Lecture 4A: Culture Media, Biosafety and Aseptic Technique Flashcards
Culture _____ (sing.)
medium
Culture ____ (plu.)
media
_____ - is a nurtient-rich liquid or gel designed to support the growth of a target species or group of species.
Culture medium
is a ______________________ designed to support the growth of a target species or group of species.
nutrient-rich liquid or gel
What does culture medium/media typically contain?
- water
- energy source, usually a carbohydrate
- nitrogen source (eg. amino acids, protein sequences such as pepton)
- mineral salts (MgSO4, NaCl, KH2PO4)
- special growth factors (if needed)
General composition of medium;
- H-donors and acceptors
- C-source
- N-source
- Inorganic nutrients
- Trace elements
- Growth factors
- Solidifying agent
- Solvent (usually distilled water)
- Buffers
General composition of medium;
H-donors and acceptors
~1-15 g/L
General composition of medium;
C-source
~1-20 g/L
General composition of medium;
N-source
~0.2-2 g/L
General composition of medium;
Inorganic nutrients
e.g. S, P, (~50mg/L)
General composition of medium;
Trace elements
(0.1-1 μg/L
General composition of medium;
Growth factors
- aminoacids, purines, pyrimidines, occasionally 50 mg/L,
- vitamins occasionally 0.1-1 mg/L
General composition of medium;
Solidifying agent
- eg. Agar (8-20 g/L) (if semi-solid or solid medium)
(3)Types of culture media based on physical state
- Solid medium
- semisolid medium
- liquid (broth) medium
- for isolation of colonies , which give distinct morphology on the surface of the medium
- commonly employs agar as the solidifying agent, added at 1.5-2% (or 1.5-2.0 g/100ml of medium)
- agar is a golden-yellow granular powder prepared from seaweeds
Solid medium
Solid medium melts at ___ and gels at ____
melts at 80°C and gels at <40°C
- prepared with agar at concentrations of
0.8% or less. - has a soft custard-like consistency and is useful for the cultivation of microaerophilic bacteria or for the determination of bacterial motility.
Semisolid medium
Semisolid medium has a soft custard-like consistency and is useful for the cultivation of _______ _______ or for the ____ _ ____ ____.
-microaerophilic bacteria
- determination of bacterial motility
- contain specific amounts of nutrients but do not contain solidifying agent.
- serves various purposes such as propagation of a large number of organisms, fermentation studies, and various other tests. e.g. sugar fermentation tests, MR-VR broth
liquid (broth) medium
- serves various purposes such as propagation of a large number of organisms, fermentation studies, and various other tests. e.g. __ ____ __, __ __
- sugar fermentation tests, MR-VR broth
Microoganism can be classified depending on ____
oxygen requirements
Classifications of microorganisms
- Aerobic
- Facultative
- Anaerobic
- Capnophilic
- Microaerophilic
requires O2
- aerobic
can grow in the presence or absence of O2
- facultative
growth in the absence of O2
- anaerobic
CO2 stimulates growth
capnophilic
require slightly decreased O2 tenstion
microaerophilic
(2) Types of culture media based on composition / ingredients
- Complex
- Defined /synthetic
with 1 or more unknown components, with complex ingredients
- eg. peptone, extracts, hydrolysates; rich medium
Complex
examples of complex media
- potato dextrose agar/broth
- nutrient agar/broth
proportion and identity of all components are known; pure chemical substances; may not be as rich as CM
Defined / Synthetic
Types of culture media based on purpose
- General Purpose media
- Enrichment media
- Selective media
- Differential Media
- Transport media
- Anaerobic media