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MICB 3301 Lab > Quiz 3 > Flashcards

Quiz 3 Flashcards

1
Q

Characteristics that make microorganisms ubuitous

A
  • Small size
  • Rapid reproduction
  • Metabolic diversity
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2
Q

Aflatoxins

A

Flat-ringed, planar compounds that can intercalate between bases of DNA and act as mutagens, carcinogenic (from Aspergillus flavus)

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3
Q

Myxobacteria (Myxococcus xanthus)

A

Gram - rod-shaped bacteria, found in soil and plant residue
* Very social, predatory, binary fission
* Flexible cell wall, utilizes gliding motility to “ripple” across a surface
* Forms fruiting bodies from vegetative cells upon starvation, in which dormant myxospores are formed and can germinate in nutrient-rich conditions

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4
Q

Phylum Actinobacteria

A

Aerobic, Gram +, with high GC (“actinomycetes”)
* Produce hyphae and mycelium, which give rise to conidiospores
* Leathery culture formed from aerial (conidiospores) and submerged mycelium
* Ex. Streptomyces

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5
Q

Streptomyces

A

An actinomycete found in the microflora of most soils
* Produces the chemical (geosmin) causing earthy scent of moist soil following rain (petrichor)
* Produces over 10,000 bioactive compounds, serving as major sources of antibiotics

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6
Q

Cyanobacteria

A

Gram - bacteria, perform oxygenic photosynthesis
* Contain chlorophylls

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7
Q

Green and Purple Bacteria

A

Carry out anoxygenic photosynthesis using other reduced compounds as e- sources
* Contain bacteriochlorophylls

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8
Q

Photosynthetic bacteria utilize accessory pigments such as ____ and ____ to optimize light harvesting across the visible spectrum

A

phycobiliproteins, carotenoids

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9
Q

Rhodospirillum rubrum

A

A photosynthetic, purple nonsulfur bacterium
* Observed spiral motility under phase-contrast and darkfield

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10
Q

Winogradsky Column

A

An artificial microbial ecosystem in which microorganisms and nutrients interact over a vertical gradient

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11
Q

Winogradsky column vertical bacteria breakdown

A

Top (high O, low S)
Algae
Cyanobacteria
Sulfur-oxidizing bacteria
Purple non-sulfur bacteria
Purple sulfur bacteria
Green sulfur bacteria
Anaerobic bacteria
Bottom (low O, high S)

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12
Q

By adding chemicals to a minimal medium, it is possible to ____ the growth of interfering microbes, or ____ the growth of the sought-after microbe

A

repress (repressive selection), encourage (enrichment selection)

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13
Q

Differential plating

A

Making isolations of target colonies grown from a repressive/enrichment selection to ascertain the purity of the culture

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14
Q

Escherichia coli

A

Gram - rod, resides in lower intestinal tract
* Motile, no endospores

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15
Q

Enterococcus faecalis

A

Gram + cocci, resides in lower intestinal tract
* Non-motile, no endospores

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16
Q

Staphylococcus (from face swab)

A

Gram + cocci, resides on mammalian skin and in sand or water plants
* Non-motile, no endospores

17
Q

Bacillus

A

Gram + rods, resides in soil
* Motile, produces endospores, isolated via heating

18
Q

Pseudomonas

A

Gram - rods, resides in soil
* Motile, no endospores

19
Q

Azotobacter

A

Gram -, large, ovoid rod-shaped, resides in soil
* Motile/non-motile strains, produces cysts

20
Q

MacConkey’s (MAC) agar and Eosin Methylene Blue (EMB) agar

A
  • Selective and differential media
  • Selects for Gram - bacteria
  • Differentiates bacteria that ferment (pink) and don’t ferment (yellow) lactose
21
Q

DNase Test Agar

A

Establishes a distinction between Serratia and S. aureus (DNase+) from Escherichia and Enterobacter (DNase-), as they produce extracellular deoxyribonucleases indicated with a violet-colored zone

22
Q

Catalase Test

A

Tests for the presence of catalase by the decomposition of hydrogen peroxide (H2O2) to water and O2
* Observed as bubble formation in + (Staphylococcus), no reaction in - (Streptococcus)

23
Q

Oxidase Test

A

Tests for cytochrome oxidase (heme-containing protein used via e- transport in some bacteria)
* Produces purple color if + (Azotobacter, Pseudomonas), colorless if - (Escherichia, Staphylococcus, Enterococcus, Streptococcus)

24
Q

Indole Test

A

Tryptophan can be broken down to indole by some bacteria, detected by Kovac’s reagent to a culture in tryptone broth
* Non-selective, used to separate enterics (E. coli, +) from Enterobacter (indole -)

25
Q

TSI Slant

A

Stabbed butt and streaked up slant
* Bubbles/splitting agar indicate gas
* Black medium indicates H2S
* Yellow = sugar fermented, Red = nonfermented, observe both butt (glucose) and slant (sucrose/lactose)

26
Q

Mannitol Salts Agar (MSA) Plate

A
  • Growth = able to grow in 7.5% salt (selective for Staphylococcus)
  • Yellow = able to ferment mannitol (S. aureus)
  • Red = unable to ferment (S. epidermidis)
27
Q

TTC Deep

A
  • Selective against obligate aerobes
  • Tests for motility
  • Purple color indicates growth
28
Q

Blood Agar Plate (BAP)

A

Tests hemolytic ability
* Beta (clear line, very hemolytic) - E. coli, S. aureus
* Alpha (greenish tint, somewhat hemolytic) - S. pneumoniae
* Gamma (not hemolytic) - S. epidermidis, Enterococcus

29
Q

PAP (Pseudomonas)

A

Growth indicates blue-green pigment (pyocyanin) enhanced

Blue = P. aeruginosa

30
Q

PAF (Pseudomonas)

A
  • Non-selective
  • Growth indicates yellow-green pigment (pyoverdin) enhanced

(Green = P. aeruginosa, Yellow = P. fluorescens)

31
Q

Ashby’s N-Free Plate (Azotobacter)

A

Growth indicates ability to fix atmospheric nitrogen (N2)

32
Q

Bile Esculin Broth (Enterococcus)

A
  • Selective and differential (inhibit Streptococcus)
  • Growth = grows in 4% bile
  • Black precipitate = hydrolyzes esculin to esculitin and glucose
33
Q

Colistin-Naladixic Acid (CNA) Agar Plate

A

Selective for Gram+, differential in measuring hemolytic activity

MICB 3301 Lab (5 decks)

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