Development of a protein-free chemically defined culture medium for the propagation of the oyster pathogen Perkinsus marinus

In the present study we describe a protein-free, chemically defined culture medium, designated JL-ODRP-3, which supports the propagation of Perkinsus marinus, a parasite of the eastern oyster, Crassostrea virginica. P. marinus adapted rapidly to the defined medium and the growth rate of the protozoan increased significantly following a few subcultures. Two isolates of P. marinus, one from the Chesapeake Bay (Virginia) and the other from the Gulf of Mexico (Texas) were cultured for at least ten passes. The doubling times for the isolates from Virginia and Texas, in log phase, were 18 ± 1.2 and 28.6 ± 3.2 hours respectively, after ten passes in JL-ODRP-3. Moreover, P. marinus cells cultured in the defined medium were infective to eastern oysters. Finally, the defined medium was used successfully to initiate continuous cultures of P. marinus from heart fragments of infected oysters. The absence of proteins and peptides from this chemically defined medium demarcates JL-ODRP-3 as the most suitable medium to study P. marinus proteins, to produce antigens for antibody production, and to screen chemotherapeutic agents