Carboxyl groups have an electronegative oxygen atom double bonded to a carbon atom. This carbon-oxygen bond is very polar and the fact that its a double bond increases the polarity of the bond.
PEA agar, also referred to as Phenylethyl Alcohol Agar is a medium  used by microbiologists to grow microorganisms. The ingredient that  supplies nitrogen is casein. Making the world better, one answer at a time.
Phenylethyl Alcohol Agar. Phenylethyl alcohol agar (PEA) is a selective medium used to cultivate Gram positive organisms. The active ingredient, phenylethyl alcohol, inhibits or markedly reduces growth of Gram negative organisms by interfering with DNA synthesis.PEA also prevents Proteus species from swarming across the surface of the agar.Staphylococcus aureus, a Gram positive organism, grows on this PEA plate while Serratia marcescens, a Gram negative organism, does not.EA also prevents Proteus species from swarming across the surface of the agar. Staphylococcus aureus, a Gram positive organism, grows on this PEA plate while Serratia marcescens, a Gram negative organism, does not.