Nitrate Reductase Inhibition Induces Lipid Enhancement of Dunaliella Tertiolecta for Biodiesel Production

Abstract

Nitrogen stress increases lipids content in microalgae, the main feedstock for algal biodiesel. Sodium tungstate was used in this study to implement nitrogen stress by inhibiting nitrate reductase (NR) in Dunaliella tertiolecta. The reduction of NR activity was accompanied by reduction of chlorophyll and accumulation of lipids. One-stage and two-stage culture strategies were compared. One-stage culture raised total lipids from 18% (control) to 39% (w: w); however, two-stage culture raised lipids to 50% in which neutral lipids were enhanced 2.14 times. To assess the quality of biodiesel produced, fatty acid methyl esters (FAME) composition was studied. It showed a slight variation of unsaturation. In addition, some physical proprieties of biodiesel were estimated and showed that higher heating values were improved by tungstate treatment. In this study, we tried to shed light on some biological impact of NR inhibition in microalgae cells using sodium tungstate which could be exploited in the improvement of biodiesel production.

Effect of Nitrogen Sources on Omega-3 Polyunsaturated Fatty Acid Biosynthesis and Gene Expression in Thraustochytriidae sp.

“…In the study of Benhima et al, sodium tungstate was used to inhibit NR in microalgae Dunaliella tertiolecta, resulting in a 50% increase of neutral lipids. Besides, fatty acid methyl esters composition showed a slight variation of polyunsaturation and elongation [59]. McCarthy et al found that the knockout (KO) of NR gene impacted the lipids metabolism in model pennate diatom Phaeodactylum tricornutum.…”

Pb(II)-phycoremediation mechanism using Scenedesmus obliquus: cells physicochemical properties and metabolomic profiling

“…Several microalgae species have been reported to have a strong capacity to accumulate lipid bodies under various stress conditions ( Sarkar et al., 2021 ). Neutral lipids are part of the essential components of membranes such as glycol and phospholipids ( Benhima et al., 2018 ). In this study, the enhancement of natural lipids content in Pb(II)-loaded cells might be an adaptation mechanism against the oxidative stress caused by Pb(II) ions in the intracellular compartment.…”

Use of <em>Dunaliella salina</em> in Environmental Applications <sup>†</sup>

“…Biofuel production from microalgae consists of four steps: isolation, characterization, biomass production, and harvesting. Today, D. salina and other microalgae are used as a raw material source for many types of biofuels, such as the production of biogas by anaerobic degradation of biomass, biodiesel production from oil content (D. salina: 116 mg/L oil productivity), and biohydrogen production by photo-biological reactions [51,52].…”