Morphology, biochemistry and growth of Raphidophyte strains from the Gulf of California

Abstract

Strains of raphidophytes from differentregions of the Gulf of California were established foridentification and biochemical description. Raphidophytein our coasts have been traditionally identifiedbased on microscopic observations, a biochemicalanalyses of strains present in our coast is needed for amore detailed characterization and species confirmation.Strains were identified by morphological observationsand sequencing of the 5.8S and COI regions.Cells were cultivated in modified f/2 media at 20 Cwith a light–dark cycle (12 h:12 h) and 150 lmolm-2 s-1 light intensity. Pigments were identified byHPLC, brevetoxins by LC–MS/MS, fatty acids by gaschromatography, superoxide radicals by spectrophotometry,and lipid peroxidation by the determinationof thiobarbituric acid reactive substances. Strainswere identified as Chattonella subsalsa, C. marina,and Fibrocapsa japonica. In all strains, the mainpigment was chlorophyll a, followed by fucoxanthin,chlorophyll c1 and c2, violaxanthin, b-carotene, anddiadinoxanthin. Strains were tested for PbTx-1, PbTx-2, PbTx-3, PbTx-6, PbTx-9, PbTx-carboxylic acid,brevenal, and brevisin; none were detected. All strainspresented superoxide radical production and lipidperoxidation. The main fatty acids were 18:4 (n-3) and20:5 (n-3). Strains had typical fatty acid compositionfor raphidophytes and produced brevetoxin-like compounds,had superoxide radical production, and lipidperoxidation. With this contribution, we confirm thepresence of C. subsalsa,