F2. Culture Media Preparation Flashcards
Solid, liquid or semi-solid [gelatinous in appearance] designed to support the growth of microorganisms
Culture Media
Where to place?
- Broth tube
- Agar slant
- Agar deep tube
- Agar plate [petri plate]
liquid
3 mL
Broth tube
semi-solid
6 mL
Agar slant
solidified
10 mL
Agar deep tube
solid
15-20 mL
Agar Plate [Petri plate]
Classification of agar according to consistency?
most commonly used as solidifying agent?
- Solid
- Liquid/ Broth
- Semi-solid
Agar
- 1.5-3% of agar
- solidifying agent is added
- will gelatinized once set in a room temperature
- melting point?
- resolidifying point?
Solid
- greater than or equal to 95 degrees celsius
- less than 50 degrees celsius
Uses of solid agar?
- surface growth of microorganisms to observe colony appearance
- pure culture isolations
- storage of culture [long-term storage]
- To observe specific biochemical reactions
completely dissolved in water & will never solidify
Liquid/ Broth
Uses of liquid agar?
- to propagate large numbers of microorganims in fermentation studies.
- For various biochemical tests
there is bacterial growth if it becomes?
turbid
if the clarity is clear after you introduced the bacteria to a specimen then there is?
no bacterial growth
- < 1.5% agar
- Solidify agent is added
- Has smaller concentration of agar compared to solid
- not as dense, do its purpose is to determine bacterial motility
Semi-solid
Uses of semi-solid agar?
- fermentation studies
- determines bacterial motility
- promotes anaerobic growth
Agar classification according to function?
- enrichment media
- selective media
- enriched media
- supportive/ nonselective medium
- differential medium
- Contains specific nutrients
- Used to enhance the growth of particular pathogen from a mixture of organism by using nutrient specificity
ENRICHMENT MEDIA
- Favour the growth of a particular bacterium
- allow growth of desired bacteria
- inhibits the growth of undesired bacteria
SELECTIVE MEDIA
Enriched usually by adding blood or eggs
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
DIFFERENTIAL MEDIUM
Two types of container in culture media:
- Tubed media
- Plated media
- semi-solid/ liquid
- steps for this culture media?
- tubed media
- Weigh, Dissolve, Dispense, Sterilize
- solid
- steps for this culture media?
- plated media
- Weigh, Dissolve, Sterilized, Dispense
- process of rendering a medium or material free of all forms of life
THREE BASIC WAYS OF STERILIZATION OF MEDIA?
STERILIZATION
- autoclaving
- ultraviolet radiation
- ethylene oxide
Exposure to steam at 121°C and 15 lbs of pressure of 15 minutes or longer, depending on the nature of the tem
will not survive longer than about 12 to 13 minutes
AUTOCLAVING
microorganisms & endospores
Around 260nm is quite lethal to many organisms but does not penetrate glass, dirt films, water, and other substances very effectively
@ biosafety cabinet
ULTRAVIOLET (UV) RADIATION
- Both microbicidal and sporicidal
- kills by covalently attaching to cell proteins
- particularly effective sterilizing agent because it rapidly penetrates packing materials, even plastic wraps
ETHYLENE OXIDE
