Effect of Phytohormones Supplementation under Nitrogen Depletion on Biomass and Lipid Production of Nannochloropsis oceanica for Integrated Application in Nutrition and Biodiesel

Abstract

Economic viability of biodiesel production relies mainly on the productivity of biomass and microalgal lipids. In addition, production of omega fatty acids is favorable for human nutrition. Thus, enhancement of lipid accumulation with high proportion of omega fatty acids could help the dual use of microalgal lipids in human nutrition and biodiesel production through biorefinery. In that context, phytohormones have been identified as a promising factor to increase biomass and lipids production. However, nitrogen limitation has been discussed as a potential tool for lipid accumulation in microalgae, which results in simultaneous growth retardation. The present study aims to investigate the combined effect of N-depletion and 3-Indoleacetic acid (IAA) supplementation on lipid accumulation of the marine eustigmatophyte Nannochloropsis oceanica as one of the promising microalgae for omega fatty acids production. The study confirmed that N-starvation stimulates the lipid content of N. oceanica. IAA enhanced both growth and lipid accumulation due to enhancement of pigments biosynthesis. Therefore, combination effect of IAA and nitrogen depletion showed gradual increase in the dry weight compared to the control. Lipid analysis showed lower quantity of saturated fatty acids (SFA, 26.25%) than the sum of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Under N-depletion, SFA decreased by 12.98% compared to the control, which recorded much reduction by increasing of IAA concentration. Reduction of SFA was in favor of PUFA, mainly omega-6 and omega-3 fatty acids which increased significantly due to IAA combined with N-depletion. Thus, the present study suggests a biorefinery approach for lipids extracted from N. oceanica for dual application in nutrition followed by biodiesel production.

Microalgae as Sustainable Bio-Factories of Healthy Lipids: Evaluating Fatty Acid Content and Antioxidant Activity

“…In line with our results, previous studies reported a total absence of ALA and high abundances of EPA [ 77 , 78 , 79 , 80 , 81 , 82 ]. One study reported the presence of negligible amounts of ALA; however, the authors were evaluating the effects of the use of phytohormones and nitrogen depletion on biomass and lipid production, which might justify the presence of negligible amounts of this FA in N. oceanica [ 83 ]. Regarding these FAs, an interesting correlation was observed between the abundances of ALA and EPA.…”

Influence of different abiotic factors on lipid production by microalgae – a review

“…To date, some types of wastewater rich in organic matter, such as piggery wastewater, municipal wastewater and monosodium glutamate wastewater have been successfully utilized for the mixotrophic cultivation of microalgae (Wang et al, 2010(Wang et al, , 2012bEbrahimian et al, 2014;Aketo et al, 2020). Recent work has highlighted methods that can improve lipid production in microalgae cultivated with wastewater (Gao et al, 2019;Tan et al, 2020). Finally, Ren et al (2019) have shown that ultrasonic irradiation could be a promising process to significantly enhance the lipid production by microalgae cultivated in a non-sterile domestic wastewater.…”

Effects of Trophic Modes on the Lipid Accumulation of Parachlorella kessleri TY

“…Therefore, they are currently considered to be a potential source of biodiesel. To date, some oil-rich microalgae have already been studied, such as Chlorella vulgaris, Nannochloropsis oceanica, Scenedesmus obliquus, Selenastrum capricornutum, and so on [3][4][5][6]. A native oil-rich algal strain from Shanxi Province, Parachlorella kessleri TY, was previously screened by the authors of the current study [7].…”