Genomic and Phenotypic Diversity among Ten Laboratory Isolates of Pseudomonas aeruginosa PAO1

Laboratory-adapted strains of bacteria are used throughout the world for microbiology research. These prototype strains help keep research data consistent and comparable between laboratories. However, we have observed phenotypic variability when using different strains ofPseudomonas aeruginosa PAO1, one of the major laboratory-adopted research strains. Here, we describe the genomic and phenotypic differences among 10 PAO1 strains acquired from independent sources over 15 years to understand how individual maintenance affects strain characteristics. We observed limited genomic changes but variable phenotypic changes, which may have consequences for cross-comparison of data generated using different PAO1 strains. Our research highlights the importance of limiting practices that may promote the microevolution of model strains and calls for researchers to specify the strain origin to ensure reproducibility.