Growth and toxin production of the toxic dinoflagellate Pyrodinium bahamense var. compressum in laboratory cultures

Abstract

Toxin production of a Malaysian isolate of the toxic red tide dinoflagellate Pyrodinium bahamense var. compressum was investigated at various stages of the batch culture growth cycle and under growth conditions affected by temperature, salinity, and light intensity variations. In all the experiments conducted, only 5 toxins were ever detected. Neosaxitoxin (NEO) and gonyautoxin V (GTX5) made up 80 mole percent or more of the cellular toxin content and saxitoxin (STX), GTX6 and decarbamoylsaxitoxin (dcSTX) made up the remainder. No gonyautoxins I-IV or C toxins were ever detected. In nutrient-replete batch cultures, toxin content rapidly peaked during early exponential phase and just as rapidly declined prior to the onset of plateau phase. Temperature had a marked effect on toxin content, which increased 3-fold as the temperature decreased from the optimum of 28 degrees C to 22 degrees C. Toxin content was constant at salinities of 24% or higher, but increased 3-fold at 20%. Toxin content decreased 2-fold and chlorophyll content increased 3-fold when light intensity was reduced from 90 to 15 microE m-2 s-1. This accompanied a 30% decrease in growth rate. Toxin composition (mole % individual toxin cell-1) remained constant throughout the course of the nutrient-replete culture and during growth at various salinities, but varied significantly with temperature and light intensity changes. At 22 degrees C, GTX5 was 25 mole % and NEO was 65 mole %, while at 34 degrees C, GTX5 increased to 55 mole % and NEO decreased proportionally to 40 mole %. When light intensity was reduced from 90 to 15 microE m-2 s-1, NEO decreased from 55 to 38 mole %, while GTX5 increased from 40 to 58 mole %. These data suggest that low light and high temperature both somehow enhance sulfo-transferase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Global change and the future of harmful algal blooms in the ocean

“…These temperature tolerances support po tential climate-related range expansion (Usup et al 2012). Although the majority of environmental variables examined influence the PSP toxin profile, not total toxin content, one study demonstrated increased toxicity at low temperature (Usup et al 1994).…”

“…Paz et al (2007) also reported that yessotoxin production decreased with increasing salinity in this species. Toxicity in this species was demonstrated to be relatively unchanged above sal inity 24, but was enhanced 3-fold at salinity 20 (Usup et al 1994). Karenia brevis is thought to tolerate a range of salinities (18−45) but seems to grow best in full-salinity seawater (Magana & Villareal 2006, Brand et al 2012).…”

Toxin variability during the cell cycle of the dinoflagellate Alexandrium fundyense

“…This interprctation has to be carefully contrasted with observations of changes and variations in toxin composition in other dinoflagellate species such as Pyrodinium bahamense and Gymnodinium catenatum (Oshima et al 1993;Usup et al 1994). In these organisms, STX has been postulated to be a precursor or parent compound that is rapidly converted into NE0 or GTXS, as these last two compounds are predominant and only negligible amounts of STX are detected (Oshima et al 1993;Usup et al 1994). In an integrated sheme of the STX biosynthetic pathway, interconversions among the toxins would be determined in part by the presence or absence of the appropriate enzymes, but actual toxin production would be the result of the accumulation of only one precursor or parent compound.…”

“…The extracts were stored at -20°C before analysis. The extracts were analyzed by HPLC (Oshima et al 1989) incorporating the modifications previously described by Anderson et al (1994).…”

Responses of Pyrodinium bahamense var. compressum and associated cultivable bacteria to antibiotic treatment

“…compressum clone originating from the same site in the Philippines, PBC-MZ-061,593, whose growth rate (k) ranged from 0.2 to 0.3 div d −1 (Gedaria et al 2007). An isolate from Sabah, Malaysia had a faster growth rate (k) of 0.3-0.4 div d −1 (Usup et al 1994). Environmental and possibly genetic factors may explain this variability.…”