Disruption of thermo-tolerant Desmodesmus sp. F51 in high pressure homogenization as a prelude to carotenoids extraction

Bioprocess to produce biostimulants/biofertilizers based on microalgae grown using piggery wastewater as nutrient source

In the present work, two downstream processes - high-pressure homogenization at 100 (HPH-100) and 1200 bar (HPH-1200), and enzymatic hydrolysis (EH) - were tested to produce biostimulant extracts from Tetradesmus obliquus grown in piggery wastewater at two concentrations (12.8 and 88.3 g/L). Extracts before and after centrifugation (C) were evaluated in four bioassays using garden cress (germination), mung bean (auxin-like activity), and cucumber (auxin- and cytokinin-like activity) relative to distilled water. The initial microalgal culture, without any treatment, had the best germination results (162 % at 0.2 g/L) and the only one that showed cytokinin-like activity (141 % at 0.5 g/L). In both auxin-like bioassays, the HPH-1200 + C and EH + C originated high values (186 and 155 % for cucumber, 290 and 285 % for mung bean, respectively). For mung bean, the HPH-1200 achieved the highest auxin-like effect (378 %). Finally, the extracted biomass contained essential nutrients for biofertilization, complementing the biostimulant extracts for sustainable agriculture application.

Simultaneous Lipid and Carotenoid Production via Rhodotorula paludigena CM33 Using Crude Glycerol as the Main Substrate: Pilot-Scale Experiments

Rhodotorula paludigena CM33 is an oleaginous yeast that has been demonstrated to accumulate substantial quantities of intracellular lipids and carotenoids. In this study, crude glycerol, a by-product of biodiesel production, was used as a carbon source to enhance the accumulation of lipids and carotenoids in the cells. The culture conditions were first optimized using response surface methodology, which revealed that the carotenoid concentration and lipid content improved when the concentration of crude glycerol was 40 g/L. Different fermentation conditions were also investigated: batch, repeated-batch, and fed-batch conditions in a 500 L fermenter. For fed-batch fermentation, the maximum concentrations of biomass, lipids, and carotenoids obtained were 46.32 g/L, 37.65%, and 713.80 mg/L, respectively. A chemical-free carotenoid extraction method was also optimized using high-pressure homogenization and a microfluidizer device. The carotenoids were found to be mostly beta-carotene, which was confirmed by HPLC (high pressure liquid chromatography), LC-MS (liquid chromatography-mass spectrometry), and NMR (nuclear magnetic resonance). The results of this study indicate that crude glycerol can be used as a substrate to produce carotenoids, resulting in enhanced value of this biodiesel by-product.

Algal Carotenoids: Chemistry, Sources, and Application

Recently, the isolation and identification of various biologically active secondary metabolites from algae have been of scientific interest, with particular attention paid to carotenoids, widely distributed in various photosynthetic organisms, including algal species. Carotenoids are among the most important natural pigments, with many health-promoting effects. Since the number of scientific studies on the presence and profile of carotenoids in algae has increased exponentially along with the interest in their potential commercial applications, this review aimed to provide an overview of the current knowledge (from 2015) on carotenoids detected in different algal species (12 microalgae, 21 green algae, 26 brown algae, and 43 red algae) to facilitate the comparison of the results of different studies. In addition to the presence, content, and identification of total and individual carotenoids in various algae, the method of their extraction and the main extraction parameters were also highlighted.

