The aim of this book is to further highlight the importance of media composition on gene expression. Under conditions of iron limitation, Pseudomonas aeruginosa secretes pyoverdine to help bind iron from the external environment. The ferripyoverdine receptor, fpvA , is the receptor P. aeruginosa uses to internalize iron bond to pyoverdine. FpvA was cloned and identified to have a molecular mass of 89,395 daltons (Meyer et al., 1990, Poole et al., 1993) . In addition to playing the role of a receptor to iron bound to pyoverdine, the fpvA gene has also been hypothesized to be targeted by antibiotics and bacteriophages and serve as entry points for them. The arylamidase enzyme (EC 3.4.11.2] is the enzyme that catalyzes the hydrolysis of an N-terminal amino acid from peptides, amides or arylamides. It was purified decades ago and was estimated to weigh about 71 kDa by Riley and Behal (1970). The fpVA and the arylamidase enzyme may possibly interact or may be similar in their manner of functioning based on scientific observations decades ago from the research work done by Riley and Behal (1970), and the recent observations by Osayande, JO (2013) and Bishop et al., 2017.