Carotenoids in Microalgae

Absorption, Steady-State Fluorescence and Solvent Effect Studies of Fluorescent Haloarchaeal Bacterioruberin

Fluorescence characterization of halophilic archaeal C50 carotenoid-bacterioruberin extracts was investigated using UV/Vis and steady-state fluorescence spectrophotometry in solvents with different polarity. Different extracts showed maximum absorption and fluorescence wavelengths between 369-536 nm and 540-569 nm. Stokes' shifts varied between 50-79 nm depending on the solvent. In particular, water extract showed significant Stokes' shifts with the increase in polarity index; however, fluorescence wavelength (band position) and shape were found to be independent of polarity. According to the obtained results, it is thought that bacterioruberin will be a new alternative material with increasing applications in optics, biosensor/chemosensor, biotechnology, analytical chemistry and nanotechnology due to its fluorescence properties.

Green and sustainable technologies for extraction of carotenoids from natural sources: a comprehensive review

In recent years, driven by increasing consumer demand for natural and healthy convenient foods, the food industry has been shifting from synthetic to natural products. This shift is also reflected in the growing popularity of non-conventional extraction methods for pigments, which are favored for sustainability and environment-friendliness compared to conventional processes. This review aims to investigate the extraction of carotenoids from a variety of natural sources, including marine sources like fungus, microalgae, and crustaceans, as well as widely studied plants like tomatoes and carrots. Additionally, it delves into the recovery of valuable carotenoids from waste products like pomace and peels, highlighting the nutritional and environmental benefits. The review also emphasizes the role of green solvents such limonene, vegetable oils, ionic liquids, supercritical fluids, and natural deep eutectic solvents in effective and ecologically friendly carotenoid extraction. These technologies support the ideas of a circular and sustainable economy in addition to having a smaller negative impact on the environment. Overall, the present study highlights the crucial importance of green extraction technologies in achieving the dual goals of sustainability and public safety.

Fermentative Production of β-Carotene from Sugarcane Bagasse Hydrolysate by Rhodotorula glutinis CCT-2186

Β-Carotene is a red-orange pigment that serves as a precursor to important pharmaceutical molecules like vitamin A and retinol, making it highly significant in the industrial sector. Consequently, there is an ongoing quest for more sustainable production methods. In this study, glucose and xylose, two primary sugars derived from sugarcane bagasse (SCB), were utilized as substrates for β-carotene production by Rhodotorula glutinis CCT-2186. To achieve this, SCB underwent pretreatment using NaOH, involved different concentrations of total solids (TS) (10%, 15%, and 20%) to remove lignin. Each sample was enzymatically hydrolyzed using two substrate loadings (5% and 10%). The pretreated SCB with 10%, 15%, and 20% TS exhibited glucose hydrolysis yields (%wt) of 93.10%, 91.88%, and 90.77%, respectively. The resulting hydrolysate was employed for β-carotene production under batch fermentation. After 72 h of fermentation, the SCB hydrolysate yielded a β-carotene concentration of 118.56 ± 3.01 mg/L. These findings showcase the robustness of R. glutinis as a biocatalyst for converting SCB into β-carotene.

Ketocarotenoids adonirubin and adonixanthin: Properties, health benefits, current technologies, and emerging challenges

Given their multifaceted roles, carotenoids have garnered significant scientific interest, resulting in a comprehensive and intricate body of literature that occasionally presents conflicting findings concerning the proper characterization, quantification, and bioavailability of these compounds. Nevertheless, it is undeniable that the pursuit of novel carotenoids remains a crucial endeavor, as their diverse properties, functionalities and potential health benefits make them invaluable natural resources in agri-food and health promotion through the diet. In this framework, particular attention is given to ketocarotenoids, viz., astaxanthin (one of them) stands out for its possible multifunctional role as an antioxidant, anticancer, and antimicrobial agent. It has been widely explored in the market and utilized in different applications such as nutraceuticals, food additives, among others. Adonirubin and adonixanthin can be naturally found in plants and microorganisms. Due to the increasing significance of natural-based products and the remarkable opportunity to introduce these ketocarotenoids to the market, this review aims to provide an expert overview of the pros and cons associated with adonirubin and adonixanthin.

Microbial pigments: Sources, current status, future challenges in cosmetics and therapeutic applications

Color serves as the initial attraction and offers a pleasing aspect. While synthetic colorants have been popular for many years, their adverse environmental and health effects cannot be overlooked. This necessitates the search for natural colorants, especially microbial colorants, which have proven and more effective. Pigment-producing microorganisms offer substantial benefits. Natural colors improve product marketability and bestow additional benefits, including antioxidant, antiaging, anticancer, antiviral, antimicrobial, and antitumor properties. This review covers the various types of microbial pigments, the methods to enhance their production, and their cosmetic and therapeutic applications. We also address the challenges faced during the commercial production of microbial pigments and propose potential solutions.

