RECA-DEPENDENCE OF THE RESPONSE OF PSEUDOMONAS-AERUGINOSA TO UVA AND UVB IRRADIATION

The responses of the autochthonous soil and aquatic organism, Pseudomo nas aeruginosa to UV radiation wavelengths (UVA, 320-400 nm, and UVB, 280-320 nm) has been investigated in this study. P. aeruginosa recA mu tants were found to be more sensitive to both UVA and UVB radiation th an were their isogenic RecA(+) parents. Introduction of a low-copy-num ber plasmid containing the cloned wild-type P. aeruginosa recA gene re stored UVA and UVB resistance to recA mutants. The concentration of Re cA protein increased twofold 120 min after exposure to either UVA or U VB radiation, suggesting induction of expression of the recA gene by t hese wavelengths, In this study, we found that a functional RecA prote in is required for activation of D3 prophage in lysogenic cells follow ing exposure to UVB radiation. Prophage were not induced by exposure o f their hosts to UVA radiation. Induction of damage-inducible (din) ge nes in response to UVA or UVB irradiation was also shown to be RecA de pendent. These data indicate that the recA gene plays a role in the re sponse of P. aeruginosa to exposure to wavelengths of UV radiation fou nd in the solar spectrum.