Would removal of sodium chloride from MSA alter the mediums

Would removal of sodium chloride from MSA alter the medium\'s sensitivity or specificity? Explain your answer (See pages 8 and 9, \"A Word About Experimental Design, \" for assistance with these terms.) Suppose a mistake is made in preparing a batch of MSA and the starting pH is 7.4 of 7.0-7.2. Would that affect the medium\'s sensitivity of specificity? Explain your answer, (see pages 8 and 9, \"A world about experimental design, \"for assistance with these terms.)

Solution

7)Sodium chloride is an important component of Mannitol salt agar medium. It is about 10%. This much salt concentration makes this media selective for certain Gram positive bacteria that can tolerate this much salt concentration. Other bacteria fail to grow in such high salt concentration.

So if the sodium chloride is removed from medium certain unwanted bacteria will grow and the media will be no more selective for the Gram Positive bacteria.

8) Since this medium is differential and can act as pH indicator for in order to detect acid produced by mannitol-fermenting staphylococci. So it is important that pH is not disturbed.