Mechanisms of inactivation of bacteriophage φX174 and its DNA in aerosols by ozone and ozonized cyclohexene

Abstract

The mechanisms of inactivation of aerosolized bacteriophage øX174 in atmospheres containing ozone, cyclohexene, or ozonized cyclohexene were studied by using 32P-labelled phage. The inactivation of the aerosolized phage in clean air or in air containing cyclohexene is due to damage of the protein coat since the deoxyribonucleic acid (DNA) extracted from the inactivated phage retains its biological activity. Inactivation of the phage in air containing ozone is mainly due to protein damage whereas inactivation in air containing ozonized cyclohexene is due both to protein and DNA damage. Sucrose gradient analysis shows that aerosolized inactivated øX174 releases unbroken DNA. In contrast, the DNA from phage øX174 inactivated by ozonized cyclohexene is broken.The inactivation of aerosolized phage øX174-DNA was studied in the same atmospheres using 32P-labelled DNA. øX174-DNA aerosolized in clean air or air containing cyclohexene at 75% r.h. is inactivated by a factor of 2 in 30 min. The inactivated DNA is broken. Ozone as well as ozonized cyclohexene inactivates DNA very fast causing breaks in the molecule. This is in contrast with the intact bacteriophage in which ozone does not produce breaks in the DNA.