Algae Materials: Applications Benefitting Health

Algae Materials: Applications Benefitting Health offers a comprehensive analysis of biosensors, algae materials for clinical applications, algae polymers, proteins and pigments, algae for food applications and packaging, blue economy, algae forming, cosmetics, and more. The book enlists the less explored areas of algal bioproducts, including how the application of genetic engineering is currently used to enhance bioproducts. Even though there are numerous reviews and scattered documents available, there are some recent fields yet to explore.

• Offers a comprehensive analysis of biosensors, algae materials for clinical applications, algae polymers, proteins and pigments, algae for food applications and packaging
• Enlists the less explored areas of algal bioproducts like how applications of genetic engineering are used to enhance bioproducts
• Includes recent findings and often excluded areas in microalgae research available in a single source

• Language: English
• Publisher: Academic Press
• Release date: Feb 22, 2023
• ISBN: 9780443188176

Book preview

Chapter 1: An introduction to algae materials

V.R. Umashree ¹ , K. Anjana ¹ , D. Vidya ¹ , B. Vinod ¹ , K. Nayana ¹ , M. Sreelakshmi ¹ , Rathinam Raja ² , and Kulanthaiyesu Arunkumar ¹       ¹ Phycoscience Laboratory, Department of Plant Science, School of Biological Sciences, Central University of Kerala, Kasaragod, Kerala, India      ² Research and Development Wing, Sree Balaji Medical College and Hospital (SBMCH), Bharath Institute of Higher Education and Research (BIHER), Chennai, Tamil Nadu, India

Abstract

Due to enormous application potential in the biopharmaceutical, nutraceutical, and renewable energy industries, algae have recently gained significant interest on a global scale. Biofuels, bioactive medicines, and food ingredients can all be produced from algae in an environmental friendly, economically feasible manner. Algae-based polymers, blends, and composites have found many applications in numerous fields of human life, i.e., from food and medical to high-tech applications. This chapter was written to shed light on the numerous biotechnological applications of algae as food, feed, fuel, and medicine as well as to give some details on various algae based materials.

Keywords

Algae; Bioethanol; Biogas; Feedstock; Fossil fuel

1. Introduction

Due to enormous application potential in the biopharmaceutical, nutraceutical, and renewable energy industries, algae have recently gained significant interest on a global scale. Biofuels, bioactive medicines, and food ingredients can all be produced from algae in an environmental friendly, economically feasible manner (Sathasivam et al., 2019). The possibility for value-added products with exceptional pharmacological and biological properties has been explored for a number of algae species (Daroch et al., 2013). Algae-based materials can exist in the form of algal polymers, blends, and composites of algal biomass or biomolecules with other polymeric materials. Because of the characteristics such as biocompatibility, biodegradability, and therapeutic activities, algae-based materials have attracted great attention from the research community (Rehman et al., 2017). Bioethanol, biogas, biohydrogen, biodiesel, etc. are the several types of algae fuels. For a variety of purposes, including the synthesis of single cell proteins, pigments, bioactive compounds, medicines, and cosmetics, algae have been investigated as food sources (Becker, 2004). Algae have been extensively used in biosensing applications in addition to biomass generation and bioremediation (Antonacci & Scognamiglio, 2020). Algae naturally create polymers that have a high potential for bioplastic synthesis. Algae provide an environmentally benign substitute for oil-based plastics, which are seriously harming the environment (Carina et al., 2021). Algae-based biomaterials are promising candidates for the replacement of conventional, nonrenewable, fossil fuel-based polymeric materials. Algae-based polymers, blends, and composites have found many applications in numerous fields of human life, i.e., from food and medical to high-tech applications (Rehman et al., 2017). This chapter was written to shed light on the numerous biotechnological applications of algae as food, feed, fuel, and medicine as well as to give some details on various algae based materials.

2. Algae materials for advanced biofuel production

The energy demands are increasing in daily life; presently, the price of fossil fuels is rising, and the burning of fossil fuels causes negative impacts on the environment. It is now important to find an alternative to fossil fuels for the world's energy supply. Biofuels find more attraction nowadays because it is a renewable energy source derived from biomass. Algae are considered a promising third-generation feedstock for biofuel production. This third-generation feedstock overcomes the drawbacks mainly found in first- and second-generation feedstocks because algal feedstocks do not compete with food supply and do not require any arable land and water resources (Kraan, 2012). Developing sophisticated algal biomass biofuel production technologies is critical for improving the cost-effectiveness of implementing a biomass-as-potential-renewable-energy approach (Alfarisi, 2020).

