Bacterial populations differentiate at the subspecies level into clonal complexes. Intraclonal genome diversity was studied in 100 isolates of the two dominant Pseudomonas aeruginosa clones C and PA14 collected from the inanimate environment, acute and chronic infections. The core genome was highly conserved among clone members with a median pairwise within-clone single nucleotide sequence diversity of 8 × 10(-6) for clone C and 2 × 10(-5) for clone PA14. The composition of the accessory genome was, on the other hand, as variable within the clone as between unrelated clones. Each strain carried a large cargo of unique genes. The two dominant worldwide distributed P. aeruginosa clones combine an almost invariant core with the flexible gain and loss of genetic elements that spread by horizontal transfer.
© 2015 The Authors. Environmental Microbiology Reports published by Society for Applied Microbiology and John Wiley & Sons Ltd.