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VARIABLE BREVETOXIN PRODUCTION IN GYMNODINIUM BREVE ATTRIBUTABLE TO GROWTH CONDITIONS AND STRAIN DIFFERENCES
Citation:
Greene, R M., J C. Kurtz, R S. Stanley, C A. Chancy, M C. Murrell, F J. Genthner, J E. Rogers, AND C C. Walker. VARIABLE BREVETOXIN PRODUCTION IN GYMNODINIUM BREVE ATTRIBUTABLE TO GROWTH CONDITIONS AND STRAIN DIFFERENCES. Presented at Symposium on Harmful Marine Algae in the U.S, Woods Hole, MA, 5-9 December 2000.
Description:
Blooms of the dinoflagellate Gymnodinium breve can produce sufficient concentrations of brevetoxin to negatively impact coastal ecosystems, human health, and local economies. Assessment of risks associated with G. breve blooms and subsequent brevetoxin exposure requires better understanding of factors governing bloom developoment and toxin production. Although the complete biosynthetic pathway for brevetoxin has not been elucidated, reports in the literature suggest some degree of geographic or strain-specific variability in total cellular brevetoxin concentration, ranging from 7 to 17 pg cell-1 (Baden and Tomas, 1988; Hua et al., 1996).
During Fall 1999, a G. breve bloom impacted a 150 mile stretch of the Florida panhandle shoreline. In samples collected from 16 locations on 3 fall sampling dates, G. breve abundance ranged from 0.1 - 20 x 106 L-1. Using HPLC methods, we measured total brevetoxin (PbTx 1, 2, 3, 6) concentrations that greatly exceeded those reported in the literature. In shelf waters off Pensacola and Navarre beaches and in estuarine waters of Cinco Bayou and Santa Rosa Sound, total brevetoxin ranged from 47 to 67 pg cell-1 (n=5), 59 to 126 pg cell-1 (n=3), and 12 to 63 pg cell-1 (n=8), respectively.
Brevetoxin production and accumulation in response to nitrogen, phosphorus, and light availability were examined in laboratory cultures using three G. breve strains; the Piney Island (courtesy of FMRI) and Charlotee Harbor (courtesy of NOAA) strains isolated from the central west Florida coast, and the Pensacola Beach strain (EPAJR1) isolated from the Fall 1999 panhandle bloom. When grown under standard conditions with f/2 nutrient concentrations, total brevetoxin concentrations in Piney Island and Charlotte Harbor strains ranged from 10 to 20 pg cell-1, whereas the Pensacola Beach strain produced about 30 pg cell-1 five months following isolation. However, by reducing nitrate (<10 ?M) or phosphate (<0.6 ?M), by substituting urea (<5 ?M), or by loweri