Biodiesel production by transesterification has also been widely investigated using heterogenous catalysts (base or acid), and heterogenous catalysts can be recycled, regenerated, and utilized again for a subsequent transesterification reaction, in contrast to homogenous catalysts (Klinthong et al., 2015). A catalyst made of an alkali or an acid is included in the homogenous catalyst. A solid acid, base, acid-base bifunctional, biomass waste-based, and nanocatalyst are all components of the heterogenous catalyst (Mandari & Devarai, 2021). It was discovered that the combination of ionic liquids with microwave irradiation had beneficial results, with only a minimal amount of ionic liquids needed to serve as a catalyst in the conversion of microalgae to biodiesel (Hasanudin et al., 2022). For in situ extractive transesterification of wet Nannochloropsis with methanol, 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim] [HSO4]) is utilized as a solvent and an acid catalyst. It indicates that [Bmim] [HSO4] catalyzed in situ transesterification is a cost-effective method of producing biodiesel (Sun et al., 2017). Other studies have reported different types of catalysts such as mordenite, metatitanic acid, PTSA, and carbonized vegetable oil asphalt (Tabatabaei et al., 2015). According to Madison, ionic liquids with Brønsted acidity or basicity pose no environmental concern and produce a high biodiesel yield quickly and under mild reaction circumstances (Ong et al., 2021).

3. Valorizing algae biomass as materials for bioproducts and commercial application

Algal biomass is a viable feedstock for producing a variety of value-added compounds and products, such as food, feed, and fuel, in a sustainable manner. Algal extracts are excellent sources of biotechnologically viable chemicals that have antimicrobial, antioxidant, antiinflammatory, anticancer, and other medicinal and therapeutic activities. PUFA, essential oils, vitamins, antioxidants, carotenoids, and other metabolites derived from algal biomass have been reported to have exceptional nutritional and medicinal benefits (Sathasivam et al., 2019). According to studies, Chlorococcum infusionum, Chlamydomonas reinhardtii UTEX 90, Chlorella vulgaris, and C. reinhardtii are all viable options for large-scale bioethanol production (Daroch et al., 2013). Spirulina has achieved widespread appeal as a food supplement due to its high protein content and outstanding nutritious value (Sathasivam et al., 2019). The carotenoid produced by Dunaliella sp. and Haematococcus sp., as well as the lutein produced by Muriellopsis sp., is vital for fish larvae growth (Sathasivam et al., 2019).

The majority of carotenoids have medicinal properties, such as antiinflammatory and anticancer properties, which are mostly due to their powerful antioxidant impact, which protects organisms from oxidative stress. Essential fatty acids are produced by microalgal species such as Crypthecodinium and Schizochytrium. Schizochytrium strains that produce DHA and EPA are currently employed as an adult dietary supplement in cheeses, yoghurts, and breakfast cereals (Sathasivam et al., 2019). Algal extracts are utilized in various products, including antiaging creams, sunscreens, moisturizers, and emulsifiers (Aslam et al., 2021). Pimental et al. looked at existing commercial cosmetics derived from algae, including carrageenan, Gelcarin, alginate, and others, and found that these compounds are recognized as useful skin care products (Pimentel et al., 2018).

In general, algae include a variety of components that are thought to be extremely important and have a wide range of applications. Carbohydrates are utilized in the fermentation process; lipids are used in the creation of biodiesel, protein, and fatty acids; and pigments are employed in nutraceutical and pharmaceutical applications (Sudhakar et al., 2019). Because of their potential to lessen reliance on petroleum-based fuels and chemicals, interest in algae-based biofuels and chemicals has grown in recent years. Algae are widely regarded as the most ideal and long-term feedstock for producing green energy, as the entire process is carbon-neutral and may also be used for environmental cleanup (Trivedi et al., 2015). Algae have a lot of promise for usage as a biorefinery raw material because it can make a variety of products. As a result, rather than the traditional single product line strategy, a matrix method with many alternatives is preferable for successful algal biorefinery operation.