Random mutagenesis of Phaeodactylum tricornutum using ultraviolet, chemical, and X-radiation demonstrates the need for temporal analysis of phenotype stability

We investigated two non-ionising mutagens in the form of ultraviolet radiation (UV) and ethyl methanosulfonate (EMS) and an ionising mutagen (X-ray) as methods to increase fucoxanthin content in the model diatom Phaeodactylum tricornutum. We implemented an ultra-high throughput method using fluorescence-activated cell sorting (FACS) and live culture spectral deconvolution for isolation and screening of potential pigment mutants, and assessed phenotype stability by measuring pigment content over 6 months using high-performance liquid chromatography (HPLC) to investigate the viability of long-term mutants. Both UV and EMS resulted in significantly higher fucoxanthin within the 6 month period after treatment, likely as a result of phenotype instability. A maximum fucoxanthin content of 135 ± 10% wild-type found in the EMS strain, a 35% increase. We found mutants generated using all methods underwent reversion to the wild-type phenotype within a 6 month time period. X-ray treatments produced a consistently unstable phenotype even at the maximum treatment of 1000 Grays, while a UV mutant and an EMS mutant reverted to wild-type after 4 months and 6 months, respectively, despite showing previously higher fucoxanthin than wild-type. This work provides new insights into key areas of microalgal biotechnology, by (i) demonstrating the use of an ionising mutagen (X-ray) on a biotechnologically relevant microalga, and by (ii) introducing temporal analysis of mutants which has substantial implications for strain creation and utility for industrial applications.

Physiological changes of microalga Dunaliella parva under the treatment of PEG, CaCl2

Carotenoids are antioxidants, which reduce various chronic diseases of human, and have many industrial applications. The halophilic Dunaliella parva (D. parva) is rich in carotenoids. The compounds CaCl2 and PEG are the popular metabolic enhancers. To further enhance carotenogenesis, D. parva was treated with two compounds polyethylene glycol (PEG) and CaCl2. Application of CaCl2 and PEG enhanced the carotenoids contents and the antioxidant activities of carotenoids compared to control group (no treatment of CaCl2 or PEG). The highest carotenoids contents were obtained by treating D. parva with 40 ppm CaCl2 (3.11 mg/g dry weight, DW) and 80 ppm PEG (2.78 mg/g DW) compared with control group (1.96 mg/g DW). When D. parva was treated with 40 ppm CaCl2 and 80 ppm PEG, protein contents reached the highest values (90.28 mg/g DW and 89.57 mg/g DW) compared to that of control group (73.42 mg/g DW). The antioxidant activities of carotenoids samples were determined. Generally, the antioxidant activities of carotenoids from D. parva treated with PEG and CaCl2 were superior to that of control group. The antioxidant activities of carotenoids mainly contained reducing power, hydroxyl radical scavenging activity and superoxide radical scavenging activity. The reducing powers of carotenoids extracts from 20 ppm CaCl2 group (2.07%/mg carotenoids) and 120 ppm PEG group (1.59%/mg carotenoids) were significantly higher than that of control group (<1.25%/mg carotenoids). The superoxide radical scavenging activities of carotenoids extracts from 40 ppm CaCl2 group (70.33%/mg carotenoids) and 80 ppm PEG group (65.94%/mg carotenoids) were significantly higher than that of control group (<55%/mg carotenoids). This paper laid a foundation for massive accumulation of carotenoids in microalga D. parva.

Carotenoid enrichment in eggs: From biochemistry perspective

The emergence of safe and functional eggs for consumer acceptance has gained focus. The production of carotenoid-enriched eggs has received attention due to its multifunctional biological properties. Nutritional modification of laying hens' diet can be a strategy to produce such eggs. This review presents the chemistry of carotenoids in nature and eggs, the accumulation process of carotenoids into eggs, and the functions of carotenoids in eggs. Our findings showed that carotenoids can be deposited into the egg and contribute to improving its nutritive value. The biosynthesis, chemical structure, and metabolism pathways of carotenoids lead to the deposition of carotenoids into eggs in their original or metabolized forms. Also, some factors modulate the efficiency of carotenoids in fowls before accumulation into eggs. Carotenoid-enriched eggs may be promising, ensuring the availability of highly nutritive eggs. However, further studies are still needed to comprehend the full metabolism process and the extensive functions of carotenoids in eggs.

Potent carotenoid astaxanthin expands the anti-cancer activity of cisplatin in human prostate cancer cells

Prostate cancer (PCa) is the second most common type of cancer and the sixth cause of death in men worldwide. Radiotherapy and immunotherapy are commonly used in treating PCa, but understanding the crosstalk mechanisms of carcinogenesis and new therapeutic approaches is essential for supporting poor diagnosis and existing therapies. Astaxanthin (ASX) is a member of the xanthophyll family that is an oxygenated derivative of carotenoids whose synthesis is in plant extracts from lycopene. ASX has protective effects on various diseases, such as Parkinson's disease and cancer by showing potent antioxidant and anti-inflammatory properties. However, there is an ongoing need for a detailed investigation of the molecular mechanism of action to expand its therapeutic use. In the present study, we showed the new regulatory role of ASX in PCa cells by affecting the unfolded protein response (UPR) signaling, autophagic activity, epithelial-mesenchymal transition (EMT) and regulating the expression level of angiogenesis-related protein vascular endothelial growth factor A (VEGF-A), proto-oncogene c-Myc and prostate-specific antigen (PSA). Additionally, we determined that it exhibited synergistic action with cisplatin and significantly enhanced apoptotic cell death in PCa cells. Present findings suggest that ASX may be a potent adjuvant therapeutic option in PCa treatment when used alone or combined with chemotherapeutics. Schematic illustration of the biochemical activity of astaxanthin and its combination with cisplatin.

In Silico Methodologies to Improve Antioxidants' Characterization from Marine Organisms

Marine organisms have been reported to be valuable sources of bioactive molecules that have found applications in different industrial fields. From organism sampling to the identification and bioactivity characterization of a specific compound, different steps are necessary, which are time- and cost-consuming. Thanks to the advent of the -omic era, numerous genome, metagenome, transcriptome, metatranscriptome, proteome and microbiome data have been reported and deposited in public databases. These advancements have been fundamental for the development of in silico strategies for basic and applied research. In silico studies represent a convenient and efficient approach to the bioactivity prediction of known and newly identified marine molecules, reducing the time and costs of "wet-lab" experiments. This review focuses on in silico approaches applied to bioactive molecule discoveries from marine organisms. When available, validation studies reporting a bioactivity assay to confirm the presence of an antioxidant molecule or enzyme are reported, as well. Overall, this review suggests that in silico approaches can offer a valuable alternative to most expensive approaches and proposes them as a little explored field in which to invest.

