When would chemically defined media be used?
When would chemically defined media be used?
A chemically defined medium is a growth medium suitable for the culture of microbes or animal cells (including human) of which all of the chemical components are known.
Why different media are used for the growth of different bacteria?
Chemically defined media contain only chemically known components. Selective media favor the growth of some microorganisms while inhibiting others. Differential media help distinguish bacteria by the color of the colonies or the change in the medium.
Why do media need pathogens to grow?
Transport media Maintain the viability of all organisms in the specimen without altering their concentration. Contain only buffers and salt. Lack of carbon, nitrogen, and organic growth factors so as to prevent microbial multiplication.
What is used to grow cultures of microorganisms?
The most common growth media for microorganisms are nutrient broths and agar plates. Open cultures allow for a replenishment of nutrients and a reduction of waste buildup in the media. Selective media are used for the growth of only selected microorganisms.
What is an example of selective media?
Selective medium contain particular ingredients that inhibit the growth of certain microbes. An example of a selective medium is MacConkey agar. It contains bile salts and crystal violet, which interfere with the growth of many gram-positive bacteria and favor the growth of gram-negative bacteria.
What is meant by differential media?
Differential media contain compounds that allow groups of microorganisms to be visually distinguished by the appearance of the colony or the surrounding media, usually on the basis of some biochemical difference between the two groups.
What does blood agar differentiate between?
Blood agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.
Does pH affect Agar?
The pH noticeably affects the strength of the agar gel; as the pH decreases, the gel strength weakens. Sugar content has also a considerable effect over agar gel.
Why Agar is called agar-agar?
The word ‘agar’, or ‘agar-agar’, currently used, comes from Malay. In the 19th century, Chinese migrants brought the Japanese product to Malaysia, and adopted the local name of ‘agar’, which means ‘jelly’ or ‘gelatin’. When the Japanese ‘kanten’ entered Europe, it did so with the Malay name of ‘agar’.