiella
C) Roseospirillum
D) Wolbachia

Question 40

The need for additional supplementation of ________ make developing growth media to culture mycoplasmas especially challenging.

A) unsaturated fatty acids
B) sterols
C) vitamins
D) unsaturated fatty acids, sterols, and vitamins

Question 41

Many Listeria spp. grow well at cold temperatures, so although refrigeration is excellent at preventing growth of most other pathogens, it is NOT very useful at minimizing growth of contaminated foods.

Question 42

Which bacterial genus is LEAST related to the others listed?

A) Actinomyces
B) Mycobacterium
C) Nocardia
D) Streptomyces

Question 43

Which of the following is NOT a trait of the Planctomycetes?

A) undergo budding cell division
B) have intracellular compartmentalization
C) lack peptidoglycan
D) undergo plant symbiosis

Question 44

Despite ether-linked lipids being a hallmark of the Archaea, the thermophilic sulfate-reducing bacteria in ________ also contain ether-linked lipids, which suggests they may be more closely related to Archaea than many other groups in Bacteria.

A) Aquifex
B) Thermodesulfobacterium
C) Thermus
D) Verrucomicrobium

Question 45

To subgroup the lactic acid bacteria, which are incapable of aerobic degradation and only do fermentation, identifying products formed is a useful way to distinguish homofermentative versus heterofermentative lactic acid bacteria.

Question 46

Sulfur metabolism is a common trait in Deltaproteobacteria.

Question 47

The enteric bacteria are a group classified within Proteobacteria that cause disease in animals.

Question 48

Which structural feature is common in BOTH Planctomycetes and Verrucomicrobia but RARELY found in bacteria outside these two phyla?

A) intracellular compartmentalization
B) prosthecae appendages
C) sheathlike toga cell envelopes
D) tubulins

Question 49

Many gammaproteobacteria members are obligate intracellular symbionts of eukaryotes, which also enables many to become human pathogens.

Question 50

Betaproteobacteria is a functionally diverse group that primarily uses anaerobic metabolisms.

Question 51

Bacteria in the phylum ________ occur as elementary or reticulate bodies depending on their life cycle stage, are obligate intracellular parasites, and also have relatively small genomes.

A) Bacteroidetes
B) Chlamydiae
C) Planctomycetes
D) Rickettsia

Question 52

Members of the ________ are the most abundant bacteria present in the large intestine of humans and contain unusual ________ in their cell membranes.

A) Bacteroides / glycerolipids
B) Bacteroides / sphingolipids
C) Sphingobium / glycerolipids
D) Sphingobium / sphingolipids

Question 53

The ________ produce over 500 characterized antibiotics.

A) Bacteroidetes
B) mycobacteria
C) pseudomonads
D) streptomycetes

Question 54

Rhodobacter and Roseobacter are two genera with a common ancestor in Alphaproteobacteria.

Question 55

A soil sample was diluted into a nutrient broth, then spread onto a plate and grown for one week at room temperature. Several colonies appeared dusty or fuzzy and yet were identified as bacteria-not as fungi. Which genus do these isolates likely belong in?

A) Actinomyces
B) Mycobacterium
C) Nocardia
D) Streptomyces

Question 56

The most metabolically diverse phylum of Bacteria known to date is the Proteobacteria.

Question 57

Members of the ________ are particularly abundant in the oceans, chemoorganotrophic, rarely pathogenic, and often produce pigments when grown on complex media.

A) Clostridiales
B) Flavobacteriales
C) Pelagibacterales
D) Rhizobiales

Question 58

Pseudomonads are aerobic, gram-positive, polar flagellated, bacillus-shaped cells.

Question 59

Agrobacterium tumefaciens can form root nodules in plants and can mate with bacteria, which makes it an excellent host organism for genetic transformations among different domains of life.

Question 60

Due to the genetic similarities of non-pathogenic and pathogenic enterics, phenotypic assays are often performed in favor over taxonomy-based sequencing/probing to distinguish pathogens from non-pathogens.

Question 61

Even to a well-trained microbiologist, isolates of Streptomyces when grown on a nutrient agar plate can appear as though they are fungi. Describe key similarities of how these two unrelated groups can so easily be mistaken for each other, and then propose methods to conclusively distinguish between them.

Question 62

Except that they are not produced in the cytoplasm, conidia produced by Streptomyces spp. are chemically quite similar in composition to endospores produced by Bacillus spp.

Question 63

Due to the slow and varied growth rates, mycobacteria are commonly grouped into either slow growing or very slow growing, which has consequences on the growth medium selected for culturing.

Question 64

Select a group within Bacteria that has rare cell morphology observable with a microscope. Describe the appearance, the group that it corresponds to, and another group that would certainly be ruled out when observing this type of cell morphology.

Question 65

Explain how the enteric bacteria can be differentiated by the type and proportion of fermentation products produced by the anaerobic fermentation of glucose.

Question 66

During stationary phase, group members of Serratia produce prodigiosins that contain pyrrole. Considering its structural relatedness to other pyrrole-containing molecules of known function (e.g., chlorophylls, bacteriochlorophylls, porphyrins), propose a potential ecological role for these compounds in soil where they are involved in something other than photosynthesis.

Question 67

When looking under a transmission electron microscope, you observe pirellulosome in a bacterium. This bacterium likely belongs to the Planctomycetes.

Question 68

Considering the evolution of Bacteria, the criteria used for taxonomy, and the genetic requirements for individual metabolic pathways, explain how it is unlikely to observe three genera of the same family where one genus has strict anaerobes that degrade only small aromatics, another genus degrades large molecular weight sugars aerobically, and a third is a photoautotroph.

Question 69

Deinococcus radiodurans is capable of withstanding especially high levels of radiation, and the carotenoids they produce enhance this resistance.

Question 70

Antibiotics that disrupt or halt cell wall biosynthesis are actually ineffective at harming growth of mycoplasmas.

Question 71

Thermotoga species are hyperthermophiles and appear relatively closely related to Archaea in comparison to other bacteria such as Salmonella.

Question 72

Some species in the genus Acidobacteria are classified in Bacteria while others are considered Archaea.

Question 73

The hypothesis that H₂ was a key electron donor for energy metabolism in primitive organisms is supported by it being such a common trophic strategy in Aquificae.

Question 74

Compare and contrast the human pathogens and non-pathogens in Clostridium. Propose a reason for why this differentiation is challenging to assay in the laboratory (NOT on living eukaryotic animal models).

Question 75

Chlamydiae are most commonly transmitted throughout environments by insects.

Question 76

Which group of bacteria is most famous for their diversity of antibiotics produced? What could be an ecological role of antibiotic production by bacteria when the antibiotics are not produced at a sufficiently high level to be lethal?

Question 77

Cytophaga columnaris causes columnaris (or ʺcottonmouthʺ) disease in fish such as salmon. Based on its taxonomic group, predict some of the activities this bacterium has during infection of fish. Also mention one related taxon that likely has some of the same functions and another taxon that does not.

Question 78

Simple staining and microscopy could easily distinguish the different taxa intermixed within a community of Sarcina, Staphylococcus, and coryneform bacteria.

Question 79

Some Streptomyces spp. can biosynthesize several chemically unrelated structures that act as different antibiotics.

Question 80

Proteobacteria members thrive in soils and occur at high concentrations as well. Other bacterial taxa are considered much less diverse in terms of their metabolic capabilities. Due to the role isolation has in discovering metabolic pathways, consider how obtaining hundreds of new isolates from a less studied phylum might change our views on metabolic diversity. Predict how the results of discovering another highly metabolically diverse group might be handled in terms of taxonomic assignment.