Biological active metabolites from microalgae for healthcare and pharmaceutical industries: A comprehensive review

Microalgae are photoautotrophic microorganisms which comprise of species from several phyla. Microalgae are promising in producing a varieties of products, including food, feed supplements, chemicals, and biofuels. Medicinal supplements derived from microalgae are of a significant market in which compounds such as -carotene, astaxanthin, polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and polysaccharides such as -glucan, are prominent. Microalgae species which are commonly applied for commercial productions include Isochrysis sp., Chaetoceros (Chlorella sp.), Arthrospira sp. (Spirulina Bioactive) and many more. In this present review, microalgae species which are feasible in metabolites production are being summarized. Metabolites produced by microalgae as well as their prospective applications in the healthcare and pharmaceutical industries, are comprehensively discussed. This evaluation is greatly assisting industrial stakeholders, investors, and researchers in making business decisions, investing in ventures, and moving the production of microalgae-based metabolites forward.

Improvement of Lutein and Zeaxanthin Production in Mychonastes sp. 247 by Optimizing Light Intensity and Culture Salinity Conditions

In this study, we sought to improve lutein and zeaxanthin production in Mychonastes sp. 247 and investigated the effect of environmental factors on lutein and zeaxanthin productivity in Mychonastes sp. The basic medium selection and N:P ratio were adjusted to maximize cell growth in one-stage culture, and lutein and zeaxanthin production conditions were optimized using a central composite design for two-stage culture. The maximum lutein production was observed at a light intensity of 60 μE/m²/s and salinity of 0.49%, and the maximum zeaxanthin production was observed at a light intensity of 532 μE/m²/s and salinity of 0.78%. Lutein and zeaxanthin production in the optimized medium increased by up to 2 and 2.6 folds, respectively, compared to that in the basic medium. Based on these results, we concluded that the optimal conditions for lutein and zeaxanthin production are different and that optimization of light intensity and culture salinity conditions may help increase carotenoid production. This study presents a useful and potential strategy for optimizing microalgal culture conditions to improve the productivity of lutein and zeaxanthin, which has applications in the functional food field.

Recent Advances in Supercritical CO2 Extraction of Pigments, Lipids and Bioactive Compounds from Microalgae

Supercritical CO₂ extraction is a green method that combines economic and environmental benefits. Microalgae, on the other hand, is a biomass in abundance, capable of providing a vast variety of valuable compounds, finding applications in the food industry, cosmetics, pharmaceuticals and biofuels. An extensive study on the existing literature concerning supercritical fluid extraction (SFE) of microalgae has been carried out focusing on carotenoids, chlorophylls, lipids and fatty acids recovery, as well as the bioactivity of the extracts. Moreover, kinetic models used to describe SFE process and experimental design are included. Finally, biomass pretreatment processes applied prior to SFE are mentioned, and other extraction methods used as benchmarks are also presented.

Sustainable Production of Pigments from Cyanobacteria

Pigments are intensely coloured compounds used in many industries to colour other materials. The demand for naturally synthesised pigments is increasing and their production can be incorporated into circular bioeconomy approaches. Natural pigments are produced by bacteria, cyanobacteria, microalgae, macroalgae, plants and animals. There is a huge unexplored biodiversity of prokaryotic cyanobacteria which are microscopic phototrophic microorganisms that have the ability to capture solar energy and CO2 and use it to synthesise a diverse range of sugars, lipids, amino acids and biochemicals including pigments. This makes them attractive for the sustainable production of a wide range of high-value products including industrial chemicals, pharmaceuticals, nutraceuticals and animal-feed supplements. The advantages of cyanobacteria production platforms include comparatively high growth rates, their ability to use freshwater, seawater or brackish water and the ability to cultivate them on non-arable land. The pigments derived from cyanobacteria and microalgae include chlorophylls, carotenoids and phycobiliproteins that have useful properties for advanced technical and commercial products. Development and optimisation of strain-specific pigment-based cultivation strategies support the development of economically feasible pigment biorefinery scenarios with enhanced pigment yields, quality and price. Thus, this chapter discusses the origin, properties, strain selection, production techniques and market opportunities of cyanobacterial pigments.

Recent Progress on Carotenoids Production from Microalgae: A review

The color of fruits and green vegetables is attributed to a pigment known as carotenoids. On the basis of presence and absence of oxygen, carotenoids are divided into two categories; carotenes which do not contain oxygen and xanthophylls which are oxygen carrier. Carotenoids are not only good anti-oxidant agents; they also exhibit anti-tumor properties. The structure of carotenoids consists of eight isoprene units, which forms a chain consisting of conjugated double bonds. The presence of conjugated double bond in carotenoids neutralize free radicals by accepting electrons from them. Till now, most of the carotenoids commercially available are produced chemically however, microalgae are a good source of carotenoids. Microalgae can produce the carotenoids in abundance using two-stage cultivation strategies. In first phase, microalgae are given with optimal growth conditions for maximum production of biomass, on the other hand, keeping the second phase for the storage of lipids or carotenoids in unfavorable conditions. The production of carotenoids in two-stage approach is increased by many times than the conventional single phase cultivation method. Carotenoids have many industrial applications.

