What ingredients make media selective?
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 are selective media?
Selective media are used to select for the growth of a particular “selected” microorganism. For example, if a certain microbe is resistant to aparticular antibiotic (e.g., novobiocin), then that antibiotic can be added to the medium in order to. S. aureus is seen producing yellow colonies on mannitol salt agar.
What are the five main ingredients of culture media?
Some of the ingredients of culture media include water, agar, peptone, casein hydrolysate, meat extract, yeast extract and malt extract. Classification: Bacterial culture media can be classified in at least three ways; Based on consistency, based on nutritional component and based on its functional use.
What are the ingredients in culture media?
Components of culture media:
- Water– Source of hydrogen and oxygen.
- Electrolytes– NaCl & other electrolytes.
- Peptone– Mixture of partially digested proteins (animal or vegetable).
- Meat extract, yeast extract – Protein degradation products/carbohydrates/Inorganic salts/Growth factors.
- Blood– It enriches media.
Is nutrient agar a selective media?
Nutrient agar is a general-purpose media that is mostly used for routine culture or to ensure prolonged survival of microorganisms. It is one of the most important and commonly used non-selective media for the routine cultivation of microorganisms.
What are examples of selective media?
Examples of selective media:
- Eosin methylene blue contains dyes that are toxic for Gram-positive bacteria.
- YM (yeast extract, malt extract agar) has a low pH, deterring bacterial growth.
- MacConkey agar is for Gram-negative bacteria.
- Hektoen enteric agar is selective for Gram-negative bacteria.
Does MacConkey Agar contain lactose?
[2] MacConkey agar contains the essential nutrients required for microorganism growth. Additional key components include crystal violet dye, bile salts, lactose, and neutral red (a pH indicator). The lactose in the agar is a source of fermentation.
What is preparation of culture media?
Culture media preparation is one of the routine tasks common to many microbiology laboratories. This is true in the food industry, where producers regularly monitor food and environmental samples for spoilage and pathogenic microbes as an early indication of breakdown in processing hygiene.
What chemical ingredient makes MSA selective?
Mannitol Salt Agar
Mannitol Salt Agar (MSA) This is a medium that is both selective and differential. The high salt concentration (7.5%) is the selective ingredient. Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below).