Nitrogen and phosphorus limitation in cultured Alexandrium minutum Halim does not promote toxin production

Abstract

Studies of a high- and low-toxin strains of Alexandrium minutum isolated from Ría de Vigo fail to indicate profound C-N pbysiology differences in amino acid synthesis, biomass, growth rates or pigmentation, which might explain the 10 to 20 fold differences in PSP toxin content. Maximum toxin synthesis occurs during N-refeeding of N-deprived cells and thereafter toxin content covaries with free intracellular arginine. For both strains, toxin synthesis and toxin content on a cell or biomass basis decline during N or P deprivation. Implications for changes in the toxin content of field populations are discussed.