Prospects of dietary seaweeds and their bioactive compounds in sustainable poultry production systems: A symphony of good things?

Modern poultry production systems face numerous economic, environmental, and social sustainability challenges that threaten their viability and acceptability as a major source of animal protein. As scientists and producers scramble to find cost-effective and socially acceptable solutions to these challenges, the dietary use of marine macroalgae (seaweeds) could be an ingenious option. Indeed, the incredible array of nutritive and bioactive compounds present in these macroscopic marine organisms can be exploited as part of sustainable poultry production systems of the future. Incorporating seaweeds in poultry diets could enhance feed utilization efficiency, growth performance, bird health, meat stability and quality, and consumer and environmental health. Theoretically, these benefits are mediated through the putative antiviral, antibacterial, antifungal, antioxidant, anticarcinogenic, anti-inflammatory, anti-allergic, antithrombotic, neuroprotective, hypocholesterolemic, and hypoglycemic properties of seaweed bioactive compounds. Despite this huge potential, exploitation of seaweed for poultry production appears to be constrained by a variety of factors such as high fibre, phenolics, and ash content. In addition, conflicting findings are often reported when seaweeds or their extracts are used in poultry feeding trials. Therefore, the purpose of this review paper is to collate information on the production, phytochemical components, and nutritive value of different seaweed species. It provides an overview ofin vivoeffects of dietary seaweeds as measured by nutrient utilization efficiency, growth performance, and product quality and stability in poultry. The utility of dietary seaweeds in sustainable poultry production systems is explored, while gaps that require further research are highlighted. Finally, opportunities that exist for enhancing the utility of seaweeds as a vehicle for sustainable production of functional poultry products for better global food and nutrition security are presented.

Kinetic modeling and process analysis for photo-production of β-carotene in Dunaliella salina

Dunaliella salina is a green microalga with the great potential to generate natural β-carotene. However, the corresponding mathematical models to guide optimized production of β-carotene in Dunaliella salina (D. salina) are not yet available. In this study, dynamic models were proposed to simulate effects of environmental factors on cell growth and β-carotene production in D. salina using online monitoring system. Moreover, the identification model of the parameter variables was established, and an adaptive particle swarm optimization algorithm based on parameter sensitivity analysis was constructed to solve the premature problem of particle swarm algorithm. The proposed kinetic model is characterized by high accuracy and predictability through experimental verification, which indicates its competence for future process design, control, and optimization. Based on the model established in this study, the optimal environmental factors for both β-carotene production and microalgae growth were identified. The approaches created are potentially useful for microalga Dunaliella salina cultivation and high-value β-carotene production.

Multifaceted strategies for economic production of microalgae Haematococcus pluvialis-derived astaxanthin via direct conversion of CO2

Owing to its strong antioxidant properties, astaxanthin has a high market price in the nutraceutical and pharmaceutical fields, and its demand is increasing. Furthermore, with an increase in the demand for green technology, astaxanthin production through direct CO₂ conversion using the autotrophic green microalga Haematococcus pluvialis as a bio-platform has received much attention. Large-scale outdoor cultivation of H. pluvialis using waste CO₂ sources and sunlight can secure sustainability and improve economic efficiency. However, low strain performance, reduced light utilization because of increased cell density, and inefficient transfer of gaseous CO₂ into liquid culture broth hinder its large-scale commercialization of astaxanthin. Herein, we presented a multifaceted strategy, including the development of high-efficiency strains, a culture system for astaxanthin accumulation, and astaxanthin extraction from biomass, for economically producing astaxanthin from H. pluvialis through direct CO₂ conversion. Future perspectives were presented by comparing and analyzing various previous studies conducted using the latest technology.

Strategies for enhancing terpenoids accumulation in microalgae

Terpenoids represent one of the largest class of chemicals in nature, which play important roles in food and pharmaceutical fields due to diverse biological and pharmacological activities. Microorganisms are recognized as a promising source of terpenoids due to its short growth cycle and sustainability. Importantly, microalgae can fix inorganic carbon through photosynthesis for the growth of themselves and the biosynthesis of various terpenoids. Moreover, microalgae possess effective biosynthesis pathways of terpenoids, both the eukaryotic mevalonic acid (MVA) pathway and the prokaryotic methyl-D-erythritol 4-phosphate (MEP) pathway. In recent years, various genetic engineering strategies have been applied to increase target terpenoid yields, including overexpression of the rate-limited enzymes and inhibition of the competing pathways. However, since gene-editing tools are only built in some model microalgae, fermentation strategies that are easier to be operated have been widely successful in promoting the production of terpenoids, such as changing culture conditions and addition of chemical additives. In addition, an economical and effective downstream process is also an important consideration for the industrial production of terpenoids, and the solvent extraction and the supercritical fluid extraction method are the most commonly used strategies, especially in the industrial production of β-carotene and astaxanthin from microalgae. In this review, recent advancements and novel strategies used for terpenoid production are concluded and discussed, and new insights to move the field forward are proposed. KEY POINTS: • The MEP pathway is more stoichiometrically efficient than the MVA pathway. • Advanced genetic engineering and fermentation strategies can increase terpene yield. • SFE has a higher recovery of carotenoids than solvent extraction.

