Effect of different concentration of soil extracts on the growth of Pyrodinium bahamense var. Compressum

Pyrodinium bahamense var. compressum (Pbc) the main species that caused Paralytic Shellfish Poisoning (PSP) in Sabah has been extensively studied for the toxin content. The difficulty of maintaining Pbc culture to reach the desired concentration is explained by its specific nutrition needs. The primary purpose of this research is to determine the effect of soil extracts in improving cell growth of Pbc in laboratory conditions. Pbc cells were grown for 22 days in F/2 media enriched with different concentrations of soil extracts (0%- 35%). The culture was maintained in a temperature-controlled room at 25±0.5 oC. The cells were illuminated at 100 μmol m-2s -1 for 12 hours (12:12 LDC). Cell growth was measured by counting the cell numbers using Sedgewick-Rafter cell on every one-day interval. Result of the experiment indicated that the growth of Pbc is significantly affected (p=0.02) by the concentration of soil extract. The fastest growth rate (0.287 K-1) with doubling rate of 0.384 d-1 was recorded in the culture with addition of 14% soil extract.