4. Algae materials for food and food packaging

Due to the modern lifestyle, people in most industrialized countries consume high-calorie foods, which contribute to obesity, diabetes, and heart problems. A healthy diet should include vitamins, minerals, polyunsaturated fatty acids (PUFAs), and other nutrients. Microalgae are a fantastic but understudied natural source of nutrients for a balanced diet. Several microalgae species have been found as being high in carbohydrates, proteins, lipids, and other nutritionally important components. Vitamins A, B1, B2, C, and E, as well as nicotinate, biotin, folic acid, pantothenic acid, niacin, iodine, potassium, iron, magnesium, and calcium, are rich in microalgae (Becker, 2004). Nostoc sp. was first taken as a food by the Chinese over 2000 years ago, and later, varieties of microalgae (Chlorella sp. and Spirulina sp.) were consumed as nutritious foods in Japan, Taiwan, and Mexico (Sathasivam et al., 2019). Most marketed microalgae products are now sold as healthy foods in the form of tablets, capsules, and liquids, and their products are mixed with snacks, sweets, beverages, and breakfast cereals. Some of the microalgae species extensively used as a human food source are Aphanizomenon flos-aquae, Chlorella sp., Dunaliella salina, Dunaliella tertiolecta, and Spirulina platensis (Sathasivam et al., 2019). Algae continue to be a novel food source (Mellor et al., 2022). However, understanding of the benefits of eating algae is needed to aware consumers to eat algal-based foods.

The modern food sector relies heavily on packaging. It is required for food preservation and ensures the food's safety and integrity. Packaging is an important aspect of our supply chain because of these benefits, but it also has drawbacks, such as contaminant residue migration, cost and energy efficiency, and sustainability. Glass, paper, various metals, and plastic are all regularly used materials for food packaging; nevertheless, plastics, after paper, are the most commonly utilized. Petroleum is used to make the majority of the plastics we use. But, even worse, it is tossed in the trash to be incinerated once it has been used. When it is burned, carbon dioxide is released into the atmosphere, which contributes to the greenhouse effect. Others simply discard plastic bottles and packaging into the environment, polluting ecosystem and affecting animal and human lives for ages because plastics take decades to disintegrate. Polymers that are biodegradable and biobased have been produced and are now available on the market to lessen these effects and establish a more sustainable approach to food packaging. Bioplastics manufactured from algae are nowadays proved to be a good food packaging material. In practice, it can be extracting a number of compounds from the biomass and converts them into plastic.

Seaweeds, which are high in polysaccharides, are thought to be a possible active agent or raw material. When mixed with any biodegradable polymer, they are better alternatives to traditional materials since they improve the product's sustainability, functionality, and sensory properties (Carina et al., 2021). Alginates are biopolymers made up of natural hydrophilic polysaccharide biopolymers derived primarily from marine brown algae. Alginates were first employed as a coating for perishable fresh fruits and vegetables to reduce respiration rate, but they can now be used to extend the shelf life of a wide range of foods (Kontominas, 2020). Alginates can work together to create a multifunction food packaging system, when employed as part of the green packaging technologies. Cladophora was chosen as a cellulose source because its cell walls contain a significant quantity of crystalline cellulose. When compared with other sources of cellulose, Cladophora algal cellulose has good mechanical characteristics. They have the potential to be developed as environmentally friendly, long-lasting packaging materials (Steven et al., 2020).

5. Superfood (algae)—in future

Microalgae have a wide range of potential for improving the nutritional content of traditional food preparations and acting as probiotic agents that benefit human and animal health (Becker, 2004). Microalgae are now commonly sold as a healthy food or supplement in the form of tablets, capsules, and liquids. Algae are also used in pasta, snacks, candy bars, and drinks, among other things, as a nutritional supplement or a natural food colorant. Nannochloropsis, Tetraselmis, Isochrysis, Thalassiosira, and Chaetoceros are microalgae that may synthesize long-chain fatty acids such as DHA and EPA, which are helpful as healthy food supplements (Chew et al., 2017; Priyadarshani & Rath, 2012). Carotenoids, chlorophylls, and phycobiliproteins are three primary groups of natural pigments in microalgae. These pigments have been used in food as vitamin precursors. In microalgae, phycobiliproteins are the most important photosynthetic accessory pigments. Natural colors in the food sector are one of the most common uses of phycobiliproteins. It possesses antioxidant, antiviral, anticancer, antiallergic, antiinflammatory, and neuroprotective characteristics, making it a promising substance for healthcare applications (Chew et al., 2017). Health-promoting and disease-suppressing metabolites abound in microalgae. Microalgae include a wide range of carotenoids, fatty acids, amino acids, antioxidants, and other secondary metabolites that boost the nutritional value of human and animal diets. Vitamins abound in microalgae. Microalgae such as Dunaliella tertiolecta and Tetraselmis suecica cultivated under nitrogen-deficient circumstances produce more vitamin E. Vitamin E is used in various ways. Cancer, heart disease, eye illness, Alzheimer's disease, Parkinson’s disease, and other medical disorders are treated with it (Sathasivam et al., 2019).

