Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2001 Sep;67(9):4225-32.
doi: 10.1128/aem.67.9.4225-4232.2001.

Photoreactivation in Airborne Mycobacterium Parafortuitum

Affiliations
Free PMC article

Photoreactivation in Airborne Mycobacterium Parafortuitum

J Peccia et al. Appl Environ Microbiol. .
Free PMC article

Abstract

Photoreactivation was observed in airborne Mycobacterium parafortuitum exposed concurrently to UV radiation (254 nm) and visible light. Photoreactivation rates of airborne cells increased with increasing relative humidity (RH) and decreased with increasing UV dose. Under a constant UV dose with visible light absent, the UV inactivation rate of airborne M. parafortuitum cells decreased by a factor of 4 as RH increased from 40 to 95%; however, under identical conditions with visible light present, the UV inactivation rate of airborne cells decreased only by a factor of 2. When irradiated in the absence of visible light, cellular cyclobutane thymine dimer content of UV-irradiated airborne M. parafortuitum and Serratia marcescens increased in response to RH increases. Results suggest that, unlike in waterborne bacteria, cyclobutane thymine dimers are not the most significant form of UV-induced DNA damage incurred by airborne bacteria and that the distribution of DNA photoproducts incorporated into UV-irradiated airborne cells is a function of RH.

Figures

FIG. 1
FIG. 1
UV-induced inactivation and PR of M. parafortuitum in liquid suspension. Results from three independent trials are presented. Symbols represent UV-irradiated total bacteria with visible light (□) and without visible light (▵), culturable bacteria with visible light (○) and without visible light (■), and culturable bacteria irradiated by UV (●). Average UV spherical irradiance was 7.5 ± 0.3 (SE) μW/cm2.
FIG. 2
FIG. 2
Z value response for airborne M. parafortuitum in the presence (○) and absence (●) of visible light. UV spherical irradiance was 3.7 μW/cm2. All error bars represent 1 SE.
FIG. 3
FIG. 3
UV inactivation rate for M. parafortuitum at different UV spherical irradiance levels in the absence (●) and presence (○) of visible light. Error bars represent 1 SE. All results were based on a UV exposure of 9 min at each spherical irradiance. Average normalized UV inactivation rate (Z value response in the absence of PR light) was 8.5 × 10−4 cm2/μW · s.
FIG. 4
FIG. 4
Z value response determined for airborne B. subtilis spores at 50 and 95% RH. Average UV spherical irradiance was 7.5 ± 0.13 (SE) μW/cm2. Error bars represent 1 SE.
FIG. 5
FIG. 5
Z value response and amounts of CTDs incorporated into DNA for UV-irradiated airborne S. marcescens (A) and M. parafortuitum (B). Average UV spherical irradiance was 7.5 μW/cm2 ± 0.13 μW/cm2. Error bars represent 1 SE. Volume represents the integrated intensity of all pixels in a defined area by immunofluorescence.

Similar articles

See all similar articles

Cited by 10 articles

See all "Cited by" articles

Publication types

LinkOut - more resources

Feedback