Culture Media Preperation Flashcards
medium with the exact composition and amounts of the individual amino acids, vitamins, growth factors, and other components that make it up
are not exactly known
complex medium
- Specific nutritional requirements for growth are known
- specific chemical composition is known and individual components weighed out exactly to make up the medium
Defined Medium
Nutritional Requirements of Bacteria
- Carbon Source
- Energy Source
- Nitrogen
- Minerals
- Vitamins and Growth Factors
- Water
two groups based on their carbon requirements
- obtain their carbon from organic compounds
such as polysaccharides, carbohydrates, amino acids,
peptides, and protein
Heterotrophs
two groups based on their carbon requirements
- derive their carbon requirements from fixing carbon dioxide
autotrophs
Energy Source: Bacterial cells
- derive their energy needs from the breakdown
of organic molecules by fermentation or respiration
Chemoorganotrophs
Energy Source: Bacterial cells
- oxidize inorganic ions such as nitrate or iron to obtain energy to fix carbon dioxide
Chemolithotrophs
Energy Source: Bacterial cells
- contain photosynthetic
pigments such as chlorophyll or bacteriochlorophyll
that convert solar energy into chemical energy by
the process of photosynthesis
Photoautotrophs
Energy Source: Bacterial cells
- derive their energy requirements from photosynthesis, but their
carbon needs come from growth on organic molecules such as succinate or glutamate
photoheterotrophs
essential element in biolog-
ical molecules such as amino acids, nucleotide bases, and vitamins
Nitrogen
Example of nitrogen fixing bacteria
Rhizobium and Azotobacter
- essential in bacterial metabo-lism because they are cofactors in enzymatic reactions and are integral parts of molecules such as cyto-chromes, bacteriochlorophyll, and vitamins
Minerals
serve as coenzymes in metabolism
Vitamins and Growth Factors
medium that allows
certain bacteria to grow but will inhibit others from
growing
selective medium
contains substances that
cause some bacteria to take on an appearance that
distinguishes them from other bacteria.
differential medium
original media used by Louis Pasteur
urine or meat broth
Liquid medium is used for what?
diffuse growth
Solid medium is used for what?
discrete colonies
he cooked cut potato as early solid medium
Robert Koch
he discovered agar from seaweeds and algae
Walther Hesse
Classification of media based on consistency
Solid media
Semisolid media
Liquid media
Classification of media based on consistency
- contains 2% agar
- Colony morphology, pigmentation, hemolysis can be appreciated
Solid media
Classification of media based on consistency
- no agar
- For inoculum preparation, Blood culture, for the isolation of pathogens from a mixture.
Liquid media
Classification of media based on consistency
- 0.5% agar
Semi solid medium
Constituents Of Media
- Agar or agar- agar
- Peptone - mixture of partially digested proteins
- Yeast or meat extract
- NaCl
- Melting point : 98°C
- Solidifying point : 42°C
- % of agar : Solid media (2%)
Classification of media based on function or property
S.E.E.D. T.I.C.S
- Simple media
- Enriched media
- Enrichment broth
- Selective media
- Indicator media
- Differential media
- Composite media
- Transport media
Classification of media based on function or property
- Also called Basal medium
- Most commonly used in routine labs
Simple Media
Classification of media based on function or property
- Blood, serum or egg added to the basal medium.
- To grow bacteria which are more exacting in nutritional requirements
Enriched Media
- enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties
Blood Agar Media
Classification of media based on function or property
- For mixed cultures or materials containing more than one bacterium
- Contains substances which stimulates wanted bacteria & inhibits unwanted
bacteria
Enrichment Broth (media)
Classification of media based on function or property
- Substances added to a solid media to favour the growth of wanted bacteria
Selective Media
Classification of media based on function or property
- used to culture non-fastidious microorganisms that do not need extra growth nutrients
composite media
Classification of media based on function or property
– potato dextrose agar (PDA)
- Sabouraud Dextrose Agar (SDA)
– Fungi and yeast and also filamentous bacteria
Fungal Media
Classification of media based on function or property
- Change in the colour of indicator with the growth of bacteria
Indicator Media
Classification of media based on function or property
- To bring out differing characteristics of bacteria
Differential Media
Classification of media based on function or property
- have buffer solutions containing carbohydrates, peptones and other nutrients (excluding growth factors) designed to preserve the viability of bacteria during transport without allowing them to multiply.
Transport Media
MEDIA PREPARATION
CALCULATION
Using the formula: M1/V1 = M2/V2
– ratio and proportion
