Lab (Post-Midterm) Flashcards

1
Q

what does SCOBY stand for?

A

symbiotic culture of bacteria and yeast

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2
Q

what agars were used with kombucha?

A

SD and nutrient agar

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3
Q

what does SD agar test for?

is it acidic or basic?

A

yeast

acidic medium

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4
Q

what does nutrient agar test for?

is it acidic or basic?

A

bacteria

basic medium

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5
Q

what are main LAB in kefir?

what are other MOs?

A

lactobacilli and lactococci

AAB and yeast

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6
Q

what media are used in kefir lab?

what does each one test for?

A

HHD: homo or heterofermentative LAB

MRS: presence of LAB

OGYE: yeast

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7
Q

in OGYE, what is the selective agent

A

oxytetracycline

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8
Q

what is the predominant organism of yogurt starter cultures?

A

LAB

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9
Q

what biochemical rxns occur in yogurt fermentation?

A

CHO –> lactic acid

caseins –> to peptides –> free AA

milk fat –> free FA

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10
Q

what agar is used in yogurt lab?

A

HHD

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11
Q

in HHD agar medium, what is the fermentable CHO?

what is the pH indicator?

A

fructose

bromo cresol green

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12
Q

in HHD again, what does heterofermentative LAB producce? what does homo LAB produce?

A

hetero: Co2, lactic acid, acetic aid, ethanol, mannitol
homo: produces only lactic

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13
Q

in yogurt, what color does homofermentative LAB produce?

A

yellow

due to producing lactic acid from fructose

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14
Q

in yogurt, what color does heterofermentative LAB produce?

A

varies in color depending on medium used

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15
Q

on HHD agar, what color does homofermentative LAB produce?

A

bluish-green colonies

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16
Q

on HHD agar, what color does heterofermentative LAB produce?

17
Q

what media were used in maple syrup lab?

A

nutrient agar

Sabouraud dextrose

18
Q

what does SD agar test for in maple syrup lab?

19
Q

what kind of maple syrup is more susceptible to fungi growth?

A

packaged maple syrup not sufficiently heated before sealing

or maple syrup stored for a long time after opening

20
Q

describe the kerby-bauer method in the antibiotics lab

A
  • diskcs with antimicrobial agents are placed on bacterial cultures on Mueller Hinton agar plates
  • after incubation, zones of bacterial growth inhibition around the disk are measured and compared with standard zone size
21
Q

what are the two media used in the antibiotics lab

A

muller hinton

TSA = tryptic soy agar

22
Q

describe the muller hinton agar

A
  • non-selective and non-differential
  • many MOs will grow on it
  • contains starch (absorbs toxins released from bacteria so they dont interfere with the antibiotics)
  • “loose” agar: allows for diffusion of antibiotics through the media to give easier zone inhibition measurements
23
Q

describe TSA

A

tryptic soy agar

  • not selective or differential
  • composed of digests of soybean meal and casein
  • soy and casein peptones supply N, which makes it highly nutritious
  • contains NaCl to maintain osmotic equilibrium
24
Q

in spoilage due to underprocessing of canned food, what MOs will be present?

A

heat tolerant MOs

25
in spoilage due to can leakage of canned food, what MOs will be present?
hetergeneous low heat resistance
26
what agars are used in the spoilage food lab? what does each test for?
tomato serum media: lactobacillus species nutrient agar: general MOs plate count agar: bacterial growth
27
what broths are used in the spoilage food lab?
dextrose tryptone broth: MOs which produce acid from dextrose are detected by color change (purple to yellow) liver broth: to examine saccharolytic or putrefactice mesophilic and thermophilic anaerobes. Bacterial growth produces increase in turbidity and/or gas