The effect of physicochemical conditions and nutrient sources on maximizing the growth and lipid productivity of green microalgae

Abstract

SUMMARY Biodiesel is a renewable fuel produced mostly from edible and non‐edible vegetables, by transesterification of neutral lipids (triacylglycerols). However, vegetable oil‐based biodiesel production competes with food crops for arable land, increasing food prices and leading to biodiversity loss. The production of biodiesel from oleaginous microorganisms – particularly microalgae – has attracted attention due to the higher lipid productivity of these organisms, when compared with vegetables. Several environmental factors – including light, temperature, pH and the presence of nutrients (particularly nitrogen, phosphorus and iron) – influence directly the ability of microalgae to produce and store triacylglycerols and other lipids, and also modulate microalgal growth. Although some environmental factors affect several species in a similar manner, differential responses between species are frequent, highlighting the importance of identifying optimal cultivation conditions for each species, to balance growth and lipid productivity for biodiesel production. Here, we reviewed the particular influence of the physicochemical and nutritional factors on the growth and lipid productivity of different green oleaginous microalgae species.

Effect of nitrate feeding strategies on lipid and biomass productivities in fed‐batch cultures of Nannochloropsis gaditana

“…But the current cultivation approaches cannot enhance the lipid contents of cells without decreasing the growth rate. Lipids are secondary metabolites directly related to the biological potential of the species, and their synthesis is triggered as a response to adverse growth conditions 7‐9 . The selection of strains based on the robustness, metabolic versatility, and flexibility for adaption to environmental variations is most important for efficient biomass generation.…”

“…Lipids are secondary metabolites directly related to the biological potential of the species, and their synthesis is triggered as a response to adverse growth conditions. [7][8][9] The selection of strains based on the robustness, metabolic versatility, and flexibility for adaption to environmental variations is most important for efficient biomass generation. Microalgae are genetically diverse groups of organisms that possess a wide range of physiological and biochemical characteristics.…”

“…The limitation of nitrates in media and the availability of an excessive flow of cystol carbon force the metabolic change from carbohydrate synthesis to lipid production through stochastic gene regulation. 8,9 The decrease of nitrogen in stroma limits the production of nitrogen-rich components like enzymes, protein, and chlorophyll components, which result in the cessation of the growth. 19 The promotion of nutrient-induced stress exerts a negative correlation between lipid and biomass production.…”

Exploiting microalgal competition ability to acquire nitrogen and light

“…Interspecific competition for light was speculated to influence light availability and nutrient supply ratio and subsequently the photosynthetic rate of algal cells in close vicinity (EPC6Programme 2015). Nitrogen restrictions decrease cellular chlorophyll levels because nitrogen is a critical element in the chlorophyll (Da Silva Ferreira & Sant'anna 2017). Ammonia is a favorite nutrient for Scenedesmus which tends to form coenobia to increase the cell size and surface capable of increasing volumetric productivities (Bohutskyi et al .…”

Manipulation of Chlorella vulgaris polyunsaturated ω‐3 fatty acid profile by supplementation with vegetable amino acids and fatty acids

“…Nutrient starvation or diet limitation of algae is thought to be a feasible approach to induce lipid and fatty acid production (da Silva Ferreira and Sant'Anna 2017). Nutritional disorders, such as nitrogen and iron deficiency, and salt stress, as well as physical environments (temperature and light intensity) and physiological factors (growth phase, physiological status), affect the lipid contents and fatty acid compositions in microalgae (Aratboni et al .…”