Effect of the deficiency of nitrate and silicate on the growth and composition of the benthic diatom Navicula incerta

Abstract

Navicula incerta is a benthic diatom with potential use in nutrition and health for humans and aquaculture. Therefore, it is important to know its optimal growth conditions and biochemical composition. In this study, the effects of nitrate and silicate concentration on the growth kinetics and biochemical composition of N. incerta under laboratory conditions were measured. F/2 media was used as the control, and different concentrations of nitrogen (N/4, N/8 and N/16) and silicates (Si/4, Si/8 and Si/16) were evaluated. We measured cell concentration, chlorophyll-a and conducted proximal chemical analyses. It was found that different concentrations of nutrients affected the diatom’s growth kinetics and affected the concentrations of ash, chlorophyll, protein, lipids and carbohydrates. The highest concentration of lipids was obtained in the limiting treatment of nitrogen N/8 (27.09%), while the lowest value was found with silicate Si/8 media (16.97%). Carbohydrates increased compared to the control, with the N/16 treatment presenting the maximal concentration (23.31%). Treatments with reduced nitrate (N/8 and N/16) demonstrated the lowest concentrations of protein (18.75 and 12.44%, respectively), while in reduced silicate treatments, no statistical differences (P ≥ 0.05) were observed. Therefore, media limited nitrogen and silicates affected the growth kinetics and proximal chemical composition of N. incerta. The growth of this species using the N/8 medium is a suitable method for increasing lipid concentration in N. incerta.

Enhancement of Biomass Production of Diatom Nitzschia sp. S5 through Optimisation of Growth Medium Composition and Fed-Batch Cultivation

“…Similar results were reported by other authors suggesting that under phosphorus starvation conditions, synthesis of proteins would continue if a nitrogen source was available, at least during the early exponential phase [ 46 , 48 , 49 , 50 ]. Higher carbohydrate and lipid levels are reported for cultivations supplemented with carbon source, especially CO 2 .…”

“…Lipid content in Nitzschia sp. S5 was comparable with values reported for Navicula incerta and Nitzschia inconspicua [ 46 , 47 ].…”

“…Lipid content in Nitzschia sp. S5 was comparable with values reported for Navicula incerta and Nitzschia inconspicua [46,47]. Contrary to several published studies, silicon deficiency in this work did not stimulate the synthesis of lipids in Nitzschia sp.…”

Enhancement of Biomass Production in Colony-Forming Green Algae, Botryosphaerella sudetica, Under Mixotrophic Cultivation

“…Previously, biotic and abiotic stresses were applied to green algae to enhance the lipid content of a limited available biomass (Rashid et al, 2020;Ananthi et al, 2021). For example, control of the nitrogen supply and type of sources (e.g., nitrate) increased the ratio of lipids to the weight unit (Dixit et al, 2020;Encinas-Arzate et al, 2020;Zhang et al, 2020). Nevertheless, increased lipid content was not accompanied by a positive effect on biomass productivity (Araujo et al, 2020;Toumi and Politaeva, 2021).…”

Uncovering the role of algal organic matter biocoating on Navicula incerta cell deposition and biofilm formation

“…This particular marine diatom not only serves as a significant contributor to marine biofilms in nutrient-rich water [ 12 ], but also exhibits high metabolic sensitivity toward detectable amounts of various organic and inorganic substances [ 13 ]. Under optimal condition, it is able to accumulate high level of lipid (25–40% dry cell weight) [ 14 , 15 ]. Therefore, it has the potential to be applied in nutrient recovery from nutrient rich waters while generating value-added bio-compounds.…”