Current developments on the application of microbial carotenoids as an alternative to synthetic pigments

Microbial carotenoids have attracted rising interest from several industries as a sustainable alternative to substitute the synthetic ones. Traditionally, carotenoids available in the market are obtained by the chemical route using nonrenewable sources (petrochemicals), revealing the negative impact on the environment and consumers. The most promising developments in the upstream and downstream processes of microbial carotenoids are reviewed in this work. The use of agro-based raw materials for bioproduction, and alternative solvents such as biosolvents, deep eutectic solvents, and ionic liquids for the recovery/polishing of microbial carotenoids were also reviewed. The principal advances in the field, regarding the biorefinery and circular economy concepts, were also discussed for a better understanding of the current developments. This review provides comprehensive overview of the hot topics in the field besides an exhaustive analysis of the main advantages/drawbacks and opportunities regarding the implementation of microbial carotenoids in the market.

In vitro bioaccessibility of macular xanthophylls from commercial microalgal powders of Arthrospira platensis and Chlorella pyrenoidosa

The bioaccessibility of the major carotenoids present in two commercial microalgal supplements in powder form was investigated through a standardized in vitro digestion method. The dried biomass of Arthrospira platensis contained β-carotene (36.8 mg/100 g) and zeaxanthin (20.8 mg/100 g) as the main carotenoids as well as a high content of saturated fatty acids (61% of total fatty acids), whereas that of Chlorella pyrenoidosa was rich in lutein (37.8 mg/100 g) and had a high level of unsaturated fatty acids (65% of total fatty acids). In the case of the latter, lutein bioaccessibility was not statistically enhanced after the replacement of porcine bile extract with bovine bile extract in the in vitro digestion protocol and after the addition of coconut oil (17.8% as against to 19.2% and 19.2% vs. 18.5%, respectively). In contrast, the use of bovine bile extract along with co-digestion with coconut oil significantly enhanced the bioaccessibility of zeaxanthin from A. platensis, reaching the highest bioaccessibility of 42.8%.

ROS Induce β-Carotene Biosynthesis Caused by Changes of Photosynthesis Efficiency and Energy Metabolism in Dunaliella salina Under Stress Conditions

The unicellular alga Dunaliella salina is regarded as a promising cell factory for the commercial production of β-carotene due to its high yield of carotenoids. However, the underlying mechanism of β-carotene accumulation is still unclear. In this study, the regulatory mechanism of β-carotene accumulation in D. salina under stress conditions was investigated. Our results indicated that there is a significant positive correlation between the cellular ROS level and β-carotene content, and the maximum quantum efficiency (F_v/F_m) of PSII is negatively correlated with β-carotene content under stress conditions. The increase of ROS was found to be coupled with the inhibition of F_v/F_m of PSII in D. salina under stress conditions. Furthermore, transcriptomic analysis of the cells cultivated with H₂O₂ supplementation showed that the major differentially expressed genes involved in β-carotene metabolism were upregulated, whereas the genes involved in photosynthesis were downregulated. These results indicated that ROS induce β-carotene accumulation in D. salina through fine-tuning genes which were involved in photosynthesis and β-carotene biosynthesis. Our study provided a better understanding of the regulatory mechanism involved in β-carotene accumulation in D. salina, which might be useful for overaccumulation of carotenoids and other valuable compounds in other microalgae.

The effect of microplastics pollution in microalgal biomass production: A biochemical study

Microplastics (MPs) are widely spread throughout aquatic systems and water bodies. Given that water quality is one of the most important parameters in the microalgal-based industry, it is critical to assess the biochemical impact of short- and long-term exposure to MPs pollution. Here, the microalga Phaeodactylum tricornutum was exposed to water contaminated with 0.5 and 50 mg L^-1 of polystyrene (PS) and/or polymethyl methacrylate (PMMA). Results show that the microalgal cultures exposed to lower concentrations of PS displayed a growth enhancement of up to 73% in the first stage (days 3-9) of the exponential growth phase. Surprisingly, and despite the fact that long-term exposure to MPs contamination did not impair microalgal growth, a steep decrease in biomass production (of up to 82%) was observed. The production of photosynthetic pigments was shown to be pH-correlated during the full growth cycle, but cell density-independent in later stages of culturing. The extracellular carbohydrates production exhibited a major decrease during long-term exposure. Still, the production of extracellular proteins was not affected by the presence of MPs. This pilot laboratory-scale study shows that the microalgal exposure to water contaminated with MPs disturbs its biochemical equilibrium in a time-dependent manner, decreasing biomass production. Thus, microalgal industry-related consequences derived from the use of MPs-contaminated water are a plausible possibility.

High-level β-carotene production from xylose by engineered Saccharomyces cerevisiae without overexpression of a truncated HMG1 (tHMG1)

β-Carotene is a natural pigment and health-promoting metabolite, and has been widely used in the nutraceutical, feed, and cosmetic industries. Here, we engineered a GRAS yeast Saccharomyces cerevisiae to produce β-carotene from xylose, the second most abundant and inedible sugar component of lignocellulose biomass. Specifically, a β-carotene biosynthetic pathway containing crtYB, crtI, and crtE from Xanthophyllomyces dendrorhous was introduced into a xylose-fermenting S. cerevisiae. The resulting strain produced β-carotene from xylose at a titer threefold higher than from glucose. Interestingly, overexpression of tHMG1, which has been reported as a critical genetic perturbation to enhance metabolic fluxes in the mevalonate pathway and β-carotene production in yeast when glucose is used, did not further improve the production of β-carotene from xylose. Through fermentation profiling, metabolites analysis, and transcriptional studies, we found the advantages of using xylose as a carbon source, instead of glucose, for β-carotene production to be a more respiratory feature of xylose consumption, a larger cytosolic acetyl-CoA pool, and an upregulated expression level of rate-limiting genes in the β-carotene-producing pathway, including ACS1 and HMG1. As a result, 772.8 mg/L of β-carotene was obtained in a fed-batch bioreactor culture with xylose feeding. Considering the inevitable large scale production of xylose when cellulosic biomass-based bioeconomy is implemented, our results suggest xylose utilization is a promising strategy for overproduction of carotenoids and other isoprenoids in engineered S. cerevisiae.

