[Overcompensation effect of Pavlova viridis under ultraviolet (UV-B) stress]

To examine the existence of overcompensation growth of microalgae, this paper studied the effects of UV-B stress on the production of bioactive substances during the overcompensation of Pavlova viridis. Six groups of UV-B treatments 18, 36, 54, 65, 86 and 108 J x m(-2) as well as the control were set up for this study. After the UV-B stress relieved, the treated groups and the control were simultaneously cultured for 12 days under the same inoculation density and normal culture conditions, and the parameters OD, biomass, chlorophyll a, carotenoid, cellular protein and carbohydrate were measured. The results showed that under UV-B stress, the growth of P. viridis was inhibited significantly (P < 0.05), with a decrease of relative growth rate being 16.15% - 60.00%, compared with the control. But, after the relief of UV-B stress, the growth rate during anaphase was significantly higher (P < 0.05) in UV-B treatments than in the control, indicating the occurrence of overcompensation growth. On the 12th day of culture, the OD, biomass, chlorophyll a, carotenoid, cellular protein and carbohydrate in treated groups were 22.38%, 15.00%, 26.15%, 23.81%, 11.63% and 27.58% higher than those in the control, respectively. The overcompensation growth of P. viridis provided an effective way to exploit the bioactive substances of microalgae.