Studies on the Releasing and Recovery of Okadaic Acid in the Culture of Prorocentrum lima
Date Issued
2010
Date
2010
Author(s)
Lee, Ming-Chieh
Abstract
This study attempted to recover the released okadaic acid (OA) from the cultures of P. lima and improve the methodology of OA isolation. In P. lima culture, we found that OA was released and accumulated in the medium as mentioned elsewhere and in our previous studies. Thus, in order to enhance the OA production through the recovery from medium, high cell-density (over 105 cells/mL) cultures of P. lima were obtained by settling down the cells and replacing the old medium with fresh one. Treatments, such as increasing of vibration or aeration were found no enhancement in OA releasing rate of the cultured cells. It was found after a two-week period of static treatment of a culture in stationary phase, cells continuously released OA, and the releasing rate was even higher while comparing that with the vibration-treated culture at the same status. This result demonstrated that OA releasing in P. lima was spontaneous and was not as a result of stimulation from shaking or aerations reported elsewhere. It also showed that high concentration of extracellular OA did not affect the growth of P. lima cells, but inhibited the releasing of OA. In a medium of low extracellular OA content (0.51±0.03 mg/L), PL03 released OA at a higher rate (0.54±0.19 pg/cell/day) than that (0.02±0.12 pg/cell/day) of the cells maintained in a medium of higher extracellular OA (3.74±0.2 mg/L). The amount of OA released in high cell-density culture was substantially enormous. The revovery of OA from media was done by SP825 adsorption which was performed by a flow of medium through a column of 25 g SP825. Various flow rates had been tested for optimization and a capacity more than 10 mg OA/g SP825 was observed. The adsorbed toxin was easily eluted at a recovery of 97.35% by methanol using Soxlet reflux. The recovered crude extract was subjected for further CombiFlash column (Si) chromatographic separation to reach a purity more than 90% in the fractions collected. This study explored the releasing of OA in P. lima and established some parameters of OA recovery methodology for the future commercial production.
Subjects
Prorocentrum lima
Okadaic Acid
Type
thesis
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