Asiatic countries have employed green microalgae for hundreds of years as nutritional supplements or food sources. They are now consumed all around the world for their nutritional properties. The green algae C. vulgaris, Haematococcus pluvialis, Dunaliella salina, and the Cyanobacteria Spirulina maxima are among the most biotechnologically important microalgae (Priyadarshani & Rath, 2012). They are widely sold and used, primarily as nutritional supplements for humans. Millions of people eat seaweed worldwide, from Japan to Chile, South Africa to Belize, and even England. Seaweed has numerous advantages (Mellor et al., 2022). It is exceptionally nutritious since it contains numerous beneficial minerals and vitamins for the human body. Seaweed is also simple to grow, and because it is grown in water, it does not take up valuable land area. It develops swiftly and may thrive in dirty waters and in environments where typical food crops would perish. In the quest for more sustainable food systems for the future, microalgae are one of the most promising sustainable sources of food components.

6. Advanced instruments in algae materials: applications and characterization

Concerns about the environment and the finite supply of fossil fuels have driven research into biofuels and biomaterials. Biomaterials not only eliminate the problems associated with using traditional fossil fuel-based polymeric materials but also having characteristics that make them suited for a wider range of applications. Algae-based polymers, composites, and mixes are a significant class of biomaterials with applications in various sectors. Algal polymers, blends, and composites of algal biomass or biomolecules with other polymeric materials are all examples of algae-based materials (Kontominas, 2020).

The desire for a better alternative to present plastic products has given rise to algae-based bioplastic manufacture, which appears to be both biodegradable and cost-effective. A wide range of algal biopolymers attract a lot of attention as a way to combat the growing problem of plastic waste and environmental contamination. Polysaccharides derived from algae, including agar, alginate, and carrageenan, have been identified as interesting possibilities for delivery system design. The physicochemical characteristics of algal polysaccharides vary greatly. Furthermore, they have outstanding gelling qualities. These polysaccharides' physicochemical features allow them to be used in various targeted and controlled drug delivery methods, including particles, capsules, and gels (Rahmati et al., 2019).

For water quality analysis, a low-cost algae-based biosensor has been developed (Prudkin-Silva et al., 2021). Algal fuel cells (AFCs) are bioelectric devices that convert light and metabolic energy into electrical energy using photosynthetic organisms (Kannan & Donnellan, 2021). The potential of a fully biotic algal fuel cell is still being researched, which has led to a rethinking of the potential application of plant-based bioelectricity. Algae have been proved to be a viable fuel source for microbial fuel cells, either as an internally generated carbon source (due to their growth in an illuminated anodic compartment) or as an external carbon source (Walter et al., 2015). Because algae are good water quality indicators, studying them is an important part of water monitoring.

The measurement of chlorophyll-a, the primary photosynthetic pigment in algae, is one of several ways to estimate their quantity. Algal species have a variety of pigments, the detection of which can be used to determine algal composition based on the distinct light spectrum employed in the procedure. Fluorescence is a phenomenon in which a sample is activated by electromagnetic radiation at one wavelength and responds by emitting light at another slightly higher wavelength, which can be used to detect chlorophyll (Diána et al., n.d.). Today, equipment that uses fluorescence to estimate chlorophyll concentration and algal composition is accessible. In general, algal materials have a wide range of applications in research and industrial sectors.

7. Advancement in algae cultivation techniques

Autotrophs such as algae produce a variety of interesting compounds (Terrado et al., 2017). In Asia, algae have traditionally been viewed as a vital nutritional source, and many have eaten them in their diet, eventually gaining prominence in Europe, South America, North America, and Australia (Apurav et al., 2019). According to archaeological evidence found in Chile, this event took place 14,000 years ago (Dillehay et al., 2013). Nutraceuticals, pharmaceuticals, and cosmetics companies use algae for their bioactive compounds. Algae cultivation became more common as demand for raw materials increased (Bruna et al., 2015). More than 370 years have passed since algae have been cultivated for human consumption (Liang et al., 2015).