Astaxanthin in Liver Health and Disease: A Potential Therapeutic Agent

Astaxanthin is a carotenoid derived from oxygen-containing non-vitamin A sources and is mainly obtained from marine organisms. Studies have demonstrated that astaxanthin is a natural antioxidant product and it is widely used in the fields of medicine, health-care products and cosmetics. Studies have shown that astaxanthin has important preventive and therapeutic effects on liver fibrosis, non-alcoholic fatty liver, liver cancer, drug and ischemia-induced liver injury, and its mechanism is related to antioxidant and anti-inflammatory activities, and the regulation of multiple signaling pathways. In this review, we discuss the latest data on astaxanthin in the prevention and treatment of liver diseases. An understanding of the structure, source and mechanism of action of astaxanthin in the body would not only provide a theoretical basis for its clinical application but could also have important significance in screening and improving related compounds for the treatment of liver diseases.

Cloning, expression, and characterization of a novel plant type cryptochrome gene from the green alga Haematococcus pluvialis

A full-length cDNA sequence of plant type CRY (designated Hae-P-CRY) was cloned from the green alga Haematococcus pluvialis. The cDNA sequence was 3608 base pairs (bp) in length, which contained a 2988-bp open reading frame encoding 995 amino acids with molecular mass of 107.7 kDa and isoelectric point of 6.19. Multiple alignment analysis revealed that the deduced amino acid sequence of Hae-P-CRY shared high identity of 47-66% with corresponding plant type CRYs from other eukaryotes. The catalytic motifs of plant type CRYs were detected in the amino acid sequence of Hae-P-CRY including the typical PHR and CTE domains. Phylogenetic analysis showed that the Hae-P-CRY was grouped together with other plant type CRYs from green algae and higher plants, which distinguished from other distinct groups. The transcriptional level of Hae-P-CRY was strongly decreased after 0-4 h under HL stress. In addition, the Hae-P-CRY gene was heterologously expressed in Escherichia coli BL21 (DE3) and successfully purified. The typical spectroscopic characteristics of plant type CRYs were present in Hae-P-CRY indicated that it may be an active enzyme, which provided valuable clue for further functional investigation in the green alga H. pluvialis. These results lay the foundation for further function and interaction protein identification involved in CRYs mediated signal pathway under HL stress in H. pluvialis.

Deciphering Pathways for Carotenogenesis in Haloarchaea

Bacterioruberin and its derivatives have been described as the major carotenoids produced by haloarchaea (halophilic microbes belonging to the Archaea domain). Recently, different works have revealed that some haloarchaea synthetize other carotenoids at very low concentrations, like lycopene, lycopersene, cis- and trans-phytoene, cis- and trans-phytofluene, neo-β-carotene, and neo-α-carotene. However, there is still controversy about the nature of the pathways for carotenogenesis in haloarchaea. During the last decade, the number of haloarchaeal genomes fully sequenced and assembled has increased significantly. Although some of these genomes are not fully annotated, and many others are drafts, this information provides a new approach to exploring the capability of haloarchaea to produce carotenoids. This work conducts a deeply bioinformatic analysis to establish a hypothetical metabolic map connecting all the potential pathways involved in carotenogenesis in haloarchaea. Special interest has been focused on the synthesis of bacterioruberin in members of the Haloferax genus. The main finding is that in almost all the genus analyzed, a functioning alternative mevalonic acid (MVA) pathway provides isopentenyl pyrophosphate (IPP) in haloarchaea. Then, the main branch to synthesized carotenoids proceeds up to lycopene from which β-carotene or bacterioruberin (and its precursors: monoanhydrobacterioriberin, bisanhydrobacterioruberin, dihydrobisanhydrobacteriuberin, isopentenyldehydrorhodopsin, and dihydroisopenthenyldehydrorhodopsin) can be made.

High production of carotenoids by the green microalga Asterarcys quadricellulare PUMCC 5.1.1 under optimized culture conditions

Since carotenoids are important as natural colorants, antioxidants, neutraceutics and pharmaceutics, the aim of the present study was to find a new good source of these pigments. We hereby report a green microalga Asterarcys quadricellulare PUMCC 5.1.1 as a new and good producer of carotenoids. The organism produced 35±1.75 μg carotenoids mg-1 dry biomass during stationary phase in control cultures. The growth and carotenoids production by the test microalga were optimized by varying nutrient growth media, pH, nitrogen and phosphate source, salinity, light quality, intensity and duration. The optimized conditions for carotenoid production were: Bold basal (BB) medium with pH 8.5, containing with10 mM nitrate, 3.5 mM phosphate and 0.17 mM salinity and illuminated with blue light with 60 μmol m-2 s-1 photon flux light intensity. Cultivation of cultures in the above mentioned optimized conditions resulted in nearly 3.0 fold increase in carotenoid production compared to the control cultures grown in unmodified BB medium. Using HPTLC, four carotenoids have been identified as β-carotene, lutein, astaxanthin and canthaxanthin. Further, carotenoids were also separated and purified by flash chromatography and the amounts of purified carotenoids were determined by HPLC. The organism produced 47.0, 28.7, 15.5 and 14.0 μg β-carotene, lutein, astaxanthin and canthaxanthin mg-1 dry biomass, respectively, under optimized conditions. The amount of total carotenoids (118 μg mg-1 dry biomass) produced by Asterarcys quadricellulare PUMCC 5.1.1 under optimized culture conditions was significantly higher than control cultures. Thus, this microalgal strain is a promising candidate for carotenoid production at commercial level.

