Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICR 203 > lecture 5 - biochem tests > Flashcards

lecture 5 - biochem tests Flashcards

1
Q

biochem tests are used to differentiate

A

enterobacteriaceae or now refered to as order:
Enterobacterales

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why do we do biochem tests?

A
  • detect what substrate it uses to produce energy
  • different pathwats
  • acidic or basic byproducts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

acid fushin (andrades)

A

acid - pink
basic - pale yellow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

bromcrescol green

A

acid: yellow
basic: blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

bromcresol purple

A

acid: yellow
basic: purple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

bromthymol blue

A

acid: yellow
basic: blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

methyl red

A

acid: red
basic: yellow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

neutral red

A

acid: red
basic: yellow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

phenol red

A

acid: yellow
basic: red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

cresol red

A

acid: yellow
basic: red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

the main sources of energy for bacterial growth are:

A

carbohydrates + peptones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are peptones?

A

smaller denatured proteins that are easier to use because small and readily available

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

carbohydrates produce:

A

acid in anaerobic, CO2, or aerobic conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

peptones produce:

A

alkaline in aerobic only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

hugh & leifsons O/F test

A
  • differentiates glucose oxidizer (carb - acid) or fermenter (peptone - alkaline)
  • lots of glucose
  • little peptone
  • bromthymol blue indicator
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

H&L O/F Test pos/neg

A

F: Enterobacterales
O: Neiseseria, Pseudomonas, Stentrophomonas, Burkholderia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Carbohydrate Fermentation Test:

A
  • determines ability to ferment diff. sugars to form acids
  • basic media, 1% of each sugar. phenol red
  • also has durham tube for gas production
  • if pos, turns yellow (acid formed)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

glucose is ______ for all enterobactererales

A

yellow!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

glucose –> pyruvic acid –>

A

mixed acid path - acidic byproduct

OR

neutral products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

methyl red test

A
  • inoculate MRVP
  • add methyl red
  • red = mixed acid
  • no change = ?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Voges-Proskauer Test

A
  • inoculate MRVP broth
  • add a-naphthol & 40% KOH, shake gently, observe for 10-15min
  • red = acetoin (neutral path)
  • no change = no acetoin produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

MRVP results

A

most members of Enterobacterales give opposite rxns
- E.coli = MR (+) & VP (-)
- Klebsiella, Serratia, Enterobacter = MR(-) & VP (-)
- Proteus mirabilis = MR(+) & VP (+)

23
Q

TSI Agar

A
  • gives info about:
  1. Fermentation of glucose (0.1%), lactose (1%), sucrose (1%)
  2. Production of CO2 gas during ferm. (CO2 - aerogenic, none - anaerogenic)
  3. Production of H2S gas –> black
24
Q

why is glucose in such a small percent?

A

looking at organisms that all ferment glucose so you do not need very much

25
Q

TSI Media

A
  • peptone (basic growth media)
  • glucose, lactose, sucrose
  • phenol red
  • sodium thiosulphate and ferrous sulfate for H2S
26
Q

how do you read a TSI agar test?

A

top to bottom

27
Q

producton of H2S gas

A

some microbes can liberate colourless H2S gas from:
- sulphur containing amino acids (cystein/methionine)

sodium thiosulphate –> ferrous sulphate + colourless H2S gas –> ferrous sulphide (black ppt)

28
Q

if you see black ppt (H2S), do we call it Alk or Ac underneath?

A

always acid

29
Q

other H2S indicators include:

A
  • ferrous citrate (most common)
  • ferric ammonium citrate
  • lead acetate
30
Q

why is incubation time critical for TSI?

A
  • do not want all of the glucose consumed and then have the organism turn to using peptone
31
Q

why do caps need to be loose for TSI test?