It is really challenging to cultivate algae on a commercial scale. Science and social acceptance are two challenges. They include the development of a cost-effective and eco-friendly farming system, which is adapted to optimum temperatures, healthy, and disease-resistant. In addition to cultivation onshore, algae were grown offshore as well. In the case of offshore cultivation, the method of cultivation differs from that of onshore cultivation. It is also an economical method to cultivate offshore. There has been a growing interest in offshore cultivation as a cost-effective method as well. Due to the lack of land use, regulating temperature, sunlight intensity, and nutrients is not required (Bak & Infante, 2020). During offline cultivation, environmental services are also provided since nitrogen and phosphorus are removed from algae, improving water quality for aquatic organisms. In addition, this nitrogen is also used to produce biofuels through combined algal processing. Economic and environmental sustainability of algal biorefineries are influenced by algal cultivation locations. In the pharmaceuticals, cosmetics, nutraceuticals, and biofuel industries, algal metabolites are important sources of lipids, polyunsaturated fatty acids, pigments, proteins, carbohydrates, vitamins, and antioxidants (Udayan et al., 2021).

Nutrient bioharvesting can be achieved with seaweed aquaculture. A suitable species for seaweed aquaculture should be selected depending on its purpose and efficiency. The limited supply of fossil fuels has created a high demand for clean, affordable, and sustainable energy sources. To realize the growing demand for energy and to achieve sustainable development, the algae industrial revolution has proved to be one of the most significant steps. Algal cultivation is currently used mostly to produce biodiesel from algal lipids. There are several benefits of using biodiesel as an alternative diesel fuel; it is biodegradable and nontoxic as well as highly lubricating (Das et al., 2020). A fast growth rate and high biomass productivity make algae an ideal feedstock for biofuel production. By cultivating algae in conjunction with wastewater and flue gas treatment, algae can simultaneously function as carbon sinks and purifiers. To determine whether it is worthwhile to scale up and commercialize algal cultivation for biofuel production, it becomes especially important to understand the overall supply chains for algal biofuels production (Lam & Lee, 2013).

8. Expanding algal polymers, proteins, and pigments as materials for industrial applications

There are a number of pigments present in algae such as chlorophyll, carotenoids, and phycobiliproteins, which exhibit colors ranging from green, yellow, brown, and red. Increasing awareness in society of the harmful effects of synthetic dyes as well as society's shift toward natural products has made algae a desirable resource. Spirulina and Dunaliella capsules are now commonly prescribed healthy foods to enhance human vitality and longevity. Because of their commercial value as natural colorants, algal pigments have great potential for use in nutraceutical, cosmetics, and pharmaceutical products (Chakdar & Pabbi, 2017).

Algae-based bioplastic production is a promising alternative to existing plastic products thanks to its excellent biodegradability and cost-effectiveness. As the surge of plastic waste and environmental pollution becomes more severe, algal biopolymers draw great attention. Polymers extracted from cyanobacteria include polyhydroxyalkanoates and poly-(hydroxybutyrate). Natural polymers include algal polysaccharides (alginate, laminarin, fucoidan, carrageenan, agar, ulvan) (Dove et al., 2020; Lee & Mooney, 2013; Santos & Grenha, 2015). A variety of microbes produce polyhydroxyalkanoates as esters, which constitute the structural foundation for a wide range of biomolecules (Hempel et al., 2011). Two types of cellulose acetate sheets were created by embedding two algal seaweeds (Ulva fasciata and Sargassum dentifolium) into cellulose acetate (CA) polymer; Ulva sheets (CA-U), and Sargassum sheets (CA-S) (Moghazy et al., 2020).

In the past hundreds of years, dried microalgae have been used as a food source. Recent efforts have focused on developing microalgae for use as food sources on a commercial scale because they accumulate large amounts of protein and oil. Biofuels seem to account for most of the oil production. FDA has designated algal protein as GRAS in the United States. Currently, its intensely green color limits its food applications (Zeece, n.d.). The food industry uses a very limited amount of algae proteins or purified protein fractions. As a blue chromoprotein in foods, phycobiliproteins serve as a family chemical used for food coloring in Japan. Spirulina sp. contains the pigment phycocyanin. The product is sold as Lina Blue-A. In red algae, pigments of the same type, but in purple or red colors, phlorocyanins and phycoerythrins, are also present. These chromoproteins possess unique spectral properties, which make them ideal for use as food-coloring agents. In addition to possessing unique spectral properties, chromoproteins could be used to color foods (Sekar, 2008, pp. 113–136).

