SMOX and cystic fibrosis: We then compared the RhlR core regulon to the QS regulons reported by Chugani and colleagues for PAO1 and 4 environmental isolates (referred to as the Chugani environmental core; 5 strains, 42 genes) and a core QS regulon among 2 CF isolates (Chugani CF core; 2 strains, 25 genes) (40).