Advanced methods of algal pigments extraction: A review

Algae are exclusively aquatic photosynthetic organisms that are microscopic or macroscopic, unicellular or multicellular and distributed across the globe. They are a potential source of food, feed, medicine and natural pigments. A variety of natural pigments are available from algae including chlorophyll a, b, c d, phycobiliproteins, carotenes and xanthophylls. The xanthophylls include acyloxyfucoxanthin, alloxanthin, astaxanthin, crocoxanthin, diadinoxanthin, diatoxanthin, fucoxanthin, loroxanthin, monadoxanthin, neoxanthin, nostoxanthin, perdinin, Prasinoxanthin, siphonaxanthin, vaucheriaxanthin, violaxanthin, lutein, zeaxanthin, β-cryptoxanthin, while carotenes include echinenone, α-carotene, β-carotene, γ-carotene, lycopene, phytoene, phytofluene. These pigments have applications as pharmaceuticals and nutraceuticals and in the food industry for beverages and animal feed production. The conventional methods for the extraction of pigments are solid-liquid extraction, liquid-liquid extraction and soxhlet extraction. All these methods are less efficient, time-consuming and have higher solvent consumption. For a standardized extraction of natural pigments from algal biomass advanced procedures are in practice which includes Supercritical fluid extraction, Pressurized liquid extraction, Microwave-assisted extraction, Pulsed electric field, Moderate electric field, Ultrahigh pressure extraction, Ultrasound-assisted extraction, Subcritical dimethyl ether extraction, Enzyme assisted extraction and Natural deep eutectic solvents. In the present review, these methods for pigment extraction from algae are discussed in detail.

Algal biorefinery towards decarbonization: Economic and environmental consideration

Algae biomass contains various biological elements, including lipids, proteins, and carbohydrates, making it a viable feedstock for manufacturing biofuels. However, the biggest obstacle to commercializing algal biofuels is their high production costs, primarily related to an algae culture. The extraction of additional high value added bioproducts from algal biomass is thus required to increase the economic viability of producing algae biofuel. This study aims to discuss the economic benefits of a zero-carbon economy and an environmentally sustainable algae resource in decarbonizing the environment through the manufacture of algal-based biofuels from algae biomass for a range of potential uses. In addition, research on the algae biorefineries, with an emphasis on case studies for various cultivation methods, as well as the commercialization of biofuel and bioenergy. Overall, the algal biorefinery offers fresh potential for synthesizing various products.

Recent Advances in Marine Microalgae Production: Highlighting Human Health Products from Microalgae in View of the Coronavirus Pandemic (COVID-19)

Blue biotechnology can greatly help solve some of the most serious social problems due to its wide biodiversity, which includes marine environments. Microalgae are important resources for human needs as an alternative to terrestrial plants because of their rich biodiversity, rapid growth, and product contributions in many fields. The production scheme for microalgae biomass mainly consists of two processes: (I) the Build-Up process and (II) the Pull-Down process. The Build-Up process consists of (1) the super strain concept and (2) cultivation aspects. The Pull-Down process includes (1) harvesting and (2) drying algal biomass. In some cases, such as the manufacture of algal products, the (3) extraction of bioactive compounds is included. Microalgae have a wide range of commercial applications, such as in aquaculture, biofertilizer, bioenergy, pharmaceuticals, and functional foods, which have several industrial and academic applications around the world. The efficiency and success of biomedical products derived from microalgal biomass or its metabolites mainly depend on the technologies used in the cultivation, harvesting, drying, and extraction of microalgae bioactive molecules. The current review focuses on recent advanced technologies that enhance microalgae biomass within microalgae production schemes. Moreover, the current work highlights marine drugs and human health products derived from microalgae that can improve human immunity and reduce viral activities, especially COVID-19.

Recovering Microalgal Bioresources: A Review of Cell Disruption Methods and Extraction Technologies

Microalgae have evolved into a promising sustainable source of a wide range of compounds, including protein, carbohydrates, biomass, vitamins, animal feed, and cosmetic products. The process of extraction of intracellular composites in the microalgae industry is largely determined by the microalgal species, cultivation methods, cell wall disruption techniques, and extraction strategies. Various techniques have been applied to disrupt the cell wall and recover the intracellular molecules from microalgae, including non-mechanical, mechanical, and combined methods. A comprehensive understanding of the cell disruption processes in each method is essential to improve the efficiency of current technologies and further development of new methods in this field. In this review, an overview of microalgal cell disruption techniques and an analysis of their performance and challenges are provided. A number of studies on cell disruption and microalgae extraction are examined in order to highlight the key challenges facing the field of microalgae and their future prospects. In addition, the amount of product recovery for each species of microalgae and the important parameters for each technique are discussed. Finally, pulsed electric field (PEF)-assisted treatments, which are becoming an attractive option due to their simplicity and effectiveness in extracting microalgae compounds, are discussed in detail.