Commercially valuable pigments extracted from micro- and macroalgae available in the markets are beta carotene, astaxanthin, fucoxanthin, phycocyanin, phycoerythrin, lutein, and chlorophyll. To develop a sustainable and commercially viable microalgal bioindustry, it is essential to effectively recover these pigments. The increasing toxicity of textile effluents generated by synthetic dyes has prompted the search for alternatives without toxicity. These pigments have been found to possess antimicrobial and antioxidant properties, so dyeing fabric with algae can also be used as a food colorant. As meditextiles can be made from these pigments due to their antimicrobial properties, they have excellent potential for use in hospitals (Jamee & Siddique, 2019).

9. Algae for blue economy and blue carbon materials and their application in various fields

The term blue has recently been reframed in relation to human use of the ocean for economic purposes. In addition to being an alternative development paradigm, the blue economy promotes economic, social, and environmental benefits (Isurupremarathna, 2021). Blue economies have been defined in different ways. Here, they are understood as parts of the economic system and policies associated with sustainable use of oceanic resources. Oceanic sustainability includes sustainable fisheries, ecosystem health, and pollution, which is an important challenge of the blue economy. Taking into account this international policy context, the blue economy encompasses activities that provide access to the ocean’s resources, explore, develop, and utilize the ocean’s space, as well as conserve the ocean’s ecosystems (Bari, 2017). A blue economy’s other pillars, including improving human well-being and social equity as well as reducing environmental risks and ecological scarcities, are also well understood by science and technology (Hassanali, 2020).

Blue carbon is a part of the blue economy. Oceanic plants, such as seagrasses, mangroves, and tidal marshes, capture and store carbon in the form of blue carbon. These plants are highly productive and store high levels of carbon. Mangrove and saltmarsh carbon stocks, and not seagrass, may influence management actions and ecological processes depending on their position within the estuary (Cacho et al., 2021). Researchers conducted a study of salt marsh blue carbon stocks in Sri Lanka, and their findings expanded our understanding of global and regional saltmarsh carbon stocks (Kauffman et al., 2018).

10. Algae and farming applications—present and future scenario

As the demand for fossil fuels increases, the current reserves are insufficient to meet it and are very likely to be exhausted very soon. The quest for renewable energy sources has been sparked by global warming, pollution, and inflated oil prices. A viable and promising renewable resource for biofuels production is macroalgae (green, brown, and red marine seaweed). Macroalgae are believed to provide diverse bioproducts including biofuels and have been the subject of numerous research studies. Microalgae are an enviable source of biofuels because of their carbohydrate and lipid composition, along with their lack of lignin. In Europe, there are currently 447 production units for algae and Spirulina species. European countries have identified a variety of species, production methods, and commercial applications. The majority of macroalgae production units in Europe are harvested from wild stocks (68%). Spirulina sp. are primarily produced in open ponds (83%), while microalgae are mostly grown in photobioreactors (71%) (Araújo et al., 2021).

To boost the growth of the sector in Europe, the industry needs to ramp up its production volume and to progress in technological and market development. Currently in the precommercial phase, algae are one of the hottest emerging industries in the EU Blue Bioeconomy. In addition, using current methods and technologies to redefining primary energy usage, such as cooking and heating, is the key to the development of the future energy sector. In addition to stimulating global economic growth, algae-based energy has also helped advance the human civilization (Araújo et al., 2021).

It has been 25 years since the global demand for seaweed, and its products expanded exponentially. A great deal of potential exists for seaweed production on the continent of Africa as well as on its offshore islands. African seaweed production and consumption are lower than that of China and the rest of Asia. As far as red eucheumatoid seaweeds are concerned, Africa ranks third after Asia and Latin America. In the tropical, carrageenan-producing eucheumatoids of the rainforests to the temperate, carrageenan-producing kelp species of the southwest, seaweeds can be grown along the continent’s diverse ecosystems. It has improved the livelihoods of coastal people in Africa through seaweed aquaculture production led mostly by women. A major constraint to the development of this industry includes disease outbreaks and pest outbreaks due to climate change. As the continent grows and expands its production and utilization of seaweeds, it can compete with China and Southeast Asia for global leadership (Msuya et al., 2022).

