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Bio 251 > Lab 9 > Flashcards

Lab 9 Flashcards

1
Q

What are the differential media used to detect enzymatic activity in the lab?

A

Triple sugar Iron
Sulfide-Indole-Motility
Simmons Citrate
Urea agar

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2
Q

The medium contains three different sugars (glucose, sucrose, lactose) and differentiates bacteria based
on the fermentation of these sugars. It also contains ferrous sulfate to detect sulfur reduction.

A

Triple Sugar Iron agar (TSI)

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3
Q

What is the indicator for TSI agar to monitor pH

A

Phenol red

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4
Q

What color does the TSI agar show for acidic and for alkaline?

A

Yellow in acidic and pink-red in

alkaline

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5
Q

What is important about the slanted agar for TSI agar?

A

We can observe fermentation and aerobic respiration in the same agar

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6
Q

When bacteria ferment sugars it produces?

Color?

A

acid byproducts and turn it YELLOW

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7
Q

When bacteria ferment glucose where can you observe that in the tube?
What about Sucrose and lactose?

A

Glucose in the BUTT / does not require oxygen

Sucrose & lactose on the slant / do require oxygen

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8
Q

Many bacteria produce Co2 gas during fermentation and this can be observed by

A

Cracks in the agar

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9
Q

after depleting the glucose, the bacteria used the amino acids for food, what is this called?
What does it produce and what does it do to pH?

A

Peptonization

Ammonia and makes pH more alkaline

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10
Q

In triple sugar agar if the butt and slant are both red what does it mean?
What is it called?

A

Bacteria did not ferment any of the sugars and only peptones were used
Bacteria were not Enterobacteriaceae or alkaline
reversion/conversion occurred.

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11
Q

In triple sugar agar, if the butt is red but the slant is yellow what does that mean?

A

The bacteria fermented glucose but were not able to use sucrose or lactose

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12
Q

occurs when the bacteria initially rapidly ferment all the sugars,
turning the media yellow. After depleting the sugars, the bacteria then use the amino acids for
food and the media turns red.

A

Alkaline reversion/conversion

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13
Q

In TSI agar, what does it mean if bacteria produced H2S gas and show black?

A

Bacteria reduced sulfate for anaerobic respiration

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14
Q

what media tests for media that tests for sulfur reduction, tryptophan metabolism, and motility.

A

Sulfide-Indole-Motility (SIM) Medium

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15
Q

What does it mean if SIM media turns black?

A

bacteria can remove sulfur from cysteine or reduce sulfur directly. This process produces H2S
gas in the medium.

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16
Q

If bacteria did not reduce sulfure in SIM media what color will it be?

A

Clear

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17
Q

What is the enzyme that which hydrolyzes the amino acid, tryptophan.

A

tryptophanase

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18
Q

When tryptophan is hydrolyzed what is produced?

A

indole and pyruvate.

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19
Q

What is added to SIM agar to detect indole?

A

Kovac’s reagent

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20
Q

Kovac’s reagent contains dimethylaminobenzaldehyde

(DMABA), which reacts with indole to form

A

rosindole (a cherry red compound)

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21
Q

In SIM media if its cherry red it means?

A

its positive for indole

22
Q

In SIM media, what does it mean if you see cloudiness from the stab line?

A

Bacteria are motile

23
Q

agar contains sodium citrate as the only available carbon source.

A

Citric Acid Metabolism:

24
Q

Enzyme that can use sodium citrate and nitrogen to produce ammonia, which will change the pH in the agar to an alkaline pH (above 7).

25
Q

In Simmons Citrate agar What color indicates positive for citase activity?
What color for negative?

A

Blue - positive

Green - negative

26
Q

What is the pH indicator for Simmons citrate agar?

A

bromthymol blue.

27
Q

What does urea agar contain>

A

gar contains urea, peptones, glucose, and phenol red (indicator).

28
Q

What enzyme can hydrolyze certain amino acids and urea to ammonia and
carbon dioxide.

29
Q

What does it mean when Urea agar is bright pink?

A

bacteria have urease enzyme and hydrolyze urea to ammonia.

30
Q

Public drinking water is tested and treated to ensure that the water is safe to drink and free from contamination with microbes.

31
Q

What are the pathogens that may be present in drinking water?

A

Parasites: Cryptosporidium, Giardia
Viruses: Norovirus
Bacteria: Salmonella, Shigella, E. coli, Vibrio cholera, Campylobacter, Leptospira

32
Q

What is one contamination of water that is resistant to chlorine and can cause gastrointestinal outbreaks in US?

A

Fecal contamination

33
Q

What are Gram-negative bacillus (rod-shaped) that are facultative
anaerobes, ferment lactose producing acid and gas, and only live in the
gastrointestinal tract of animals.

A

Coliform bacteria

34
Q

Coliforms include species of

A

Escherichia, Klebsiella, Enterobacter and more

35
Q

You can screen water using selective-differential media. This media select for growth of? and inhibits?

A

Growth Gram negative. Inhibit gram positive

36
Q

The selective diffierential media are

A
  1. Rapid’E.coli 2 Agar
  2. Eosin Methylene Blue
  3. Hektoen Enteric Agar
  4. MacConkey Agar
37
Q

Eosin Methylene Blue contains what 2 dyes>

A

eosin Y and methylene blue.
*The dyes inhibit the growth of Gram-positive bacteria and act as an indicator that reacts with
the acid produced by lactose fermenters.

38
Q

Eosin Methylene Blue shows coliforms positive as what color? and non coliforms as what color?

A

Coliforms positive - Metalic green and media pink-dark purple
Coliform negative - agar is red

39
Q

Hektoen Enteric Agar (HEA) contains what to inhibit growth of most gram positive bacteria and what 3 sugars?

A

Bile salts
lactose,
sucrose, and salicin

40
Q

What is Hektoen Enteric Agar used to diffieriente

A

resence of coliforms and Salmonella and Shigella from other enterics

41
Q

In Hektoen what color will show positive for fermination?

Negative?

A

Positive = Yellow - pinkish orange

Negative - Blue green

42
Q

If Heltoen Enteric agar contains sodium thiosulfate (sulfur) and ferric ammonium citrate, it will turn?

43
Q

MacConkey Agar (MCA) contains & why

A

Bile salts and chrystal violet to inhibit gram positive growth

44
Q

MacConkey Agar (MCA) contains what indicator?

A

neutral red indicator

45
Q

MacConkey Agar (MCA) Turns what color if fermentation occurs? If negative?

A

Positive - pink

Negative - colorless

46
Q

What does Rapid’E. coli 2 Agar relies on simultaneous detection of what 2 enzymes

A

-D-Galactosidase (GAL), and β-D-Glucuronidase (GLUC).

47
Q

Rapid’E. coli 2 Agar is positive what color? Negative?>

A

Positive - blue

Negative - pink

48
Q

viruses that infect

and replicate inside bacteria

A

Bacteriophage

49
Q

This dormant viral DNA is known as

50
Q

What occurs when the phage makes a

mistake

A

Transduction

Bio 251 (17 decks)

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