The EMB (Eosin Methylene Blue) agar is a selective and differential agar medium. It contains sucrose and lactose as fermentable substrates together with Eosin Y and methylene blue dyes which in combination gives the agar its characteristic color when prepared and serves as a pH indicator as well as an inhibitor of growth of Gram-positive bacteria. Hence, it is primarily used to isolate Gram-negative fecal coliforms while some positive fecal coliforms such as Staphylococci are also able to grow.
These coliforms are of two types:
- Lactose or sucrose fermenting coliforms form metallic sheens on the agar as a result of acid production and the response of the indicator to the increased acidity.
- Non-lactose/sucrose fermenters are only able to produce acid by protein deamination. Hence they either form colorless or pinkish colonies on the agar
On the other hand, Mannitol salt agar is a selective and differential agar medium that is primarily used to isolate Staphylococcal bacteria. The presence of sodium chloride in the medium makes it a partial or complete inhibitor of other bacteria.
Hence, an unknown bacterium that forms colorless colonies on EMB will either be a non-lactose fermenting, Gram-negative coliform that will hardly grow on Mannitol salt agar, or a Gram-positive fecal Staphylococcus.
Staphylococci bacteria are of two types:
- Coagulase-positive will form yellow colonies on the Mannitol salt agar.
- Coagulase-negative will form red colonies on the Mannitol salt agar.
More about isolating media can be found here: https://brainly.in/question/7238948
Answer:
<em>The definition of an organism is a creature such as a plant, animal or a single-celled life form, or something that has interdependent parts and that is being compared to a living creature. An example of an organism is a dog, person or bacteria. An example of an organism is one party in the political organism.</em>
Answer: Commonly known as deadly nightshade, belladonna, devil's cherry, and dwale. One of the most toxic plants found in the Western Hemisphere, all parts of the plant contain tropane alkaloids – as do those of its equally deadly sister species A.
Explanation: It contains several toxic alkaloids including coniine and is poisonous to humans and livestock. Consumption of just a small amount of any part of the plant can cause respiratory paralysis and death. Poison hemlock, with its purple-blotched stems, can cause paralysis if ingested.