New concept in swine wastewater treatment: development of a self-sustaining synergetic microalgae-bacteria symbiosis (ABS) system to achieve environmental sustainability

Much attention has been paid to developing methods capable of synchronous removal of pollutants from swine wastewater. Due to the natural symbiotic interactions between microalgae and bacteria, the microalgae-bacteria symbiosis (ABS) system has been found to have potential for treating wastewater. However, the corresponding biological mechanisms in the ABS system and the role of dynamic microbial community evolution in pollutant removal systems remain poorly understood. Therefore, we investigate the potential of an ABS system for pollutant removal applications and analyze the bacterial consortium symbiotically combined with Chlorella sp. MA1 and Coelastrella sp. KE4. The NH₄⁺-N and PO₄^3--P removal efficiencies were significantly increased from 12.79% to 99.52% and 35.66% to 96.06% due to biotic interactions between the microalgae and bacteria. The abundance of bacterial taxa and genes related to oxidative stress, cell growth and nitrogen transfer were found to increase in response to photosynthesis, respiration and NH₄⁺-N uptake. Furthermore, pathogen inactivation was induced via microalgae, co-driven by microbial succession under high dissolved oxygen conditions. In this microalgae-enhanced ABS system, the interactions between microalgae and bacteria are established for pathogens elimination and nitrogen cycling, verifying that the ABS system is an effective and environmentally sustainable swine wastewater treatment method.

The oleaginous astaxanthin-producing alga Chromochloris zofingiensis: potential from production to an emerging model for studying lipid metabolism and carotenogenesis

The algal lipids-based biodiesel, albeit having advantages over plant oils, still remains high in the production cost. Co-production of value-added products with lipids has the potential to add benefits and is thus believed to be a promising strategy to improve the production economics of algal biodiesel. Chromochloris zofingiensis, a unicellular green alga, has been considered as a promising feedstock for biodiesel production because of its robust growth and ability of accumulating high levels of triacylglycerol under multiple trophic conditions. This alga is also able to synthesize high-value keto-carotenoids and has been cited as a candidate producer of astaxanthin, the strongest antioxidant found in nature. The concurrent accumulation of triacylglycerol and astaxanthin enables C. zofingiensis an ideal cell factory for integrated production of the two compounds and has potential to improve algae-based production economics. Furthermore, with the advent of chromosome-level whole genome sequence and genetic tools, C. zofingiensis becomes an emerging model for studying lipid metabolism and carotenogenesis. In this review, we summarize recent progress on the production of triacylglycerol and astaxanthin by C. zofingiensis. We also update our understanding in the distinctive molecular mechanisms underlying lipid metabolism and carotenogenesis, with an emphasis on triacylglycerol and astaxanthin biosynthesis and crosstalk between the two pathways. Furthermore, strategies for trait improvements are discussed regarding triacylglycerol and astaxanthin synthesis in C. zofingiensis.

Mechanical Cell Disruption Technologies for the Extraction of Dyes and Pigments from Microorganisms: A Review

The production of pigments using single cell microorganisms is gaining traction as a sustainable alternative to conventional syntheses, which rely, in no negligible proportions, on petrochemicals. In addition to depending on petroleum, these syntheses involved the use of toxic organic solvents, which may be inadequately disposed of across a range of industries, thus compounding the deleterious effects of fossil fuel exploitation. Literature suggests that notable research efforts in the area of sustainable pigment production using single cell microorganisms are focused on the production of pigments coveted for their interesting qualities, which transcend their mere capacity to dye various fabrics both natural and synthetic. As interest in sustainable pigment biosynthesis grows, the need to devise effective and efficient cell disruption processes becomes more pressing given that the viability of pigment biosynthesis is not only dependent on microorganisms’ yield in terms of production, but also on researchers’ ability to recover them. This review chiefly reports findings as to mechanical cell disruption methods, used individually or in various combinations, and their aptitude to recover biosynthetic pigments.

