The effectiveness of UV-C towards the toxin and odor of M. aeruginosa at population and single cell levels were investigated in three ways. In the absence of UV-C, MC-LR and beta-cyclocitral production show similar pattern of incremental rate with growth rate on population level shown as intracellular concentrations of MC-LR (C-MC) and beta-cyclocitral (C-BCC), but the cellular quota of MC-LR (Q(MC)) and beta-eyclocitral (Q(BCC)) at single-cell level reached the maximum values, 37.5 +/- 1.2 fg cell(-1) and 4.3 +/- 0.1 fg cell(-1), just after the early exponential phase. Second, upon UV-C irradiation, the C-MC consistently decreased by 10-41% with increase of UV-C dosage (50-200 mJ cm(-2)) while C-BCC increased by 2-14%. Third, during the 14 days' post-UV incubation, UV-C at 75-200 mJ cm(-2) induced remarkable suppressing effects on both C-MC and C-BCC for 3-14 days. The suppressing effects on Q(MC) and Q(BCC) were induced by UV-C at 100 mJ cm(-2) and above, with shorter suppressing periods by 1-4 days and lower decremental rates by 21%-30% than that of C-MC and C-BCC, indicating interruptions on biosynthesis processes partially contribute to suppression effects of C-MC and C-BCC. The suppression effect on either C-BCC or Q(BCC), with higher decrement rates while lower recovery rates, was more severe than C-MC and Q(MC).