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Applied and Environmental Microbiology, January 2003, p. 659-662, Vol. 69, No. 1
0099-2240/03/$08.00+0     DOI: 10.1128/AEM.69.1.659-662.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Effect of Associated Bacteria on the Growth and Toxicity of Alexandrium catenella

Paulina Uribe1 and Romilio T. Espejo2*

Laboratorio de Bioingeniería, Instituto de Nutrición y Tecnología de los Alimentos,2 Laboratorio de Toxinas Marinas, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Chile1

Received 13 May 2002/ Accepted 3 October 2002

Saprophytic bacteria in cultures of the marine dinoflagellate Alexandrium catenella were removed to assess their effect on growth and paralytic shellfish poisoning toxin production of this dinoflagellate. The actual axenic status was demonstrated by the lack of observable bacteria both immediately after treatment and following extended incubation in the absence of antibiotics. Bacteria were measured by counting CFU and also by epifluorescence microscopy and PCR amplification of bacterial 16S-23S spacer ribosomal DNA to detect noncultivable bacteria. Removal of bacteria did not have any effect on the growth of the dinoflagellate except for the inhibition of A. catenella disintegration after reaching the stationary phase. Toxicity was determined in dinoflagellate cell extracts by different methods: high-performance liquid chromatography (HPLC); an electrophysiological test called the Electrotest, which measures the inhibition of saxitoxin-sensitive Na+ channels expressed in a cell line; and a mouse bioassay, which measures the toxic effect on the whole mammal neuromuscular system. A lower toxicity of the dinoflagellates in axenic culture was observed by these three methods, though the difference was significant only by the mouse bioassay and HPLC methods. Altogether the results indicate that axenic cultures of A. catenella are able to produce toxin, though the total toxicity is probably diminished to about one-fifth of that in nonaxenic cultures.

* Corresponding author. Mailing address: Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Macul 5540, Santiago, Chile. Phone: 56-2-6781426. Fax: 56-2-2214030. E-mail: respejo{at}uec.inta.uchile.cl.

Applied and Environmental Microbiology, January 2003, p. 659-662, Vol. 69, No. 1
0099-2240/03/$08.00+0     DOI: 10.1128/AEM.69.1.659-662.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Palacios, L., Marin, I. (2008). Enzymatic Permeabilization of the Thecate Dinoflagellate Alexandrium minutum (Dinophyceae) Yields Detection of Intracellularly Associated Bacteria via Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization. Appl. Environ. Microbiol. 74: 2244-2247 [Abstract] [Full Text]  
  • Ordas, M. C., Fraga, S., Franco, J. M., Ordas, A., Figueras, A. (2004). Toxin and molecular analysis of Gymnodinium catenatum (Dinophyceae) strains from Galicia (NW Spain) and Andalucia (S Spain). J PLANKTON RES 26: 341-349 [Abstract] [Full Text]  


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