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Flashcards in Lab Practical 2 Deck (70):
1

FTM

fluid thioglycollate media

2

what does thioglycollate do

reacts with oxygen to remove it to create an anaerobic environment

3

What does red indicate in thyioglycollate media?

Resazurin is added to FTM, if it turns red/pink it indicates the presence of oxygen

4

Brewer's agar

a type of agar with methylene blue added.
Blue color indicates specimen has been in oxygenated environment. If placed in gaspak jar, it should turn clear if in anaerobic environment

5

GasPak jar

creates an anaerobic environment - packets are put inside that get rid of oxygen

6

Obligate Aerobes

-Have SOD and catalase
-must have oxygen for metabolism (aerobic respiration) and growth
-Most fungi and protists, some bacteria (Bacillus, Pseudomonas)

7

Facultative Anaerobes

-Usually have SOD and catalase
-“flexible” – can survive with or without oxygen
-Grow best with oxygen (aerobic respiration)
-E. coli, Staphylococcus and Saccharomyces (yeast)

8

Microaerophiles

-Only small amounts of SOD and catalase
-Need small concentrations of oxygen (2-10%) for aerobic respiration
-Large amounts of oxygen are inhibitory
-Found in mucous linings of hollow organs
-Helicobacter pylori

9

Obligate Anaerobes

-Usually lack both SOD and catalase
-Cannot grow if oxygen is present
-No aerobic respiration
-deep mud, lakes, oceans, inside animal bodies
-Clostridium

10

Aerotolerant Anaerobes

- May have SOD, but not catalase
- Indifferent to oxygen
- Do not use oxygen – obligate fermenters
- Streptococcus pyogenes

11

catalase

degrates hydrogen peroxide into oxygen and water

12

superoxide dismutase

converts superoxide ion to oxygen and hydrogen peroxide

13

peroxidase

breaks down hydrogen peroxide to water with the help of NAD+

14

anaerobic respiration

inorganic compounds such as sulfate or nitrates replace oxygen as the terminal electron acceptor

15

results of growth patterns of FTM

Aerobic - grows only on top
Microaerophilic - towards top but not exposed to oxygen
Facultative - throughout media
Anaerobic - in the bottom of media

16

*Add lab 13

*study lab 13

17

Psychrophiles

-cold loving, - 5C to 15C
-Grow in polar and glacial regions

18

Psychrotrophs

-“cold feeding,” 20C to 30C
-do not cause infections in humans
-responsible for spoiling of refrigerated and frozen food

19

Mesophiles

-middle-loving, 25C to 45C
-optimum temperature for human pathogens is around 37C

20

Thermophiles

- heat loving, 45oC to 70oC
-Found in natural hot springs, compost

21

Hyperthermophiles

-extreme heat loving, 70oC +
-usually Archaea, hydrothermal vents

22

Bacteria usually live in what kind of solution

hypotonic
cell wall gives protection from high osmotic pressure

23

what will bacteria do to maintain their environment

-Bacteria will maintain hypotonic environment outside cell
-Pump in K+ or produce extra amino acids

24

Non-tolerant

needs hypotonic environment

25

Halotolerant

- up to 10% NaCl
- can tolerate moderate concentrations of salt
- Staphylococcus on skin

26

Halophiles

- (obligate halophiles)
- require a high level of NaCl
- marine microbes, extreme halophiles are Archaea living in salt lakes

27

Osmophiles

grow in high sugar concentrations

28

Temperature Requirement Classifications (5)

1. Psychrophiles (cold-loving)
Psychrotroph (Cold-feeding)
2. Mesophiles (middle-loving)
3. Thermophiles (heat-loving)
4. Hyperthermophiles

29

Classification using solute concentration (4)

1. Halotolerant
2. Halophilis (obligate halophile)
3. Losmophiles
4. Non-tolerant

30

Oxidation & Fermentation Reactions (4)

1. Sugar fermentation (Ferment Manitol, Glucose, Lactose)
2. MR-VP (Methyl Red - Vogues Proskauer) Test
3. Catalase Production Experiment
4. Citrate Utilization Experiment

31

Sugar fermentation (Ferment Manitol, Glucose, Lactose)

-Durham tube (upside down tube w/in a tube)
*Indicates the presence of gas that was produces as a result of fermentation (+/-)
-Each tube contains a phenol red pH indicator
**Tube begins red:
-NO color change= NO fermentation occurred
-Color changed to yellow= fermentation occurred

32

MR-VP (Methyl Red - Vogues Proskauer) Test

-->Results:
-two tubes (original & new w/ 1 ml of broth) & 2 solutions to add.
-Original tube: add methyl red indicator: Will turn red if pH dropped below 5 (red= mixed acid fermentation occurred)
-Tube w/ 1 ml: add VP solution A (15) & VP solution B (5): If turns PINK/RED = 2,3 butanedial and ethanol fermentation (instead of acid fermentation) occurred.
**always a + MR/- VP or -MR/+ VP result**

33

Catalase Production Experiment

-Uses nutrient agar plate
-->Results: Drop hydrogen peroxide on plate; if bubbling occurs = catalase positive

34

Citrate Utilization Experiment

-Uses Simmons agar slant (starts dark green) - double inoculate; stab with needle, smear slant
-->Positive= Change to blue
-->Negative= remains green

35

Hydrolysis

-refers to bacteria using enzymes to do catabolic chemical reactions.

