Effects of ozone on the cytomembrane and ultrastructure of Pseudomonas aeruginosa

The ozone impact on Pseudomonas aeruginosa ATCC27853 cells was studied. Ozone-induced loss of K+, Mg2+, and ATP was measured using inductively coupled plasma/mass spectrometry and a bioluminescence assay. Maximum releases of K+ and Mg2+ were achieved at 0.37 mg/L of ozone after 2 min with a killing rate of culturable bacteria greater than 93%. Maximum release of ATP was attained at 0.42 mg/L of ozone after 3 min. Transmission electron microscopy showed that shapes of treated cells were integrated, but cytoplasmic agglutinations and vacuoles appeared. Ozone treatment caused lysis of P. aeruginosa cells to be sensitive to sodium dodecyl sulfate, insensitive to NaOH, and subject to inactivation by proteinase K. A combined action of cytoplasm agglutination, protein denaturation, and membrane permeabilization, rather than cell lysis, leads to non-culturability of P. aeruginosa cells.