Salinity tolerance of four freshwater microalgal species and the effects of salinity and nutrient limitation on biochemical profiles

Abstract

Microalgae are ideal candidates for bioremediation and biotechnological applications. However, salinity and nutrient resource availability vary seasonally and between cultivation sites, potentially impacting on biomass productivity. The aim of this study was to screen pollutant-tolerant freshwater microalgae (Desmodesmus armatus, Mesotaenium sp., Scenedesmus quadricauda and Tetraedron sp.), isolated from Tarong power station ash-dam water, for their tolerance to cultivation at a range of salinities. To determine if biochemical composition could be manipulated, the effects of 4-day nutrient limitation were also determined. Microalgae were cultured at 2, 8, 11 and 18 ppt salinity, and nutrient uptake was monitored daily. Growth, total lipid, fatty acid (FA), and amino acid contents were quantified in biomass harvested while nutrient-replete and, after 4 days, nutrient-deplete. D. armatus showed the highest salinity tolerance actively growing in up to 18 ppt while Mesotaenium sp. was the least halotolerant with decreasing growth rates from 11 ppt. However, Mesotaenium sp. at 2 and 8 ppt had the highest biomass productivity and nutrient requirements of the four species, making it ideal for nutrient remediation of eutrophic freshwater effluents. Salinity and nutrient status had minimal influence on total lipid and FA contents in D. armatus and Mesotaenium sp., while nutrient depletion induced an increase of total lipid and FAs in S. quadricauda and Tetraedron sp., which was further increased with increasing salinity. As none of the growth conditions affected amino acid profiles of the species, these findings provide a basis for species selection based on site-specific salinity conditions and nutrient resource availability.

Evidence of early deglaciation (18 000 cal a bp) and a postglacial relative sea‐level curve from southern Karmøy, south‐west Norway

“…We approached this issue by: (i) analysing samples from the till at the base of core 507‐05 to establish which taxa were potentially available for reworking from surrounding till deposits during the Lateglacial, and (ii) registering the total fraction of fragmented phytoplankton specimens in all samples from Grødheimsvatnet. Some brackish‐water dinoflagellate species are known to produce resting cysts that can be preserved in palynological samples (Wall et al , ), and some taxa of Chlorococcales can tolerate salinities in the range 3–8‰ (Mur, ; Rao et al , ; Yoshimura et al , ; von Alvensleben et al , ). However, for simplicity we refer to dinoflagellate cysts as marine taxa and the Chlorococcales as freshwater taxa in the main text and figures.…”

Effects of temperature, salinity and composition of the dinoflagellate assemblage on the growth of Gambierdiscus carpenteri isolated from the Great Barrier Reef

“…Low growth in response to environmental stressors, such as warmer temperatures and changes in salinity can be explained by higher metabolic costs and potential for photoinhibition (Rosic et al, 2011). Changes in salinity are likely to initiate osmolyte production (von Alvensleben et al, 2016) and fine-tuning of expression of various heat shock proteins (HSPs) (Rosic et al, 2011), with both survival strategies incurring metabolic cost (Kibler et al, 2012). For example, reduced salinity could cause a cell's internal K + /Na + pump to be more frequently engaged to modify cell size and/or turgor (von Alvensleben et al, 2016).…”

“…Changes in salinity are likely to initiate osmolyte production (von Alvensleben et al, 2016) and fine-tuning of expression of various heat shock proteins (HSPs) (Rosic et al, 2011), with both survival strategies incurring metabolic cost (Kibler et al, 2012). For example, reduced salinity could cause a cell's internal K + /Na + pump to be more frequently engaged to modify cell size and/or turgor (von Alvensleben et al, 2016). Variable expression of HSPs has been well studied in corals due to concerns over consequences of increased SSTs (Rosic et al, 2011).…”

Effect of Temperature-induced Two-stage Cultivation on the Lipid and Saccharide Accumulation of Microalgae Chlorella vulgaris and Dunaliella salina

“…(Chen et al, 2011;Baicha et al, 2016;Yang et al, 2016). , , Goold et al, 2016;Kinnunen and Rintala, 2016;von Alvensleben et al, 2016). 2 (Su et al, 2011;Zheng et al, 2012;dos Santos et al, 2016 Su et al, 2011;Xia et al, 2013;Zheng et al, 2012;dos Santos et al, 2016).…”