Phenylethyl Alcohol Agar PEA Recipe: Pancreatic digest of casein, papaic digest

Question

Phenylethyl Alcohol Agar

PEA Recipe: Pancreatic digest of casein, papaic digest of soybean meal, sodium chloride, b-Phenylethyl alcohol, agar, distilled or deionized water.

1. Is PEA a defined or an undefined medium? Provide the reasoniing behind your choice and explain why this formulation is desirable.

2.Growth on the PEA and NA plates was recorded as ''good growth,'' ''poor growth,'' or ''no growth.'' These are qualitative and, at least for the first two, subjective terms. What did you use to establish what constituted ''good growth?''

3. Would removing B-phenylethyl alcohol from PEA alter the medium's sensitivity or specificity?

4.If you observed growth on Gram-negativeorganisms on the PEA plate you inoculated, does this negate the usefulness of PEA as a selective medium? Why or why not?

I WOULD REALLY APPRECIATE SOME HELP WITH THESE QUESTIONS. I WILL RATE CORRECT ANSWERS. THANK YOUR VERY MUCH. MICROBIOLOGY LAB.

Explanation / Answer

1.PEA or phenyl ethylene alcohol agar is a defined media.because this media contain components permit the growth of only gram positive bacteria. and all the component of the media are known and specific as they prevent any gram negetive bacteria growth.

2. a good growth mean optimum growth of the selected type of bacteria that bringout special characters. in good growth in plate each organism forms a separate colony and growth is visualised in plate. NA media permits rapid growth for most microbe but PEA IS SELECTED FOR GRAM POSITIVE ONES.

3.B-PHENYLETHYL ALCOHOL removing will alter the specificity of this media as it is the main component that inhibit the growth of gram negetive bacteria. it disrupt the lipid structure in the membrane of gram negetive bacteria and also interfere with protein and DNA synthesis of gram negetive.

4. yes PEA media is a selective media used to grow gram positive bacteria. so any gram negetive bacteria growing will negate the usefulness of PEA medium.

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