[Induction of biochemical composition in Heterosigma akashiwo under Fe stress]

The iron-stress mediated effects on biochemical constituents of red tide alga H. akashiwo were examined in Fe-replete and iron deficiency, and low iron batch cultures. The content of all pigments decreased under iron limitation, and the cellular chlorophyll a concentration decreased by more than 2-fold compared to that under iron replete condition. This change in Chl a was accompanied by a corresponding decrease in Chl c per cell, resulting in no trend in the ratio of Chl c to Chl a. The cellular carotenoids content decreased by more than 1.5-fold compared to that under iron replete condition. As a consequence, carotenoids/chlorophyll a ratio increased in Fe-deficient cells. Carbohydrate content was reduced under iron stress, and total proteins decreased with the decrease of iron concentration. A crude fractionation of the soluble proteins demonstrated that 17 kD and 55 kDa proteins in soluble fraction were induced.