Advancement and role of abiotic stresses in microalgae biorefinery with a focus on lipid production

Microalgae have been determined as an alternative and potential feedstock for carbon–neutral biofuel production over other sources due to their ability to grow at higher rates, production of high-energy molecules, fixation of CO2 with high efficiency and ability to treat wastewater. Currently, research is focused on inexpensive and eco-friendly strategies to induce lipid synthesis in microalgae for biodiesel production. The abiotic stresses have appeared as a promising strategy. The main objective of this study is to delineate the effects of various abiotic stresses on microalgal biofuel production. Abiotic growth factors such as nutrients, temperature, pH, salinity, light and chemical effects have been shown to facilitate the cultivation of microalgae with high lipid production. The present paper comprehensively reviews the recent advances in microalgae cultivation and strategies to induce lipid production via the manipulation of abiotic growth factors. The utilization and bioprocessing of algal biomass towards biodiesel production are also briefly discussed. The study also reviews the role of abiotic stresses in biosynthetic gene response of lipid synthesis and metabolisms. Optimization and abiotic growth factors manipulations in microalgae cultivation are inexpensive and efficient strategies for high lipid and biomass accumulation in large-scale facilities. For these reasons, future research efforts can be focused on the combination of these manipulations to improve the biomass and lipid productivity in microalgae. It is concluded that the commercialization of algae-based biofuels via cost-effective and multi-product generation routes in biorefinery of biodiesel production is still valid in the wave of global decarbonization movement.