36

Hydrolysis Experiments

1. Starch Hydrolysis
2. Urea Hydrolysis
3. Tryptophan Hydrolysis

37

Starch Hydrolysis

-experiment determines if bacteria have enzyme called amylase that breaks down starch to sugar.

38

Starch Hydrolysis Results

Results--> Flood starch agar plate with Grams Iodine (IKI), IKI turns starch to a blue or dark color.
*Positive= “zone of clearing” (lighter coloration) around the colonies

39

Urea Hydrolysis

-experiment determines if bacteria have enzyme called urease that breaks down urea into ammonia.

40

Urea Hydrolysis Results

Results--> Tubes contain phenol red pH indicators (nothing added to tube)
*Positive= broth turns red/purple (indicates presence of urea)
*Negative= NO color change

41

Tryptophan Hydrolysis

-experiment determines if bacteria have enzyme called tryptophanase that break down the amino acid tryptophan into indole and pyruvate.

42

Tryptophan Hydrolysis Results

Results--> Add “indole reagent” to tryptophan broth
*Positive= Indole is present (and tryptophan broken down), RED layer will form at top of tube.

43

Kligler’s Iron Agar

-experiment determines if the bacteria are capable of conducting acidic fermentation with glucose and lactose and if they produce hydrogen sulfide gas from amino acid cysteine.

44

Kligler’s Iron Agar Results

Results--> Possible color changes in tube:
*Bottom YELLOW, top REDDISH= glucose used during fermentation
*Entire tube YELLOW= glucose and lactose used during fermentation
*Tube turns BLACK= Amino acid cysteine into pyruvic acid, ammonia, and hydrogen sulfide

45

Diagnostic key

-used to identify unknown bacteria.

46

Dichotomous key

- the key always has two answers for each question asked, determines next question or test.

47

thermal death time

-time required to destroy a population of bacteria at a specific temperature

48

thermal death point

-temperature required to destroy a population of bacteria in 10 minutes

49

the area around the disk (antibiotic or cleanser) with no bacteria

zone of inhibition
- measured in mm

50

Oxygen Requirement Classifications (5)

1. Obligate aerobe
2. Facultate anaerobe
3. Obligate anaerobes
4. Microphile
5. Aerotolerant (Aerotolerant Anaerobe, Obligate Fermenter)

51

0

no colony growth

52

+

1-10 colonies

53

++

11-100 colonies

54

+++

101 - uncountable

55

why is UV light lethal bacteria

It causes mutations, such as thymine dimers

56

Dilution Method Experiment

- toothpicks soaked in bacteria where then soaked in a disinfectant for varying lengths of time and then rinsed and placed in nutrient broth.

57

filter paper disk method

a plate is inoculated and filter paper disks soaked in disinfectant are placed on the plate and incubated. The disinfectant with the greatest zone of inhibition is the most effective.

58

When performing plate counts what dilution is easiest to count

1:10,000,000

59

how to calculate cells/mL

(total # of cells counted in six med squares) x dilution factor x 1000
divided by 0.024

60

How to count squares

counts 6 squares, ignore cells touching upper and left borders of a box, but count the cells found on lower or right borders

61

Only count plates with how many colonies

30 - 300
If the cfus are >300, overcrowding on the plate could have inhibited some cells from growing. If cfus are <30, could involve a sampling error.

62

name of device used to count squares

Naubauer counting chamber

63

Types of direct counts

viable
non-viable

64

viable count

standard count, living organisms

65

non-viable

living & dead cells

66

How are population counts conducted?

A sample can be diluted and cells in sample can be counted with a microscope and Petroff-Hauser chamber.

67

Why are population counts important?

To determine the number of bacteria in a sample.
Ex: A diagnosis of bladder infection depends on a certain threshold level of bacteria present in a urine sample.

68

What is a serial dilution?

Start with culture.
Add 1 mL of sample to 100 mL of sterile water = 1:100
Remove 1 mL of 1:100 sample and add to 100 mL of sterile water = 1:1000
Remove 1 mL of 1:1000 sample and add to 100 mL of sterile water = 1:10,000
Remove 1 mL of 1:10,000 sample and add to 100 mL of sterile water = 1:1,000,000

69

Why are serial dilutions necessary?

-Bacteria cells are diluted to an end point where a single cell divides giving rise to the visible colony on a plate.
-Multiply the number of colonies by the dilution factor to determine the number of bacteria in the original sample.

70

Advantages/disadvantages of SPC

Advantages: SPC determines only viable cells

Disadvantages: Specific conditions and media are used and these factors may exclude certain bacteria.