Lab Quiz 3 Flashcards
(55 cards)
1
Q
purpose of oxidation requirement test
A
determine oxidation requirement of organism
2
Q
OR: purpose of sodium throglycollate
A
combine with oxygen to reduce concentration
3
Q
OR test: purpose of agar
A
Increase thickness of media to prevent diffusion of oxygen in media
4
Q
OR test: purpose of resazurin
A
indicate presence of oxygen in tube. pink with oxygen, clear without oxygen present
5
Q
define and describe obligate aerobe
A
- organism requires oxygen
- grown on top of media
6
Q
define and describe microaerophile
A
- organism requires reduced concentration of oxygen
- grown above middle of agar
7
Q
define and describe aerotolerant anaerobe
A
- grows equally well with or without oxygen
- grown all throughout media
8
Q
define and describe facultative anaerobe
A
- can grow with or without oxygen but prefers aerobic conditions
- grow all throughout media but more at the top
9
Q
obligate anaerobe
A
- can not grow in the presence of oxygen
- grows at the bottom of media
10
Q
purpose of anaerobic bag test
A
determine if organism can grow in complete anaerobic conditions
11
Q
indicator for bag test
A
methylene blue indicator strip. blue with oxygen and colorless without oxygen
12
Q
reaction of anaerobic bag test
A
2H2 + O2 = 2H2O
13
Q
Gelatin Hydrolysis test
A
- substrate: gelatin
- enzyme: gelatinase
- product: amino acids
14
Q
+ gelatin hydrolysis test
A
- liquified agar deep after cooling
- gelatinase produced which broke down gelatin into amino acids and automatically liquified media
15
Q
(-) gelatin hydrolysis test
A
- solid agar deep after cooling
- gelatinase not produced and no amino acids form. media remains solid
16
Q
why is it necessary to refrigerate gelatin hydrolysis after incubation
A
to prevent gelatin from spontaneously liquifying after incubation
17
Q
urease test
A
- substrate: H2O and Urea
- enzyme: Urease
- products: ammonia and CO2
18
Q
(+) Urease test
A
- hot pink broth
- urease produced and breaks down urea into ammonia and CO2 which increases pH and phenol red changes from yellow to pink
19
Q
(-) urease test
A
- yellow broth
- urease not produced. pH remains at 6.8 and phenol red does not change
20
Q
urease indicator
A
- phenol red pH indicator
- yellow at 6.8, hot pink >8.4
21
Q
SIM Test: 3 test done
A
- H2S
- Indole
- Motility
22
Q
H2S test
A
- substrate: cysteine
- enzyme: cysteine desulfurase
- products: H2S and pyruvic acid
- H2S + ferrous sulfate = black ferric sulfide
23
Q
indicator H2S test
A
ferrous sulfate
24
Q
(+) H2S test
A
- black agar deep
- cysteine desulfurase produced which creates H2S that combines with ferrous sulfate in media to produce black ferric sulfide
25
(-) test
- yellow agar deep
- enzyme not produced, no H2S to combine with ferrous sulfate
26
Indole Test
- substrate: tryptophan
- enzyme: tryotophanase
- products: indole + Pyruvic acid
27
(+) indole test
- pink layer on top of agar deep
- organism produces tryptophanase and indole and purivic acid produced. indole detected using Kovacs reagent
28
(-) indole test
- yellow layer on top of agar deep
- enzyme not produced. tryptophan not hydrolysis to indole. indole reagent remains yellow
29
indole reagent
- kovacs reagent
30
Motility Test
- (+) test: growth diffusion away from stab line of inoculation
- (-) test: growth restricted to stab line of inoculation
31
Litmus Milk Test Substrates
lactose sugar and milk proteins
32
LM test: Acids
- pink opaque media
- organism uses lactose and acids are produced. pH decreases and litmus turns pink. Opaque since large milk proteins still present
33
LM test: Acids with reduction
- pink opaque media with white band at the bottom of tube
- organism uses lactose which produces acids. pH decreases and litmus turns pink. excess acid production reduced litmus and turns white. opaque media since milk proteins still present
34
LM test: Alkaline reaction
- purple opaque media
- organism uses milk proteins which are partially broken down. slight change in consistency and media
35
LM test: Peptonization
- deep purple/blue clear media
- organism uses milk proteins which are completely hydrolyzed to amino acids. ammonia produced from amino acids which increases pH. litmus turns deep purple/blue. clear media because proteins completely broken down.
36
Litmus Milk Test indicators
- litmus pH and oxidation-reduction indicator
37
(+) Motility Test
- growth dispersion from stab line, cloudy appearance
- organism is motile and was able to move away from line
38
(-) Motility Test
- broth restricted to stab line
- organism not motile, growth only seen along stab line
39
indicator used to determine results easier
- tetrazolium red indicator
40
Microbes in food: method used
- standard plate count
41
what is involved in a standard plate count and what does it determine
- serial dilutions of food/liquid sample in sterile water banks
- determine number of viable bacteria per mL of food sample
42
why is the standard plate count important for food, water, and milk industries
it is part of their quality control
43
calculation for organisms per ml or gram
number of colonies x final dilution factor
44
why is a plate with 25-250 colonies needed
greater than 250 is too many to count. less than 25 will cause unreliable and inaccurate results
45
Define Abstract
brief summary of experimentation. provides an over view of your work and the results obtained
46
components of abstract
- background info
- hypothesis/prediction
- testing method used
- results
47
advantage of abstract
not having to explain methods used in detail
48
Throat culture: media used
5% sheeps blood agar
49
5% sheeps blood agar
- NOT selective media
- differential media: 3 types of colonies based on hemolysis
50
TC: tests used
gram stain and catalase test
51
what test differentiates staphylococcus from streptococcus
catalase test
52
define hemolysis
destruction of RBCs
53
Aloha hemolysis
- partially lyse RBCs
- green zone surrounding colonies
54
Beta Hemolysis
- complete lysis of RBCs
- clear zone surrounding colony
55
Gamma Hemolysis
- do not produce hemolysins
- red agar surrounding colonies