11. Algae materials for quorum sensing applications

Several physiological functions of microorganisms are controlled by quorum sensing (QS), including biofilm formation, bioluminescence, and antibiotic production (Rutherford & Bassler, 2012, pp. 1–25). It may be possible to alter the production of algicidal metabolites by the marine algicidal bacterium, Ponticoccus sp.PD-2, by inhibiting the QS system. In the process of disintegrating red tides, the QS-regulated algicidal system may be involved. To control red tides, QS might be a useful tool (Chi et al., 2017). Algae are ubiquitous in the marine environment, and the ways in which they interact with bacteria are of particular interest in marine ecology field. The interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape microbial diversity Although algal–bacterial interactions are well known and studied, information regarding the chemical–ecological role of this relationship remains limited, particularly with respect to QS, which is a system of stimuli and response correlated to population density (Lami, 2019). In the microbial biosphere, QS is pivotal in driving community structure and regulating behavioral ecology, including biofilm formation, virulence, antibiotic resistance, swarming motility, and secondary metabolite production. Many marine habitats, such as the phycosphere, harbor diverse populations of microorganisms and various signal languages (such as QS-based autoinducers) (Zhou et al., 2016).

QS-mediated interactions widely influence algal–bacterial symbiotic relationships, which in turn determine community organization, population structure, and ecosystem functioning. Understanding info chemicals-mediated ecological processes may shed light on the symbiotic interactions between algae host and associated microbes. In this chapter, we summarize current achievements about how QS modulates microbial behavior, affects symbiotic relationships, and regulates phytoplankton chemical ecological processes (Zhou et al., 2017) and role of microalgae-associated microorganisms with the QS system in algae–bacteria interactions and community succession of harmful algal blooms microalgae (Zhang et al., 2022). Algal biomass productivity increased by 2.25 times by QS molecules. QS molecule enhanced lipid content of Chlorella sorokiniana by 1.28. Bacterial QS molecules also improved the photosynthetic efficiency of Chlorella sorokiniana. Settling efficiency also increased by 2.5 times by these molecules. 74% higher CE for microbial fuel cell with QS induced lipid-extracted algae as anodic substrate (Das et al., 2019).

12. Algae-derived hard steel and building materials and application

Carbon fiber composite technology is an engineering tool for lowering the weight of vehicles and reducing their fuel consumption (Mathijsen, 2020). It requires the use of carbon fibers that can do exactly the same, or close enough to the automotive steel design manuals and the high-strength steel application design guidelines (Koumoulos et al., 2019). The production of carbon fiber requires fossil materials and a lot of energy. As a low-cost substitute, researchers identified that algae can be used for the production of carbon fibers. Then it would be a perfect green alternative to steel and aluminum (Mathijsen, 2020). Carbon fibers are, by far, the most widely used fiber in high-performance applications because of their lighter, stronger, and more durable solutions (Koumoulos et al., 2019). Researchers from the Technical University of Munich (TUM) developed a way to make carbon fibers, from halophilic algae, to remove CO2 from the atmosphere and subsequently to make carbon fiber (Francis, 2019).

Algae oil consists of two basic components: a backbone of glycerin with fatty acids esterified onto the hydroxyl groups (Mathijsen, 2020). Algae convert atmospheric CO2 into biomass and, subsequently, algae oil. The algae oil is produced by a nutrient depletion phase where nitrogen is limited in the culture medium, which triggers the accumulation of lipids. Algae oil is then hydrolyzed to get free fatty acids from the glycerol backbone (Francis, 2019). To convert glycerin into carbon fiber, the first step includes use of ammonia to turn the glycerin into acrylonitrile and then a polymerization reaction that produces polyacrylonitrile (PAN) (Mathijsen, 2020). PAN is the precursor for 90% of carbon fiber production (Francis, 2019). Polyacrylonitrile is turned into carbon fiber by heating up the fibers in a furnace to 2000 or 3000°C, depending on the desired properties (Mathijsen, 2020).

Applications include new crash-absorbing structures in automotive engineering, more efficient gas diffusion structures for fuel cells, adsorptive fibers for hydrogen high-pressure tanks, next-generation energy storage systems, cell-compatible fibers to replace nerve tracts in paraplegia, prosthetics with tailored properties to avoid stress shielding, reinforcement structures for carbon concrete, for wind turbine rotor blades, and many more (Koumoulos et al., 2019). Uwe Arnold, a world-renowned specialist for technology assessment and technoeconomical analyses, and Kolja Kuse came up with an innovative way of replacing cement by joining carbon fiber to natural stone. That is very relevant because cement accounts for up to 7% of all CO2 emissions (Mathijsen, 2020).

