Anaerobic physiology of Pseudomonas aeruginosa in the cystic fibrosis lung.

During chronic infection of the cystic fibrosis (CF) lung, Pseudomonas aeruginosa grows and persists in a microaerobic to anaerobic environment. P. aeruginosa is well adapted to thrive under such conditions and contains multiple enzyme systems for energy generation under oxygen-restricted or even anaerobic conditions. Recent data confirm a heterogeneous environment in the CF lung and indicate that P. aeruginosa induces enzyme systems for microaerobic growth but also denitrification and fermentative pathways. Moreover, stress response systems as universal stress proteins enhance survival under anaerobic energy starvation conditions. Growth in these oxygen-limited environments induces a drastic physiological change in P. aeruginosa, like increased alginate production and alterations in the outer membrane, which contribute to an increased antibiotic tolerance.