Physiological and biochemical responses of Phaeodactylum tricornutum and Chaetoceros minutissimus to enhanced UV-B irradiation

The effects of UV-B irradiation on the growth,physiological and biochemical characteristics including chlorophyll,Car,MDA,soluble protein contents and antioxidant enzyme activity of Phaeodactylum tricornutum and Chaetoceros minutissimus were studied by using experimental ecology and biochemical methods. The results are as follows.(1) UV-B irradiation could inhibit the growth of two marine microalgae species; however,low-dose of UV-B irradiation(0.75 J/m2) could stimulate the growth of P.tricornutum.(2) Two microalgal species exposed to UV-B radiation had lower content of chlorophyll than the control. The chlorophyll content of P. tricornutum increased first and then decreased; C. minutissimus showed a decreasing trend with increasing dose of UV-B radiation. The MDA contents of two microalgal species increased with increasing dose of UV-B radiation.(3) The soluble protein content of P. tricornutum under enhanced UV-B irradiation increased first and then decreased; C. minutissimus showed a decreasing trend from the beginning to the end.(4) The SOD,POD and CAT activities of two marine microalgae increased first and then decreased,whereas C. minutissimus showed a relatively stable change under UV-B irradiation.