[Effects of different phosphorus sources on the growth and toxin production of Prorocentrum lima]

To explore the nutrient properties of Prorocentrum lima and biosynthesis mechanism of diarrhetic shellfish poison (DSP), the growth and activities of alkaline phosphatase of Prorocentrum lima were observed under different phosphorus sources. DSP productions were also analyzed. The maximum growth rate (micro(max)) was slightly lower under beta-sodium glycerophosphate than those under NaH2PO4 and ATP as phosphorus sources, respectively. The maximum biomass (X) under ATP was higher than those under NaH2PO4 and beta-sodium glycerophosphate as the phosphorus sources, respectively. When the concentration of NaH2PO4 was below 2 micromol/L, the activity of alkaline phosphatase increased significantly. However, the activities were much low in the all treatments when beta-sodium glycerophosphate used as phosphorus source, whereas the activities increased with the concentration of ATP when ATP used as phosphorus source. The level of okadaic acid (OA) in Prorocentrum lima at the stationary phase under beta-sodium glycerophosphate was higher than those under NaH2PO4 and ATP. These suggested that beta-sodium glycerophosphate could be utilized directly by Prorocentrum lima with lower efficiency; ATP could induce alkaline phosphatase to produce inorganic phosphate for algae. DSP production in Prorocentrum lima were different under various phosphate sources, beta-sodium glycerophosphate enhanced production of DSP. The difference in DSP production might be related with the physiological state of Prorocentrum lima.