Deesterification of astaxanthin and intermediate esters from Haematococcus pluvialis subjected to stress

Haematococcus pluvialis is the richest biological source of astaxanthin under unfavorable growing conditions. Many reports have discussed the optimal astaxanthin extraction methods. Free-astaxanthin could be still hindered by microalgae extracts composition or by prolonged extraction times. In this study we evaluated the effect of enzymolysis and saponification deesterification processes of astaxanthin and its carotenoid precursors under high irradiance and nitrogen deprivation stress time conditions. Results showed that cholesterol esterase facilitated astaxanthin deesterification (975.65 μg mg^-1 DW) while saponification positively affected zeaxanthin (1038.68 μg mg^-1 DW).

Eminence of Microbial Products in Cosmetic Industry

Cosmetology is the developing branch of science, having direct impact on the society. The cosmetic sector is interested in finding novel biological alternatives which can enhance the product attributes as well as it can substitute chemical compounds. Many of the compounds are having biological origin and are acquire from bacteria, fungi, and algae. A range of biological compounds, like bio-surfactant, vitamins, antioxidants, pigments, enzymes, peptides have promising features and beneficial properties. Moreover, these products can be produced commercially with ease. The review will encompass the importance and use of microbial compounds for new cosmetic formulations as well as products associated with it.

The lipid biochemistry of eukaryotic algae

Algal lipid metabolism fascinates both scientists and entrepreneurs due to the large diversity of fatty acyl structures that algae produce. Algae have therefore long been studied as sources of genes for novel fatty acids; and, due to their superior biomass productivity, algae are also considered a potential feedstock for biofuels. However, a major issue in a commercially viable "algal oil-to-biofuel" industry is the high production cost, because most algal species only produce large amounts of oils after being exposed to stress conditions. Recent studies have therefore focused on the identification of factors involved in TAG metabolism, on the subcellular organization of lipid pathways, and on interactions between organelles. This has been accompanied by the development of genetic/genomic and synthetic biological tools not only for the reference green alga Chlamydomonas reinhardtii but also for Nannochloropsis spp. and Phaeodactylum tricornutum. Advances in our understanding of enzymes and regulatory proteins of acyl lipid biosynthesis and turnover are described herein with a focus on carbon and energetic aspects. We also summarize how changes in environmental factors can impact lipid metabolism and describe present and potential industrial uses of algal lipids.

A hypothesis about the origin of carotenoid lipid droplets in the green algae Dunaliella and Haematococcus

Hypercarotenogenesis in green algae evolved by mutation of PSY that increased its transcription at high light, disintegration of the eyespot in Dunaliella and acquisition of the capacity to export carotenoids from chloroplasts in Haematococcus. Carotenoids (Car) are lipid-soluble pigments synthesized in plants, algae, bacteria and fungi. Car have strong antioxidative properties and as such are utilized to reduce the danger of different diseases in humans. Two green microalgae are utilized as rich natural sources for Car: Dunaliella salina/bardawil accumulates 10% (w/w) β-carotene (βC), which is also pro-vitamin A, and Haematococcus pluvialis accumulates 4% (w/w) astaxanthin (Ast), the strongest antioxidant among Car. D. bardawil accumulates βC in plastoglobules within the chloroplast, whereas H. pluvialis deposits Ast in cytoplasmic lipid droplets (CLD). In this review we compare the hypercarotenogenic responses (HCR) in Dunaliella and in Haematococcus and try to outline hypothetical evolutionary pathways for its origin. We propose that a mutation in phytoene synthetase that increased its transcription level in response to high light stress had a pivotal role in the evolution of the HCR. Proteomic analyses indicated that in D. bardawil/salina the HCR evolved from dissociation and amplification of eyespot lipid globules. The more robust HCR in algae that accumulate carotenoids in CLD, such as H. pluvialis, required also acquisition of the capacity to export βC out of the chloroplast and its enzymatic conversion into Ast.

Production and extraction of carotenoids produced by microorganisms

Carotenoids are a group of isoprenoid pigments naturally synthesized by plants and microorganisms, which are applied industrially in food, cosmetic, and pharmaceutical product formulations. In addition to their use as coloring agents, carotenoids have been proposed as health additives, being able to prevent cancer, macular degradation, and cataracts. Moreover, carotenoids may also protect cells against oxidative damage, acting as an antioxidant agent. Considering the interest in greener and sustainable industrial processing, the search for natural carotenoids has increased over the last few decades. In particular, it has been suggested that the use of bioprocessing technologies can improve carotenoid production yields or, as a minimum, increase the efficiency of currently used production processes. Thus, this review provides a short but comprehensive overview of the recent biotechnological developments in carotenoid production using microorganisms. The hot topics in the field are properly addressed, from carotenoid biosynthesis to the current technologies involved in their extraction, and even highlighting the recent advances in the marketing and application of "microbial" carotenoids. It is expected that this review will improve the knowledge and understanding of the most appropriate and economic strategies for a biotechnological production of carotenoids.

