Harvesting Microalgae for Food and Energy Products

Abstract

their size and physiology, and they belong to many different phylogenetic groups that are distinct from plants. [1] Microalgae are the subset of algae that are unicellular and range in size from several to a few hundred micrometers. Most microalgae diversity resides in freshwater or marine systems. Microalgae can grow in extreme environments such as deserts and polar regions, [2] and often show greater efficiency in synthesizing bioproducts compared to land plants. [3] Moreover, algae produce oxygen and sequester the greenhouse gas carbon dioxide at globally relevant scales, [4] and account for half of the oceans' net primary production. [5] They grow fast and can produce high-value biomass. [6] While microalgae are phylogenetically diverse, most biotechnology interest applies to the green algae (Chlorophyceae), diatoms (Bacillariophyceae), blue-green algae (Cyanobacteria), and Eustigmatophyceae (including Nannochloropsis), which are well-characterized species for valuable bioproducts. 1.2. Microalgae as Sustainable Biofactories Microalgae have the potential to produce large amounts of valuable products sustainably, since they do not require arable land and can be produced using seawater, wastewater, or brackish water. Reduction in environmental impacts of fuels and food products will be important for the mitigation of climate change. [7] Microalgae are also being used in powerplants as a means to capture carbon dioxide and sequester it into biomass, which may provide opportunities for large-scale production of carbon-neutral energy and products. [8] Vaccines and other pharmaceutical proteins are among the most high-value products that microalgae are used to produce, as well as effectively store and orally administer those products. [9] Other high-value products derived from microalgae include cosmetics, [10] food supplements and additives, [11] cooking oils, [12] and animal feed. [13,14] These have been developed as potentially more sustainable alternatives to synthetic or animal-derived products. Microalgae also provide feedstocks for biodiesel [15] and ethanol, [16] contributing to renewable and sustainable energy resource developments that may displace fossil fuels and food-derived fuels. Genetic and synthetic biology approaches can accelerate the development of microalgae strains capable of producing novel specialty products [17-19] or producing conventional products with improved lipid content, [20] growth rate, and production efficiency. [21,22] Unlike field-grown transgenic crops, multi ple Microalgae are promising biological factories for diverse natural products. Microalgae tout high productivity, and their biomass has value in industrial products ranging from biofuels, feedstocks, food additives, cosmetics, pharmaceuticals, and as alternatives to synthetic or animal-derived products. However, harvesting microalgae to extract bioproducts is challenging given their small size and suspension in liquid growth media. In response, technologic developments have relied upon mechanical, chemical, thermal, and b...

Biological-Based Produced Water Treatment Using Microalgae: Challenges and Efficiency

“…Microalgae can be cultivated in hot regions at 36 • C and thrive in multiple environments such as seawater, freshwater, and soil [73]. Microalgae cultivation can be conducted in open ponds or close photobioreactors (PBRs) [74,75].…”

“…Open cultivation systems are open ponds and raceway ponds, which provide the best value for the construction cost [137,138] and can be used on a large scale for microalgae cultivation [82]. However, open cultivation systems have several disadvantages: the need for large quantities of water, large land areas, high exposure to pollution, low biomass productivity, loss of algae due to wall-sticking, easy contamination (limiting the system to only a few strains of algae), and difficulty producing long-term algal cultures [73,135,136]. Further, supplying CO 2 to open cultivation systems is one of the main challenges facing microalgae cultivation because of the high cost of CO 2.…”

Bioflocculation of Euglena gracilis via direct application of fungal filaments: a rapid harvesting method

“…In addition, the flocculation rate also exhibited species dependence with each species beginning to flocculate and arriving at T max at separate times. Flocculation is thought to be governed by the interactions of surface polysaccharides which are positively charged enabling static attraction to the negatively charged microalgae, and as the cell surface composition differs by species (Feofilova 2010), flocculation ability also differs (Ummalyma et al 2017;Liber et al 2020).…”

Spirulina platensis Protein as Sustainable Ingredient for Nutritional Food Products Development

“…A sustainable and relatively novel food source of nutritional compounds are microalgae. These organisms can produce large amounts of high biological value proteins, long-chain polyunsaturated fatty acids, carotenoids, vitamins, minerals, and phenolic compounds, among others [11][12][13]. Microalgae do not compete for arable land as other food sources do and, depending on their purpose, can even be grown using non-potable water, wastewater, or even salty water.…”

“…S. platensis is rich in vitamin B 12 , as it has been reported that it can contain between 1.6 and 3.2 µg of this vitamin per gram of dried mass, which can cover between 25 and 133% of the daily intake recommendations [25]. In the last few years, microalgae biomass has been successfully applied as an additive for food products, giving innovative and healthy alternatives such as vegetarian cookies, pasta, biscuits, mayonnaise, sausages, and gelled desserts [12,26,27]. Some results have shown that the addition of S. platensis at different levels improved some physicochemical and sensorial attributes in wheat pasta such as water absorption capacity, texture, color, as well as antioxidant capacity [28].…”