Improving ‘Lipid Productivity’ in Microalgae by Bilateral Enhancement of Biomass and Lipid Contents: A Review

Abstract

Microalgae have received widespread interest owing to their potential in biofuel production. However, economical microalgal biomass production is conditioned by enhancing the lipid accumulation without decreasing growth rate or by increasing both simultaneously. While extensive investigation has been performed on promoting the economic feasibility of microalgal-based biofuel production that aims to increase the productivity of microalgae species, only a handful of them deal with increasing lipid productivity (based on lipid contents and growth rate) in the feedstock production process. The purpose of this review is to provide an overview of the recent advances and novel approaches in promoting lipid productivity (depends on biomass and lipid contents) in feedstock production from strain selection to after-harvesting stages. The current study comprises two parts. In the first part, bilateral improving biomass/lipid production will be investigated in upstream measures, including strain selection, genetic engineering, and cultivation stages. In the second part, the enhancement of lipid productivity will be discussed in the downstream measure included in the harvesting and after-harvesting stages. An integrated approach involving the strategies for increasing lipid productivity in up- and down-stream measures can be a breakthrough approach that would promote the commercialization of market-driven microalgae-derived biofuel production.

Chemical composition of selected marine microalgae, with emphasis on lipid and carbohydrate production for potential use as feed resources

“…The total lipid content of the algae species investigated varied between 10 and 34% of dry matter, and all species obtained increased lipid content with reduced relative growth rates due to nutrient limitation. This is in agreement with earlier reports (Reitan et al 1994;Brown et al 1997;Shokravi et al 2020). The highest lipid content was found in N. oculata grown at 4% relative growth rate, followed by C. muelleri and T. lutea, both also at 4% relative growth rate.…”

Strategies to Produce Cost-Effective Third-Generation Biofuel From Microalgae

“…The use of optimum temperature and pH, supply of adequate CO 2 , exposure to nanoparticles, and induction of metal, nutrient, oxidative, and salinity stress can also affect biomass and obtain maximum lipid production, but the effect of each factor can vary from strain to strain (Sibi et al, 2016;Alishah Aratboni et al, 2019). Attributed to advancements in synthetic biology, a novel way of genetic modification of microalgae to improve lipid productivity has been garnering significant attention recently (Alishah Aratboni et al, 2019;Shokravi et al, 2020).…”

Production of microalgae with high lipid content and their potential as sources of nutraceuticals

“… 0.607 Xia et al ( 2013 ) Nannochloropsis oculata 0.324 Shokravi et al ( 2020 ) Dunaliella salina 0.565 Abomohra et al ( 2020 ) Salinity stress + nitrogen starvation Tetraselmis sp . 0.285 Park et al ( 2018 ) Chlorella vulgaris 0.8 Mirizadeh et al ( 2020 ) Phytohormones Chlorella sorokiniana 0.502 Guldhe et al ( 2019 ) Phytohormones + nitrogen starvation Chlorella sorokiniana 0.69 Babu et al ( 2017 ) Combination of NaCl/CaCl 2 Chamydomonas reinhardtii 0.109 Hang et al ( 2020 ) Salinity + nitrogenstarvation + wastewater Chlorella vulgaris 0.080 Mirizadeh et al ( 2020 ) Muncipalwastewater + seawater Phaeodactylum tricornutum 0.054 Wang et al ( 2019 ) Two stage photoautotrophic and mixotrophic cultivation Chlorella vulgaris 0.108 Shokravi et al ( 2020 ) Farm wastewater Chlorella sorokiniana 0.083 Shokravi et al ( …”