Comparison of paralytic shellfish toxin (PST) production by the dinoflagellates Alexandrium lusitanicum NEPCC 253 and Alexandrium tamarense NEPCC 407 in the presence and absence of bacteria

Hold, G. L., Smith, E. A., Birkbeck, T. H. and Gallacher, S. (2001) Comparison of paralytic shellfish toxin (PST) production by the dinoflagellates Alexandrium lusitanicum NEPCC 253 and Alexandrium tamarense NEPCC 407 in the presence and absence of bacteria. FEMS Microbiology Ecology, 36(2-3), pp. 223-234. (doi: 10.1111/j.1574-6941.2001.tb00843.x)

Abstract

The ability of two <i>Alexandrium</i> species to produce paralytic shellfish toxins (PST) in laboratory culture following the generation of bacteria-free cultures was investigated. The dinoflagellates <i>Alexandrium lusitanicum</i> NEPCC 253 and <i>Alexandrium tamarense</i> NEPCC 407 were cultured in the presence of antibiotics and tested for residual bacteria. After treatment with a cocktail of streptomycin, ciprofloxacin, gentamicin and penicillin G, bacteria could not be detected in either of the treated <i>Alexandrium</i> cultures using 17 different solid and broth bacterial growth media, by epifluorescence microscopy with the dye Sybr green 1, or polymerase chain reaction amplification using universal eubacterial primers designed to target the 16S rRNA gene. Subsequent analysis of <i>A. Lusitanicum</i> for PST using high performance liquid chromatography demonstrated that the growth rate and toxin profile remained similar in both bacteria-free and control cultures, although the quantity of toxins produced differed with the bacteria-free culture producing generally more of each compound and also having a greater toxin content in terms of saxitoxin equivalents. <i>A. Tamarense</i> also retained similarities between the bacteria-free and control cultures in terms of growth rates and toxin profile, although in this instance, depending on the growth stage and the toxin, the control culture produced more of some toxins than the bacteria-free culture. The control culture was also more toxic in terms of saxitoxin equivalents than the axenic culture. These results suggest that bacteria can influence toxin production in laboratory cultures of <i>Alexandrium</i> species although the mechanisms remain unknown.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Birkbeck, Professor Harry
• Authors: Hold, G. L., Smith, E. A., Birkbeck, T. H., and Gallacher, S.
• College/School: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Journal Name: FEMS Microbiology Ecology
• Publisher: Wiley
• ISSN: 0168-6496
• ISSN (Online): 1574-6941
• Published Online: 05 January 2006