title: Evaluation of the production of paralytic shellfish poisoning toxins by extracellular bacteria isolated from the toxic dinoflagellate Alexandrium minutum.
abstract: The purpose of the study was to determine if paralytic shellfish poisoning (PSP) toxins are present in extracellular bacteria isolated from a toxic strain of the dinoflagellate Alexandrium minutum. A quantitative analysis was carried out of viable culturable bacteria attached to the surface of dinoflagellates and of bacteria present in dinoflagellate culture medium. A numerical taxonomy study was undertaken for presumptive identification of bacteria attached to the surface of dinoflagellates. Members of the following genera were detected on the cell surface of A. minutum: Cellulophaga, Marinomonas, Pseudoalteromonas, and Vibrio. The presence of intracellular PSP toxins in bacteria isolated from the cell surface of dinoflagellates was analysed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Compounds that eluted at the same time as the standards of the PSP toxins GTX-2, GTX-3, GTX-4, dcGTX-2, and dcGTX-3 were present in some of the bacterial cell extracts. Natural fluorescent bacterial compounds, coeluting with some PSP toxins, were also detected. The results obtained showed that the fluorescent compounds, identified as putative PSP toxins by HPLC-FLD, did not correspond to any PSP analogue. This allowed us to reject the hypothesis that extracellular bacteria attached to the surface of dinoflagellates produce PSP toxins.
authors.affiliation: Departamento de Bioloxia Funcional e Ciencias da Saude, Universidade de Vigo, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Prol
authors.forename: Cástor
authors.initials: C
authors.lastname: Guisande
authors.forename: Aldo
authors.initials: A
authors.lastname: Barreiro
authors.forename: Beatriz
authors.initials: B
authors.lastname: Míguez
authors.forename: Pablo
authors.initials: P
authors.lastname: de la Iglesia
authors.forename: Adriano
authors.initials: A
authors.lastname: Villar
authors.forename: Ana
authors.initials: A
authors.lastname: Gago-Martínez
authors.forename: María Pilar
authors.initials: MP
authors.lastname: Combarro
mesh_terms: D056893:Alveolata / Q000737:chemistry* / Q000378:metabolism / Q000382:microbiology*; D002851:Chromatography, High Pressure Liquid; D005110:Extracellular Space / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D008387:Marine Toxins / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D013058:Mass Spectrometry
chemical_list: D008387:Marine Toxins