Question

7. Look up and define the following media. Indicate the type of bacteria that can grow on each media

a. Nutrient agar

b. Trypticase Soy agar

c. Blood agar

Answer 1

Nutrient agar media

1. Nutrient agar is a common purpose medium which supporting growth of a huge range of non-fastidious organisms. It typically contains (mass/volume): 0.5% Peptone - this provides organic nitrogen. 0.3% beef extract/yeast extract - the water-soluble content of these contribute vitamins, carbohydrates, nitrogen, and salts.
2. Where as these ingredients are combined and boiled for approximately one minute to ensure they are mixed and to sterilize them.
3. Then they are cooled to around 50 °C (122 °F) and poured into Petri dishes which are covered immediately. Once the dishes hold solidified agar, they are stored upside down and are often refrigerated until used.
4. Inoculation takes place on warm dishes rather than cool ones: if refrigerated for storage, the dishes must be rewarmed to room temperature prior to inoculation.

Example Non-fastidious organisms Streptococcus

Agar media

1. These type of media where Agar are growth media for the culturing of bacteria. They are common-purpose, nonselective media providing enough nutrients to allow for a wide variety of microorganisms to grow.
2. This is an agar plate is a Petri dish that contains a solid growth medium, typically agar plus nutrients, used to culture small organisms such as microorganisms.
3. They are used for a wide range of applications, including culture storage, enumeration (counting), isolation of pure cultures, or simply general culture.

Example Fastidious bacteria or antimicrobial agents to permit the selection of various microbial groups from pure microbiota. non-fastidious organisms Neisseria gonorrhoeae Campylobacter spp Helicobacter spp

Blood Agar (BA)

1. These type of media are enriched medium used to culture those bacteria or microbes that do not grow easily. Such bacteria are called fastidious as they demand a special, enriched nutritional environment as compared to the routine bacteria.
2. It contains general nutrients and 5% sheep blood. It is useful for cultivating fastidious organisms and for determining the hemolytic capabilities of an organism. Some bacteria produce exoenzymes that lyse red blood cells and degrade hemoglobin; these are called hemolysin
3. Blood Agar is used to grow a wide range of pathogens particularly those that are more difficult to grow.

Example such as Haemophilus influenzae, Streptococcus ,pneumoniae and Neisseria species.