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

• Published in: FEMS microbiology ecology 2001-07, Vol.36 (2/3), p.223-234
• Main Authors: Hold, G.L, Smith, E.A, Birkbeck, T.H, Gallacher, S
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Alexandrium; Alexandrium lusitanicum; Alexandrium tamarense; Antibiotics; Axenic culture; Bacteria; benzylpenicillin; Biological and medical sciences; Ciprofloxacin; Culture media; developmental stages; Dinoflagellata; Dinoflagellate; Dinoflagellates; Ecology; Economic plant physiology; Epifluorescence microscopy; Equivalence; fluorescence microscopy; Fundamental and applied biological sciences. Psychology; genes; Genetics and breeding of economic plants; Gentamicin; Growth media; Growth rate; Growth stage; High performance liquid chromatography; High performance liquid chromatography (HPLC); Laboratories; Laboratory culture; Liquid chromatography; microbial growth; Microbiology; Microorganisms; Paralytic shellfish toxin (PST); Penicillin; Pest animals; Pest resistance; Polymerase chain reaction; Polymerase chain reaction (PCR); Pure culture; ribosomal RNA; rRNA 16S; Saxitoxin; Shellfish; Streptomycin; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); toxicity; Toxins; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2001.tb00843.x

The ability of two Alexandrium species to produce paralytic shellfish toxins (PST) in laboratory culture following the generation of bacteria-free cultures was investigated. The dinoflagellates Alexandrium lusitanicum NEPCC 253 and Alexandrium tamarense 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 Alexandrium 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 A. lusitanicum 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. A. tamarense 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 Alexandrium species although the mechanisms remain unknown.