Figure 1. Schematic represents quorum sensing controlled expression of genes for phenazine production. P. aeruginosa synthesizes acylated homoserine lactones (AHLs) and Pseudomonas quinone signaling (PQS) as their primary and secondary quorum sensing signaling molecules. PQS regulates the synthesis of phenazine-1-carboxylic acid (PCA) through a set of primary phenazine producing genes phzA1-G1 and phzA2-G2. PCA then converts into various kinds of specific phenazine encoded by specific genes.