A global perspective on carotenoids: Metabolism, biotechnology, and benefits for nutrition and health

Carotenoids are lipophilic isoprenoid compounds synthesized by all photosynthetic organisms and some non-photosynthetic prokaryotes and fungi. With some notable exceptions, animals (including humans) do not produce carotenoids de novo but take them in their diets. In photosynthetic systems carotenoids are essential for photoprotection against excess light and contribute to light harvesting, but perhaps they are best known for their properties as natural pigments in the yellow to red range. Carotenoids can be associated to fatty acids, sugars, proteins, or other compounds that can change their physical and chemical properties and influence their biological roles. Furthermore, oxidative cleavage of carotenoids produces smaller molecules such as apocarotenoids, some of which are important pigments and volatile (aroma) compounds. Enzymatic breakage of carotenoids can also produce biologically active molecules in both plants (hormones, retrograde signals) and animals (retinoids). Both carotenoids and their enzymatic cleavage products are associated with other processes positively impacting human health. Carotenoids are widely used in the industry as food ingredients, feed additives, and supplements. This review, contributed by scientists of complementary disciplines related to carotenoid research, covers recent advances and provides a perspective on future directions on the subjects of carotenoid metabolism, biotechnology, and nutritional and health benefits.

Industrial potential of carotenoid pigments from microalgae: Current trends and future prospects

Microalgae are rich source of various bioactive molecules such as carotenoids, lipids, fatty acids, hydrocarbons, proteins, carbohydrates, amino acids, etc. and in recent Years carotenoids from algae gained commercial recognition in the global market for food and cosmeceutical applications. However, the production of carotenoids from algae is not yet fully cost effective to compete with synthetic ones. In this context the present review examines the technologies/methods in relation to mass production of algae, cell harvesting for extraction of carotenoids, optimizing extraction methods etc. Research studies from different microalgal species such as Spirulina platensis, Haematococcus pluvialis, Dunaliella salina, Chlorella sps., Nannochloropsis sps., Scenedesmus sps., Chlorococcum sps., Botryococcus braunii and Diatoms in relation to carotenoid content, chemical structure, extraction and processing of carotenoids are discussed. Further these carotenoid pigments, are useful in various health applications and their use in food, feed, nutraceutical, pharmaceutical and cosmeceutical industries was briefly touched upon. The commercial value of algal carotenoids has also been discussed in this review. Possible recommendations for future research studies are proposed.

Adaptive Laboratory Evolution for Enhanced Carotenoid Production in Microalgae

In order to produce natural pigments with competitive prices, algal strains employed in industrial production need to be improved for increasing the productivity of valuable metabolites, thereby reducing the overall production cost. Adaptive laboratory evolution (ALE) is a traditional method for strain improvement, which has been effectively utilized in bacteria and fungi. With the growing interest in algal biotechnology, attempts have recently been put forward to improve microalgal strains with ALE approach. This chapter describes a stepwise adaptive evolution strategy that enhances carotenoid yield from microalgae.

Markers of Hypoxia and Oxidative Stress in Aging Volunteers Ingesting Lycosomal Formulation of Dark Chocolate Containing Astaxanthin

OBJECTIVE

To determine if ingestion of lycosome-formulated dark chocolate (DC) containing astaxanthin (ASTX) improves bioavailability of ASTX and affects markers of hypoxia and oxidative stress in aging individuals.

DESIGN

Randomized, blinded, four-arm, prospective study.

SETTINGS

Lycotec Ltd, Cambridge, United Kingdom and Institute of Cardiology, Saratov, Russian Federation.

PARTICIPANTS

32 healthy individuals aged 60-70 years with confirmed signs of oxidative stress (increased serum levels of oxidized LDL and malonic dialdehyde) randomized into four study groups (8 volunteers each).

INTERVENTION

Volunteers of first group were given orally 10 gr of dark chocolate (DC). Individuals from the second group received 7 mg of astaxanthin (ASTX). Third group of volunteers was supplemented with 10 gr of DC and 7 mg of ASTX ingested simultaneously as two separate formulations. Last group of the individuals was given 10 gr of a lycosomal formulation of DC containing 7 mg of co-crystalized ASTX (L-DC-ASTX), a newly developed highly bioavailable nutraceutical composition of DC containing 2 groups of antioxidants (cocoa flavanols and ASTX). All formulations were given orally, once daily for a month.

MEASUREMENTS

Serum ASTX was measured by high-performance liquid chromatography. Nitric oxide, malonic dialdehyde and oxidized LDL were quantified spectrophotometrically. Oxygenation parameters were evaluated by near-infrared spectroscopy.

RESULTS

One month ingestion of singular formulation of ASTX lead to a 20 fold buildup in serum ASTX level whereas the 4 week ingestion of L-DC-ASTX formulation was accompanied by more prominent accumulation of ASTX in serum (a 40 fold increase over the basal values) at the same daily dose of ASTX. Both antioxidants taken separately decreased serum levels of oxidized LDL and malonic dialdehyde. However effect of L-DC-ASTX formulation was more prominent. ASTX ingested alone caused a borderline increase (p=0.054) in serum nitric oxide (NO) levels, whereas DC ingestion lead to small but statistically significant increase in serum NO concentration. Higher values of NO level were seen after co-ingestion of DC and ASTX, especially in case of L-DC-ASTX formulation suggesting additive/synergistic effects of DC and ASTX on nitric oxide production. These changes were in agreement with the increase in plasma oxygen transport and tissue oxygen saturation seen in the volunteers supplemented with L-DC-ASTX formulation.

CONCLUSION

The nutraceutical formulation of DC and ASTX with an enhanced bioavailability of ASTX can be efficiently used for the correction of oxidative status in aging individuals.

Microalgae, old sustainable food and fashion nutraceuticals

Microalgae have been used for centuries to provide nourishment to humans and animals, only very recently they have become much more widely cultured and harvested at large industrial scale. This paper reviews the potential health benefits and nutrition provided by microalgae whose benefits are contributing to expand their market. We also point out several key challenges that remain to be addressed in this field.