The anti-sigma factor MucA of Pseudomonas aeruginosa: dramatic differences of mucA22 vs. DmucA mutants in anaerobic acidified nitrite sensitivity of planktonic and biofilm bacteria in vitro and during chronic murine lung infection

In this study, the A-NO2- sensitivity of mucA22 mutant bacteria vs. a genome sequence-confirmed mucA deletion (∆mucA) mutant was determined. The ∆mucA is surprisingly more resistant to A-NO2- than mucA22 bacteria. The genes responsible for the disposal of nitric oxide (NO), a by-product of A-NO2-, were found to be near wild-type levels in the ∆mucA mutant yet were dramatically reduced in the mucA22 mutant. Pseudomonas aeruginosa wild-type (PAO1), mucA22 and ∆mucA bacteria were grown for 24 hr under anaerobic conditions in LBN (10g/l Tryptone, 5 g/l yeast extract, 5g/l NaCl, 100 mM KNO3), pH 6.5, followed by treatment of each organism with 15 mM A-NO2- for 20 min.