N-Alkane Assimilation by Pseudomonas aeruginosa and Its Interactions with Virulence and Antibiotic Resistance

Pseudomonas aeruginosa strains with potential for degrading n-alkanes are frequently cultured from hydrocarbon-contaminated sites. The initial hydroxylation step of long-chain n-alkanes is mediated by the chromosomally encoded AlkB1 and AlkB2 alkane hydroxylases. The acquisition of an additional P. putida GPo1-like alkane hydroxylase gene cluster can extend the substrate range assimilated by P. aeruginosa to n-alkanes. Efficient niche colonization of hydrocarbon-contaminated sites is facilitated by avid iron-uptake systems, such as pyoverdine, and the production of several compounds with antimicrobial activities. A GPo1-like gene cluster can facilitate detoxification and solvent tolerance in P. aeruginosa. The overproduction of various multidrug efflux pumps, in particular, the MexAB-OprM system, can also contribute to solvent tolerance, which is often associated with reduced susceptibility or full resistance to certain clinically relevant antibiotics. These characteristics, together with the remarkable conservation of P. aeruginosa virulence determinants among human, animal, and environmental isolates, necessitate further studies from a One Health perspective into the acquired antibiotic resistance mechanisms of environmental P. aeruginosa strains and possible ways for their dissemination into the human population.