A

allow CO2 to escape to maintain aerobic bc no peptone use with w/o O2

32
Q

Indole Test

A
  • organism produce tryptophanase, hydrolize tryptophan to produce INDOLE, pyruvic acid, NH3
  • can be detected w/ Kovacs, p-aminobenzaldehyde or cinnamaldehyde reagent
  • red in alcohol layer = pos for indole
33
Q

Indole Test - pos organisms

A
  • E.coli
  • Klebsiella oxytoca
  • Proteus spp. (except mirabilis & penneri)
34
Q

Urease Test

A
  • ability to split urea –> CO2 and NH3 (alkaline byprod.)
35
Q

Urea Medium

A
  • peptone
  • glucose
  • urea
  • phenol red
36
Q

Urease Test Results

A

Rapid Pos - Proteus mirabilis
Delayed Pos - Klebsiella pneumoniae
Neg - Eschericia coli

37
Q

Decarboxylase Test

A
  • some organisms can decarboxylate AA to produce amine and CO2
  • yellow = AA was not decarboxylated
  • purple/turbid = AA was decarboxylated
38
Q

Decarboxylase Media

A
  • Moeller’s Medium
  • basic medium
  • glucose
  • amino acid
  • pH indicator (bromcresol purple and cresol red)
  • acid overlay * very important*
39
Q

what amino acids get decarboxylated during the decarboxylase test?

A

Lysine –> Cadaverine
Ornithine –> Putrescine
Arginine –> Citrulline

all + CO2

40
Q

phenylalanine deaminase (PPA/PDA) & tryptophasn deaminase (TDA) tests + reactions

A
  • some organisms can remove amino group from phenylalanine or tryptophan

Phenyl –> phenylpyruvic acid + NH3 / Tryptophan –> indolepyruvic acid

add indicator (ferric chloride) –> dark green or brown

41
Q

PDA/TDA is useful for differentiating:

A

urease positive organisms

  • proteus, providencia & morganella
42
Q

citrate test

A
  • some org. use sodium citrate as sole source of carbon for growth
  • citrate + ammonium phosphate –> ammonia + ammonium hydroxide
  • alkaline –> blue
43
Q

Citrate Test Media/Conditions

A
  • sodium citrate
    -ammonium phosphate
  • bromthymol blue
  • O2 required
  • light inoculum (not too much or false pos bc feed off each other)
  • some org. dont produce colour change but have growth, still negative
44
Q

Citrate Test Results

A

Pos: Salmonella, Citrobacter, Klebsiella, Enterobacter, Serratia & Providencia species

Neg: Escherichia, Shigella, Morganella, Yersinia

Variable: Proteus species

45
Q

Nitrate Reductase Test

A
  • if org produces nitrate reducate, will reduce nitrate (NO3) to nitrite (NO2)
  • then reacts w/ added sulfanilic acid + a-napthylamine to form red dye (rxn 1)
  • some reduce nitrite to nitrogen gas (N2) (rxn 2), wont react w reagents from rxn 1
  • add zinc to determine if nitrate was not reduce, so zinc will reduce nitrate to nitrite + reagents = red

OR

  • nitrate was reduced to N2, no colour will develop
  • can detect nitrogen gas w/ durham tube
46
Q

ONPG test

A
  • o-nitrophenyl-B-D-galactopyranoside –> galactose + O-nitrophenol (ignores permease)
  • ANY yellow = pos
47
Q

Gelatinase Test

A
  • uses gelatin w/gelatinase, cover charcoal
  • if organism can break down gelatin, it is pos bc charcoal released
48
Q

Gelatinase Test Results

A

pos: proteus & serratia species AND Pseudomonas fluorescens

Neg: Pseudomonas putida

49
Q

Motility Test

A
  • stab, if cloudy then motive, can have pH indicator
50
Q

a quicker way to witness bacterial motility is

A

wet preparation

51
Q

what is a notable non-motile bacteria?

A

bacillus anthracis

52
Q

Motility Results

A

Non-motile Enterobacterales
- Klebsiella & Shigella

Yersinia enterocolitica
- motile at 25C but not 35C

Listeria spp. (GPB)
- umbrella motility in tube
- tumbling in wet mount

Bacillus anthracis (GPB)
- NON MOTILE!

53
Q

MUG Test

A
  • for E.coli O157:H7 stool pathogen
  • produces toxin and read under UV light
  • pos - glows
  • neg - no glow (E.coli O157:H7)
  • 4-methylumbelliferyl-B-D-glucoronide –> (B-glucoronidase) –> 4-methylumbelliferone

MICR 203 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions