Uptake of Inorganic and Organic Nitrogen Sources by Dinophysis acuminata and D. acuta

Type Article
Date 2020-02
Language English
Author(s) García-Portela Maria1, Reguera Beatriz1, Gago Jesus1, Le Gac MickaelORCID2, Rodríguez Francisco1
Affiliation(s) 1 : Spanish Institute of Oceanography (IEO), Oceanographic Center of Vigo, Subida a Radio Faro 50, Cabo Estay, Canido, 36390 Vigo, Spain
2 : Ifremer, DYNECO PELAGOS, 29280 Plouzané, France
Source Microorganisms (2076-2607) (MDPI AG), 2020-02 , Vol. 8 , N. 2 , P. 187 (14p.)
DOI 10.3390/microorganisms8020187
Note This article belongs to the Section Environmental Microbiology)
Keyword(s) Dinophysis, nitrate, ammonium, urea, uptake rates, N-15 incubations, antibiotic treatment
Abstract

Dinoflagellate species of Dinophysis are obligate mixotrophs that require light, nutrients, and prey for sustained growth. Information about their nitrogenous nutrient preferences and their uptake kinetics are scarce. This study aimed to determine the preferred nitrogen sources in cultures of D. acuminata and D. acuta strains from the Galician Rías Baixas (NW Spain) and to compare their uptake kinetics. Well-fed versus starved cultures of D. acuminata and D. acuta were supplied with N15 labeled inorganic (nitrate, ammonium) and organic (urea) nutrients. Both species showed a preference for ammonium and urea whereas uptake of nitrate was negligible. Uptake rates by well-fed cells of D. acuminata and D. acuta were 200% and 50% higher, respectively, than by starved cells. Uptake of urea by D. acuminata was significantly higher than that of ammonium in both nutritional conditions. In contrast, similar uptake rates of both compounds were observed in D. acuta. The apparent inability of Dinophysis to take up nitrate suggests the existence of incomplete nitrate-reducing and assimilatory pathways, in line with the paucity of nitrate transporter homologs in the D. acuminata reference transcriptome. Results derived from this study will contribute to understand Harmful Algal Blooms succession and differences in the spatio-temporal distribution of the two Dinophysis species when they co-occur in stratified scenarios.

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