DATA Lab Section SHEET 4-7 (oontinued and performed this exercise (nitials 7 Thi

Question

DATA Lab Section SHEET 4-7 (oontinued and performed this exercise (nitials 7 Think about the results you recorded. These are q constituted "good grosetht on the HE agar and NA plates was recorded as "good growth," "poor growth," or "no grouth. ualitative and, at least for the first tvo, subjective terms. What did yow use to establish what b. Why wouldn't it be advisable to compare growth of the organisms on each plate to each othert There are at least two answers to this question! your answer. Would removing bile salts from HE agar alter the medium's sensitivity or specificity? Explain

Explanation / Answer

a) To maintain good growth following points can be considered

1.Proper enriched media

2. Good aeration

3. Proper incubation temperature

4. Proper streaking or plating with optimum quantity of culture

b) No it is not advisable to compare the growth of each plate with each because it might give inaccurate result. The inaccuracy may be due to different factor-

1. The growth media ,ight be different. Different media produces different colonies of bacteria.

2. The amount of culture plated could vary during streaking or plating.

3. Contamination might cause different number of colonies in different plates

c) Bile salts removal from HE agar will affect its specificity.

Bile slats in HE agar is used to inhibit the growth of Gram positive bacteria and allows the growth of gram negative bacterias such as Salmonella, Shigella etc. If we remove bile salts gram positive bacterias will also grow in the medium causing contamination of Salmonella, Shigella colonies.

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