Functionality of Food Components and Emerging Technologies

This review article introduces nutrition and functional food ingredients, explaining the widely cited terms of bioactivity, bioaccessibility, and bioavailability. The factors affecting these critical properties of food components are analyzed together with their interaction and preservation during processing. Ultimately, the effect of emerging (non-thermal) technologies on different food components (proteins, carbohydrates, lipids, minerals, vitamins, polyphenols, glucosinolates, polyphenols, aroma compounds, and enzymes) is discussed in spite of preserving their functional properties. Non-thermal technologies can maintain the bioavailability of food components, improve their functional and technological properties, and increase the recovery yields from agricultural products. However, the optimization of operational parameters is vital to avoid degradation of macromolecules and the oxidation of labile compounds.

Extraction, Properties, and Applications of Bioactive Compounds Obtained from Microalgae

With the increase in the global population, getting new sources of food is essential. One of the solutions can be found in the oceans due to algae. Microalgae are aquatic photosynthetic organisms used mainly due to their variety of bioactive compounds. The consumption of microalgae has been carried out for centuries and is recommended by organizations, such as OMS and FAO, due to its nutritional value and its properties. Based on the existing literature, there is substantial evidence of the nutritional quality of the algae as well as their functional elements. However, much quantification is still necessary, as well as studying possible adverse effects. The present review describes the compounds of alimentary interest present in these algae as well as different extraction techniques assisted by different energetic mechanisms (such as heat, supercritical-fluid, microwave, ultrasound, enzymes, electric field, high hydrostatic pressure, among others). The most challenging and crucial issues are reducing microalgae growth cost and optimizing extraction techniques. This review aimed a better understanding of the uses of microalgae for new researches in nutrition. Since the use of microalgae is still a field in which there is much to discover, it is likely that more benefits will be found in its consumption.

Current and novel approaches to downstream processing of microalgae: A review

Biotechnological application of microalgae cultures at large scale has significant potential in the various fields of biofuels, food and feed, cosmetic, pharmaceutic, environmental remediation and water treatment. Despite this great potential application, industrialisation of microalgae culture and valorisation is still faced with serious remaining challenges in culture scale-up, harvesting and extraction of target molecules. This review presents a general summary of current techniques for harvesting and extraction of biomolecules from microalgae, their relative merits and potential for industrial application. The cell wall composition and its impact on microalgae cell disruption is discussed. Additionally, more recent progress and promising experimental methods and studies are summarised that would allow the reader to further investigate the state of the art. A final survey of energetic assessments of the different techniques is also made. Bead milling and high-pressure homogenisation seem to give clear advantages in terms of target high value compounds extraction from microalgae, with enzyme hydrolysis as a promising emerging technique. Future industrialisation of microalgae for high scale biotechnological processing will require the establishment of universal comparison-standards that would enable easy assessment of one technique against another.

High Homogenization Pressures to Improve Food Quality, Functionality and Sustainability

Interest in high homogenization pressure technology has grown over the years. It is a green technology with low energy consumption that does not generate high CO2 emissions or polluting effluents. Its main food applications derive from its effect on particle size, causing a more homogeneous distribution of fluid elements (particles, globules, droplets, aggregates, etc.) and favoring the release of intracellular components, and from its effect on the structure and configuration of chemical components such as polyphenols and macromolecules such as carbohydrates (fibers) and proteins (also microorganisms and enzymes). The challenges of the 21st century are leading the processed food industry towards the creation of food of high nutritional quality and the use of waste to obtain ingredients with specific properties. For this purpose, soft and nonthermal technologies such as high pressure homogenization have huge potential. The objective of this work is to review how the need to combine safety, functionality and sustainability in the food industry has conditioned the application of high-pressure homogenization technology in the last decade.

