MLSP: VULTURE MEDIA PREPARATION (LAB)

Question 1

Solid, liquid or semi-solid [gelatinous in appearance] designed to support the growth of microorganisms

Answer 1

CULTURE MEDIA

Question 2

(15-20 ml; solid media)

Answer 2

Petri plate

Question 3

solidifying agent is added (1.5-3% of agar); will
gelatinized once set in a room temperature; while agar is the most used solidifying agent, there are other solidifying agents out there for culture media.

Answer 3

Solid

Question 4

is the most commonly used as solidifying agent
- Melt: ≥95°C
- Resolidify: <50°C
- If you leave the mixture at room temperature, it will solidify
- We use solid medium to detect surface growth of microorganisms

Answer 4

Agar

Question 5

 Dissolved in water
- Culture media that is completely dissolved in water and will never solidify
 Uses:
- Can be used to propagate large numbers of
microorganisms in fermentation studies [one way that bacteria eat; fermentation of carbohydrates to produce by-products]
- For various biochemical tests [which there will be color changes or changes in other properties such as pH]

Answer 5

LIQUID OR BROTH

Question 6

LIQUID OR BROTH

turbidity

Answer 6

Growth

Question 7

LIQUID OR BROTH

clarity [if there’s no change in clarity, there is no growth]

Answer 7

No Growth

Question 8

 Solidify agent is added (<1.5% of agar)
- Has smaller concentration of agar compared to solid [not as dense, so its purpose is to determine bacterial motility]
 Uses:
- Fermentation studies
- In determining bacterial motility [how the bacteria migrates from the area it is introduced]
- Promoting anaerobic growth [the deeper you go, there will be lesser oxygen]

Answer 8

SEMI-SOLID

Question 9

• In the negative, there is a straight line [discolored], so it is negative for motility (the bacteria is non- motile); the growth only occurred at the site of inoculation
• In the positive tube, it is positive for motility
  [fainter but thicker line]

Answer 9

SEMI-SOLID

Question 10

 Contains specific nutrients required for growth of particular bacterial pathogens

Answer 10

ENRICHMENT MEDIA

Question 11

 Favour the growth of a particular bacterium by inhibiting the growth of undesired bacteria band allowing the growth of desired bacteria
- Will only choose a specific type
- Kills off other types of bacteria and will only
promote growth of a certain type
- Good example is the mahogany agar of gram
negative organisms only

Answer 11

SELECTIVE MEDIA

Question 12

 Enriched usually by adding blood, or eggs
- Already dehydrated, and already mixed with the mixture

Answer 12

ENRICHED MEDIUM

Question 13

 Contain nutrients to support growth of most
nonfastidious organisms without giving any particular organism a growth advantage

Answer 13

SUPPORTIVE OR NONSELECTIVE MEDIUM

Question 14

 Used to distinguish them from other bacteria growing on the same agar plate
- Differentiate different types of bacteria based on appearance

Answer 14

DIFFERENTIAL MEDIUM

Question 15

CULTURE MEDIA PREPARATION STEPS
 Tube media

Answer 15

• Weigh
• Dissolve
• Dispense
• Sterilize

Question 16

CULTURE MEDIA PREPARATION STEPS
Plated media (solid)

Answer 16

• Weight
• Dissolve
• Sterilize [sterilize first before dispensing]
• Dispense [in sterile conditions]

Question 17

 The process of rendering a medium or material free of all forms of life
- Giant batch (10-20 tubes)

Answer 17

STERILIZATION

Question 18

THREE BASIC WAYS OF STERILIZATION OF MEDIA
 Exposure to steam at 121°C and 15 lbs of pressure ofm15 minutes or longer, depending on the nature of the item
- Uses steam under pressure
 Microorganisms, even endospores, will not survive longer than about 12 to 13 minutes

Answer 18

AUTOCLAVING

Question 19

THREE BASIC WAYS OF STERILIZATION OF MEDIA

 Around 260nm is quite lethal to many organisms but does not penetrate glass, dirt films, water, and other substances very effectively
- Biosafety cabinet has usually uv lamps attached to it

Answer 19

ULTRAVIOLET (UV) RADIATION

Question 20

THREE BASIC WAYS OF STERILIZATION OF MEDIA

 Both microbicidal and sporicidal and kills by covalentlymattaching to cell proteins
 It is particularly effective sterilizing agent because it rapidly penetrates packing materials, even plastic wraps

Answer 20

ETHYLENE OXIDE