13. Algae-derived materials for applications in automobile industries

The major application of algae derived materials on automobile industries relies on the production of biofuel. When compared with standard fuel Jet A, biofuels is better regarding the technical parameters such as freeze point, density, and viscosity of fuel. Moreover, biofuels are more efficient than petroleum fuels due to their high energy than standard fuels. Also, biofuels are environmentally friendly because during combustion of biodiesel the engine emits lesser amount of CO2 and no sulfur oxides (Zabochnicka-Swiatek, 2010). Another interesting application is that algae-derived material can be used for designing biocatalytic converter that can eliminate the pollutants released by automobile engine exhaust (Ganji & Yenugula, 2017). It has been found that the addition of algal fillers to vinyl ester composites can improve its tensile strength and can be thus benefitted in the automobile industry (Bharathkumar et al., 2018). Microalgae C. vulgaris can be used as a potential candidate for the bioremediation of lead pollution caused by automobile industry (Chaudhuri & Sole Author-Chaudhuri, 2022).

14. Algae-derived biosensor materials and their applications

Biosensors are analytical devices that convert a biological response into an electrical signal. Biosensors have been used in different industries, including the food industry, the medical profession, and the marine sector, and they provide more stability and sensitivity than traditional approaches (Mehrotra, 2016). Algae have been extensively used in biosensing applications, in addition to biomass generation and bioremediation (Antonacci & Scognamiglio, 2020). Algae-based biosensors have shown promise in detecting analytes of agroenvironmental and security concerns in a sensitive and long-term. The availability of numerous algal bioreceptors, including whole cells and photosynthetic subcomponents, is one of its advantages. This can be incorporate into dual-transduction miniature devices, to monitor the environment continuously (Antonacci & Scognamiglio, 2020).

The key benefit of utilizing algae is that they are more adaptable to different settings than other bioreceptors since they are minor subjects to physicochemical changes. Researchers look into the prospects of using microalgae as sensor elements for biological pollution sensors. When microalgae-based biosensors are used for ecological monitoring of the aquatic environment, the condition of microalgal cells, as well as their uniformity and concentration, which is affected by the temperature, illumination, and chemical composition of the water, is found to influence the functioning of biological sensors (Voznesenskiy et al., 2016). In previous research, a system for water quality monitoring employing living green algae (Chlorella kessleri) and the intelligent mobile lab (IMOLA) was established (Umar et al., 2015).

Environmental applications of algal-based biosensors mainly include monitoring current issues such as water and air pollution, overfertilization, pesticide monitoring, etc. Even though many efficient biosensors for toxicity sensing using different aquatic organisms are used, the biosensors based on microalgae were identified as the most sensitive to waterborne chemicals compared with others. One of the main advantages of employing algae for environmental monitoring is the ability to develop enormous populations quickly. Algae respond to a wide range of pollutants quickly and consistently, providing potentially important early warning signs of deteriorating conditions.

In one study, Scenedesmus acutus and Pseudokirchneriella subcapitata were trapped in alginate beads and used as bioindicators (Prudkin-Silva et al., 2021). The device that was created was successfully tested. Without any scientific expertise, children, adults, and the elderly were able to construct the sensor and analyze the results. Despite challenges such as low stability and selectivity, algae-based biosensing is a viable option with some recent applications. The potential of algae-based sensors will be realized through the strategic use of cutting-edge technologies such as materials science, nanotechnology, etc.

15. Algae materials for bionanopesticides: nanoparticles and composites

The explosive increase in the global population leads to an increased demand for producing high-quality food. Limited agricultural land availability and loss of yield due to pest attacks were the major challenges for agricultural production. In this scenario, it is necessary to formulate a high efficient, eco-friendly pesticide with minimum investment. The application of nanotechnology for sustainable agricultural development by using bionanopesticides, bionanofertilizer, and bionanoherbicides will help increase agricultural productivity (Lade et al., 2019). For the safe and cost-effective production and use of pesticides, they should be effective against a wide variety of pests, nontoxic to farmers, and easy to prepare, must not get accumulated in the food chain, must not affect the quality of food, and should be safer to the