Ecophysiological and biochemical variation of the surf zone diatom asterionellopsis glacialis sensu lato from Santa Catarina, Southern Brazil

Abstract

Patches formed by dense accumulations of diatoms in the surf zone (surf diatoms) are common on sandy beaches with intermediate to dissipative morphodynamic states. Their appearances are correlated with environmental factors such as the passage of cold fronts when onshore winds increase beach hydrodynamics, resuspending epibenthic stocks and accumulating them through the inner surf zone. In Santa Catarina state, Southern Brazil, two beaches are known to have frequent occurrence of accumulations of the surf diatom Asterionellopsis glacialis sensu lato: Rincão Beach (28°50' S) and Navegantes Beach (26°52' S). The high biomass of this alga and its central importance in the trophic structure of the coastal ecosystems suggest studies about its potential applications. In the present study, strains of A. glacialis were isolated, cultured under different conditions and evaluated for ecophysiological aspects: growth rate under different conditions, potential biological activities of exudates, biomass and lipid content, and fatty acid profile. A. glacialis cells in culture showed deformation, which were ameliorated by using agitation and silicon and phosphorus enriched culture media. Exudates of the strains showed no allelopathic effects, although previous studies have indicated activity. Lipid content showed variation depending on the strain and culture media. Values ranged from 9% to 13.6% by dry weight. In all strains saturated fatty acids and polyunsaturated fatty acids were identified. Some hypotheses were proposed to explain the variation of the lipid contents, fatty acid profiles and physiological features between strains of the same species. We believe that the fatty acids profile of this primary producer has important consequences in the sandy beach ecology.

Transcriptome Sequencing of the Diatom Asterionellopsis thurstonii and In Silico Identification of Enzymes Potentially Involved in the Synthesis of Bioactive Molecules

“…Saturated and polyunsaturated fatty acids (PUFA) have also been found in some strains of Asterionellopsis glacialis sensu lato (s.l. ), as shown in the work of Viso et al [ 30 ] and Rörig et al [ 29 ]. Various Asterionellopsis strains may also have a different content of lipids and fatty acids related to genetic and chemical diversity of strains [ 21 , 29 ].…”

“…), as shown in the work of Viso et al [ 30 ] and Rörig et al [ 29 ]. Various Asterionellopsis strains may also have a different content of lipids and fatty acids related to genetic and chemical diversity of strains [ 21 , 29 ]. In addition, Shibl et al [ 31 ] also showed that A. glacialis reprogrammed its transcriptional and metabolic profile in the presence of bacteria, secreting a series of primary metabolites and two unusual metabolites, rosmarinic acid and azelaic acid [ 31 ].…”

“…In 2005, Wichard and collaborators showed the presence of PUAs in Asterionellopsis glacialis [ 24 ], known to reduce reproductive success of copepods and other invertebrates and to induce allelopathic effects on other phytoplankton species and variations in the community composition of picoplankton, with possible consequences on the marine food web structure [ 25 , 26 , 27 , 28 ]. Rörig et al [ 29 ] found difficulties in Asterionellopsis cultivation, showing that the strains, after weeks or months of laboratory culturing, started losing their viability and presented aberrant frustules. They suggested a reduction in nutrients or a low quantity of salts in the culture medium as possible causes for these effects [ 29 ].…”

“…Rörig et al [ 29 ] found difficulties in Asterionellopsis cultivation, showing that the strains, after weeks or months of laboratory culturing, started losing their viability and presented aberrant frustules. They suggested a reduction in nutrients or a low quantity of salts in the culture medium as possible causes for these effects [ 29 ]. Saturated and polyunsaturated fatty acids (PUFA) have also been found in some strains of Asterionellopsis glacialis sensu lato (s.l.…”