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Applied and Environmental Microbiology, October 2007, p. 6410-6420, Vol. 73, No. 20
0099-2240/07/$08.00+0 doi:10.1128/AEM.01229-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Effect of Biotic and Abiotic Factors on In Vitro Proliferation, Encystment, and Excystment of Pfiesteria piscicida
,
Keiko Saito,
Tomás Drgon,
Danara N. Krupatkina,
Jana Drgonova,
Daniel E. Terlizzi,
Natalia Mercer,
and
Gerardo R. Vasta*
Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 East Pratt Street, Baltimore, Maryland 21202
Received 1 June 2007/ Accepted 6 August 2007
Pfiesteria spp. are mixotrophic armored dinoflagellates populating the Atlantic coastal waters of the United States. They have been a focus of intense research due to their reported association with several fish mortality events. We have now used a clonal culture of Pfiesteria piscicida and several new environmental isolates to describe growth characteristics, feeding, and factors contributing to the encystment and germination of the organism in both laboratory and environmental samples. We also discuss applied methods of detection of the different morphological forms of Pfiesteria in environmental samples. In summary, Pfiesteria, when grown with its algal prey, Rhodomonas sp., presents a typical growth curve with lag, exponential, and stationary phases, followed by encystment. The doubling time in exponential phase is about 12 h. The profiles of proliferation under a standard light cycle and in the dark were similar, although the peak cell densities were markedly lower when cells were grown in the dark. The addition of urea, chicken manure, and soil extracts did not enhance Pfiesteria proliferation, but crude unfiltered spent aquarium water did. Under conditions of food deprivation or cold (4°C), Pfiesteria readily formed harvestable cysts that were further analyzed by PCR and scanning electron microscopy. The germination of Pfiesteria cysts in environmental sediment was enhanced by the presence of live fish: dinospores could be detected 13 to 15 days earlier and reached 5- to 10-times-higher peak cell densities with live fish than with artificial seawater or f/2 medium alone. The addition of ammonia, urea, nitrate, phosphate, or surprisingly, spent fish aquarium water had no effect.
* Corresponding author. Mailing address: Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 East Pratt St., Baltimore, MD 21202. Phone: (410) 234-8826. Fax: (410) 234-8896. E-mail: vasta{at}umbi.umd.edu
Published ahead of print on 17 August 2007.
Supplemental material for this article may be found at http://aem.asm.org/.
Present address: National Institute on Drug Abuse, NIH, Baltimore, MD 21224.
Present address: Cátedra de Inmunología, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
Applied and Environmental Microbiology, October 2007, p. 6410-6420, Vol. 73, No. 20
0099-2240/07/$08.00+0 doi:10.1128/AEM.01229-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
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