Comprehensive metabolic reprograming in freshwater Nitzschia palea strains undergoing nitrogen starvation is likely associated with its ecological origin

Abstract

Nitrogen deficiency can increase the lipid content in certain microalgae species, including diatoms. However, the molecular and metabolic basis of such changes remains rather unclear. We analyzed strains of freshwater Nitzschia palea collected from a eutrophic pond and from an artificial rock. The habitats, differing in light and nutrient availability, lead to two metabolically distinct strains, BR006 and BR022. Differential accumulation of primary compounds, membrane lipid composition and fatty acid saturation were observed. Metabolic and biophysical analysis demonstrated differential sensitivity to N regimes: depleted, replete and saturated. Whereas N depletion leads to typical stress-related responses in both strains, including reduction of protein and photosynthesis, the response observed in BR006 is far more severe. Our results demonstrated that these strains developed distinct metabolic responses to N conditions. BR022 is able to maintain cellular homeostasis and slows down growth according to N availability. In contrast, BR006 maximizes growth rate even under N limitation, by triggering stress response, relocating carbon pool to lipid compounds and quickly reaching growth arrest after N exhaustion. We identified a relationship between habitat characteristics and metabolic responses, providing a metabolic perspective on ecological plasticity of N. palea, which helps it to survive a wide range of habitats.

Metabolites Re-programming and Physiological Changes Induced in Scenedesmus regularis under Nitrate Treatment

“…Spectra obtained from 1/4X NO 3 cultures were not as sharp as spectra obtained from other treatment cultures. Broad spectra are indicative of heavy molecular weight components inside the extract sample 15 , 33 , 34 . A possible higher relative concentration of sugar or starch granules (in comparison to other metabolites) may have accumulated within the microalgae cell as microalgae cells have been acknowledged to synthesis starch under nitrate starved conditions 8 , 35 , 36 .…”

“…Scenedesmus regularis (KS-MC1) was obtained from Institute of Marine Biotechnology (IMB) of Universiti Malaysia Terengganu. The culture and maintenance of Scenedesmus regularis was adopted from 34 . In nitrate treatment, the concentration for NaNO 3 was altered while the other components remained the same as in Guillard’s F2 media.…”

“…A total of 0.215 g of freeze-dried algal biomass was used for (homogenizer) extraction 34 . Extraction solvents were prepared by adding Chloroform (99% absolute chloroform, ACS grade) with aqueous solvent that prior mixed from 99% absolute methanol (ACS, ISO, Reag grade) and pure distilled water into 1:1 ratio.…”

“…The aqueous phase of extract was re-suspended in 600 µl of phosphate buffer (0.1 M, pH 7) containing 10% D 2 O and the chloroform phase extract was re-suspended in 600 µl of chloroform –d 99.8% containing 0.01% of sodium tetramethysilane (TMS). Both sample were then subjected to 10 min of 10,000 rpm centrifugation before transferred into 5 mm NMR tube 34 .…”

Influence of Nitzschia sp. on release of nitrogen and phosphorus from sediment in pond breeding sea cucumbers

“…Cladophora influences the process of P exchange in sediments in Rongcheng Swan Lake, and this can significantly promote the release of P from the sediment (Gao et al, ). Prior studies have also shown that microalgae can effectively utilise nutrients in the water, including N and P, aiding in their growth and reproduction (Machado et al, ). As such, it can be surmised that Nitzschia sp .…”