Pseudomonas aeruginosa displays a dormancy phenotype during long-term survival in water

Abstract

Pseudomonas aeruginosa is capable of long-term survival in water, which may serve as a reservoir for infection. Although viable cell counts of PAO1 incubated in water remain stable throughout 8 weeks, LIVE/DEAD staining indicated a high proportion of cells stained with propidium iodide (PI). The proportion of PI-stained cells increased by 4 weeks, then decreased again by 8 weeks, suggesting an adaptive response. This was also evident in an observed shift in cell morphology from a rod to a coccoid shape after 8 weeks. Fluorescence-activated cell sorting (FACS) was used to recover PI-stained cells, which were plated and shown to be viable, indicating that PI-stained cells were membrane-compromised but still cultivable. PAO1 mid-log cells in water were labeled with the dsDNA-binding dye PicoGreen to monitor viability as well as DNA integrity, which demonstrated that the population remains viable and transitions towards increased dsDNA staining. Metabolic activity was found to decrease significantly in water by 4 weeks. The PAO1 outer membrane became less permeable and more resistant to polymyxin B damage in water, and the profile of total membrane lipids changed over time. Among the ~1400 transcriptional lux fusions, gene expression in water revealed that the majority of genes were repressed, but subsets of genes were induced at particular time points. In summary, these results indicate that P. aeruginosa is dormant in water and this adaptation involves a complex pattern of gene regulation and changes to the cell to promote long-term survival and antibiotic tolerance. The approach of P. aeruginosa incubated in water may be useful to study antibiotic tolerance and the mechanisms of dormancy and survival in nutrient limiting conditions.

Antimicrobial activity of enterocin obtained from Enterococcus durans on Shiga-like toxin-producing Escherichia coli

“…Propidium iodide is a membrane impermeant intercalator DNA that only stains cells with compromised membrane integrity, presenting with the reddish coloration (LEWENZA et al, 2018;ROCHA et al, 2019). Our data shows the intensity of the reddish color in the first 6 h of STEC in contact with the enterocins (Figure 2); therefore, indicating the penetration of PI.…”

From genotype to phenotype: adaptations of Pseudomonas aeruginosa to the cystic fibrosis environment

“…In fact, the high plasticity of the P. aeruginosa core and accessory genome allows the bacterium to colonize a wide variety of environments, such as soils, water or abiotic surfaces [1–4]. However, P.…”

“…The ability of Pseudomonas aeruginosa to establish a chronic infection in cystic fibrosis (CF) lungs despite a wide range of stress sources highlights its high adaptability. In fact, the high plasticity of the P. aeruginosa core and accessory genome allows the bacterium to colonize a wide variety of environments, such as soils, water or abiotic surfaces [1][2][3][4]. However, P. aeruginosa adaptive processes have been especially described in the context of pulmonary infections.…”

Triclosan depletes the membrane potential in Pseudomonas aeruginosa biofilms inhibiting aminoglycoside induced adaptive resistance

“…A similar experiment incubating P . aeruginosa biofilm in nutrient poor conditions demonstrated a decrease in ATP levels without a loss of viable bacteria [ 68 ]. Consistent with this previous study, we observed that the levels of ATP in the untreated biofilm were lower in the five day DPBS incubated biofilms compared with 24 hour biofilms as determined by BacTiterGlo analysis while the colony forming units (CFUs) were not significantly different ( S8 Fig ).…”