Algal biorefinery models with self-sustainable closed loop approach: Trends and prospective for blue-bioeconomy

Microalgae due to its metabolic versatility have received a focal attention in the biorefinery and bioeconomy context. Microalgae products have broad and promising application potential in the domain of renewable fuels/energy, nutraceutical, pharmaceuticals and cosmetics. Biorefining of microalgal biomass in a circular loop with an aim to maximize resource recovery is being considered as one of the sustainable option that will have both economical and environmental viability. The expansive scope of microalgae cultivation with self-sustainability approach was discussed in this communication in the framework of blue-bioeconomy. Microalgae based primary products, cultivation strategies, valorization of microalgae biomass for secondary products and integrated biorefinery models for the production of multi-based products were discussed. The need and prospect of self-sustainable models in closed loop format was also elaborated.

Green Chemistry Extractions of Carotenoids from Daucus carota L.-Supercritical Carbon Dioxide and Enzyme-Assisted Methods

Multiple reviews have been published on various aspects of carotenoid extraction. Nevertheless, none of them focused on the discussion of recent green chemistry extraction protocols, especially for the carotenoids extraction from Daucus carota L. This group of bioactive compounds has been chosen for this review since most of the scientific papers proved their antioxidant properties relevant for inflammation, stress-related disorders, cancer, or neurological and neurodegenerative diseases, such as stroke and Alzheimer's Disease. Besides, carrots constitute one of the most popular sources of carotenoids. In the presented review emphasis has been placed on the supercritical carbon dioxide and enzyme-assisted extraction techniques for the relevant tetraterpenoids. The detailed descriptions of these methods, as well as practical examples, are provided. In addition, the pros and cons of each method and comparison with the standard solvent extraction have been discussed.

Analysis of major carotenoids and fatty acid composition of freshwater microalgae

Considering the nutraceutical properties, the high commercial value from pigments and essential lipids and the environmental sustainability, the purposes of this study were to assess the major carotenoids and fatty acids composition of nine microalgae species as a source of nutraceutical compounds and as fatty raw material for biodiesel production. The carotenoid and fatty acid content were analyzed by high performance liquid chromatography tandem mass spectrometry detection method with atmospheric pressure chemical ionization mode (HPLC/APCI-MS/MS) and by high resolution gas chromatography with flame ionization detector (GC-FID). For the carotenoid analysis, the developed method presented a rapid response, a good chromatographic separation, higher sensitivity and can provides more compounds information due the mass spectrum. Among the microalgae evaluated, Desmodesmus protuberans (10.3 mg g-1), Desmodesmus denticulatus var. linearis (8.43 mg g-1) and Chlamydomonas planctogloea (7.4 mg g-1) are good lutein sources. Coelastrum sphaericum (15.29 mg g-1) and Parachlorella kessleri (22.96 mg g-1) showed high astaxanthin content; the others microalgae species presents low carotenoid content. In addition, Chlorella zofingiensis provides high quantities of γ-linolenic acid (4.3%). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels were lower than 1.1 %. Regarding for biodiesel production, the promising strains are Coelastrum sphaericum and Parachlorella kessleri.

Innovative Alternative Technologies to Extract Carotenoids from Microalgae and Seaweeds

Marine microalgae and seaweeds (microalgae) represent a sustainable source of various bioactive natural carotenoids, including β-carotene, lutein, astaxanthin, zeaxanthin, violaxanthin and fucoxanthin. Recently, the large-scale production of carotenoids from algal sources has gained significant interest with respect to commercial and industrial applications for health, nutrition, and cosmetic applications. Although conventional processing technologies, based on solvent extraction, offer a simple approach to isolating carotenoids, they suffer several, inherent limitations, including low efficiency (extraction yield), selectivity (purity), high solvent consumption, and long treatment times, which have led to advancements in the search for innovative extraction technologies. This comprehensive review summarizes the recent trends in the extraction of carotenoids from microalgae and seaweeds through the assistance of different innovative techniques, such as pulsed electric fields, liquid pressurization, supercritical fluids, subcritical fluids, microwaves, ultrasounds, and high-pressure homogenization. In particular, the review critically analyzes technologies, characteristics, advantages, and shortcomings of the different innovative processes, highlighting the differences in terms of yield, selectivity, and economic and environmental sustainability.