Contaminant-free cultivation of Pfiesteria shumwayae (Dinophyceae) on a fish cell line

Abstract

Geographically distinct strains of the heterotrophic dinoflagellate Pfiesteria shumwayae were cultivated on a fish cell line in the apparent absence of bacteria and other microbial conta- minants. Cultures were established with a high rate of success by inoculating single purified P. shumwayae cells into fish cell cultures containing a simple saltwater medium suitable for both cell types, and resulting isolates were serially cultivated on fish cells for months without visible signs of abnormality or reduced viability. P. shumwayae fed phagocytically on the fish cells and exhibited higher cell production than reported using other culturing methods. Compared to previous methods of studying the interaction between Pfiesteria spp. and fishes, this system enabled closer and more direct observation of the dinoflagellates and was also more economical and sustainable as a culturing method. The absence of bacteria and other contaminating microorganisms should facilitate important physiological and biochemical investigations. The methods used were inadequate for cultivating strains of P. piscicida, suggesting a possible difference in nutritional requirements between the 2 Pfiesteria species.