UV-B AND UV-A RADIATION EFFECTS ON PHOTOSYNTHESIS AT THE MOLECULAR LEVEL - Environmental UV Radiation: Impact on Ecosystems and Human Health and Predictive Models - page 127

grow as the wild-type under visible light, in the absence of UV-B radiation. This result
shows that the photolyase encoded by the slr0854 gene is indispensable for growth in the
presence of UV-B radiation, but DNA damage which could occur under normal growth
conditions is either not significant or can be repaired by systems other than photolyase.

'slr0854 WT

Figure 9. The effect of photolyase (slr0854) inactivation on the growth of Synechocystis 6803 under
UV-B. Wild-type and 'slr0854 cells were inoculated on agar plate and grown under visible light for 2
days. The visible light was then complemented with UV-B, and the cells were grown for another 3 days.

100

80

No addition

60

+ lincomycin

40

20

0

0 0 0 0 0 0 0

Time (min)

Figure 10. The effect of photolyase (slr0854) inactivation on the UV-B induced loss of PSII activity.
Wild-type (circles) and 'slr0854 cells (squares) were cultured under visible light. The cultures were
exposed to UV-B radiation complemented with visible light in the absence (open symbols) and presence
of lincomycin (closed symbols).