Effect of different nitrogen/phosphorus nutrient ratios on the toxin content in Alexandrium minutum

Abstract

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 20:157-165 (1999) - doi:10.3354/ame020157 Effect of different nitrogen/phosphorus nutrient ratios on the toxin content in Alexandrium minutum Christian Béchemin1,*, Daniel Grzebyk1, Fatima Hachame1, Christian Hummert2, Serge Y. Maestrini1 1Centre de Recherche en Ecologie Marine et Aquaculture de L'Houmeau (CNRS-IFREMER), BP 5, 17137 L'Houmeau, France 2Institute of Nutrition and Environment, University of Jena, Dornburger Str. 25, 07743 Jena, Germany *E-mail: cbechemi@ifremer.fr ABSTRACT: Alexandrium minutum (strain AM89BM) was grown in semi-continuous culture (0.2 volume d-1) in N-limiting (NO3:PO4 = 1.6 and 3.16), in P-limiting (N:P = 160 and 80), and in N- and P-balanced (N:P = 16) media. Daily supplies of limiting nutrients were taken up until exhaustion; most residual concentrations before renewal were near the detection limits. Samples were taken during 2 separate periods: Days 5 to 12 and 26 to 36. During both periods, cells grew at the real rates of 0.23 division d-1 in the N:P balanced medium, while the growth rate was decreased in all N:P <16 or >16 media during the first period, and only in the N:P = 1.6 medium during the second period. Cells grown in N-limiting media contained 1/3 less PON and 1/2 less chlorophyll a than cells grown in the N:P balanced condition. The POP content per cell did not vary significantly. In contrast, PON:POP ratios in cells grown in P-limiting conditions were over 50. Thus, cells grown in the 2 N:P <16 conditions were nitrogen-deficient, while cells grown in N:P = 80 and 160 conditions were nitrogen-surfeit. The toxin content in cells greatly changed according to the N:P regime. Cells grown at N:P balanced conditions showed an average total paralytic shellfish poisoning (PSP) content of 1.24 fmol cell-1. In N-limiting conditions, cells contained ca 3 times less toxin, with mean values of 0.41 to 0.45 fmol cell-1. In contrast, cells grown in P-limiting conditions contained on average 3.5 and 7 times more toxins than under balanced N:P conditions; 4.31 fmol cell-1 in the N:P = 160 medium and 8.01 fmol cell-1 in the N:P = 80 medium. KEY WORDS: Alexandrium minutum · Toxin content · PSP · Nitrogen deficiency · Nitrogen excess Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 20, No. 2. Publication date: December 15, 1999 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1999 Inter-Research.