Influence of biotic and abiotic factors on prymnesin profiles in three strains of Prymnesium parvum

Harmful algal blooms of Prymnesium parvum have resulted in significant fish kill events globally. These haptophytes produce the ichthyotoxic prymnesins, large polyethers categorized into A-, B- and C-types based on their carbon backbones with several analogs varying by the degree of glycosylation, chlorination, and double bonds. However, the influence of various biotic or abiotic factors on prymnesin profiles remains unknown. We investigated the influence of growth phase, nitrogen availability, light intensity, and salinity on prymnesin profiles of three P. parvum strains (UTEX-2797, K-0374 and PPSR01). Strains were selected based on their chemotypic expression of the three prymnesin backbones. Results demonstrated that different growth conditions led to strain-specific changes in prymnesin profiles. In the stationary phase, increased glycosylation was observed compared to the exponential growth phase for all strains. Additionally, at early stationary phase the trichlorinated analogs represented >90 % of all prymnesins of P. parvum strains UTEX-2797 and PPSR01 when cultured at salinity of 10 psu. By gaining an understanding of the effects of biotic and abiotic factors, culture conditions could be modified to promote specific prymnesin profiles to support the development of analytical reference materials. Furthermore, evaluating prymnesin profiles in combination with toxicity assays will provide insights into prymnesin biosynthesis, mode of action and toxicity.