Sequence diversity of the mucABD locus in Pseudomonas aeruginosa isolates from patients with cystic fibrosis

Abstract

ThemucAgene of themucoperon, which is instrumental in the control of the biosynthesis of the exopolysaccharide alginate, is a hotspot of mutation inPseudomonas aeruginosa, a micro-organism that chronically colonizes the airways of individuals with cystic fibrosis (CF). ThemucA,mucBandmucDgenes were sequenced in nine environmental isolates from aquatic habitats, and in 37P. aeruginosastrains isolated from 10 patients with CF, at onset or at a late stage of chronic airway colonization, in order to elucidate whether there was any association between mutation and background genotype. The 61 identified single nucleotide polymorphisms (SNPs) segregated into 18mucABDgenotypes. Acquired andde novostopmucAmutations were present in 14 isolates (38 %) of fivemucABDgenotypes. ΔG430 was the most frequent and recurrentmucAmutation detected in four genotypes. The classification of strains bymucABDgenotype was generally concordant with that by genome-wide SpeI fragment pattern or multilocus SNP genotypes. The exceptions point to intragenic mosaicism and interclonal recombination as major forces for intraclonal evolution at themucABDlocus.