MLSP: VULTURE MEDIA PREPARATION (LAB) Flashcards
Solid, liquid or semi-solid [gelatinous in appearance] designed to support the growth of microorganisms
CULTURE MEDIA
(15-20 ml; solid media)
Petri plate
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.
Solid
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
Agar
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]
LIQUID OR BROTH
LIQUID OR BROTH
turbidity
Growth
LIQUID OR BROTH
clarity [if there’s no change in clarity, there is no growth]
No Growth
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]
SEMI-SOLID
- 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]
SEMI-SOLID
Contains specific nutrients required for growth of particular bacterial pathogens
ENRICHMENT MEDIA
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
SELECTIVE MEDIA
Enriched usually by adding blood, or eggs
- Already dehydrated, and already mixed with the mixture
ENRICHED MEDIUM
Contain nutrients to support growth of most
nonfastidious organisms without giving any particular organism a growth advantage
SUPPORTIVE OR NONSELECTIVE MEDIUM
Used to distinguish them from other bacteria growing on the same agar plate
- Differentiate different types of bacteria based on appearance
DIFFERENTIAL MEDIUM
CULTURE MEDIA PREPARATION STEPS
Tube media
- Weigh
- Dissolve
- Dispense
- Sterilize
CULTURE MEDIA PREPARATION STEPS
Plated media (solid)
- Weight
- Dissolve
- Sterilize [sterilize first before dispensing]
- Dispense [in sterile conditions]
The process of rendering a medium or material free of all forms of life
- Giant batch (10-20 tubes)
STERILIZATION
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
AUTOCLAVING
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
ULTRAVIOLET (UV) RADIATION
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
ETHYLENE OXIDE
