A review of natural astaxanthin production in a circular bioeconomy context using Paracoccus carotinifaciens

Microbial bacterioruberin: The new C50 carotenoid player in food industries

The demand for natural products has significantly increased, driving interest in carotenoids as bioactive compounds for both human and animal consumption. Carotenoids, natural pigments with several biological properties, like antioxidant and antimicrobial, are increasingly preferred over synthetic colorants by the consumers (chemophobia). The global carotenoid market is projected to reach US$ 2.45 billion by 2034, driven by consumer preferences for natural ingredients and regulatory restrictions on synthetic products. Among carotenoids, bacterioruberin (BR), a C50 carotenoid naturally found in microbial hyperhalophilic archaea and in moderate halophilic archaea, stands out for its exceptional antioxidant capabilities, surpassing even well-known carotenoids like astaxanthin. BR's and its derivatives unique structure, with 13 conjugated double bonds and four -OH groups, contributes to its potent antioxidant activity and potential applications in food, feed, supplements, pharmaceuticals, and cosmeceuticals. This review explores BR's chemical and biological properties, upstream and downstream technologies, analytical techniques, market applications, and prospects in the colorants industry. While BR is not intended to replace existing carotenoids, its inclusion enriches the range of natural products available to meet the rising demand for natural alternatives. Furthermore, BR's promising antioxidant capacity positions it as a key player in the future carotenoid market, offering diverse industries a natural and potent alternative for several applications.

Whole genome sequence of Paracoccus sp. NFXS7, a carotenoid-producing bacterium isolated from a marine saltern

The study presents the whole genome sequence of the carotenoid-producing Paracoccus sp. NFXS7, isolated from a marine saltern in Setúbal, Portugal. The carotenoid-producing strain NFXS7 contains homologs of the crt genes involved in astaxanthin biosynthesis, making it a promising candidate for biotechnological applications.

Advances in microbial astaxanthin production

This work explores astaxanthin (AXT), a valuable xanthophyll ketocarotenoid pigment with significant health benefits and diverse applications across various industries. It discusses the prevalence of synthetic AXT, and the development of natural-based alternatives derived from microorganisms such as microalgae, bacteria, and yeast. The chapter examines the potential of microbial AXT production, highlighting the advantages and challenges associated with natural AXT. Key microorganisms like Haematococcus pluvialis, Paracoccus carotinifaciens, and Phaffia rhodozyma are emphasized for their role in commercially producing this valuable ketocarotenoid. The narrative covers the complexities and opportunities in microbial AXT production, from cell structure implications to downstream processing strategies. Additionally, the chapter addresses current applications, commercialization trends, and market dynamics of natural microbial AXT, emphasizing the importance of cost-effective production, regulatory compliance, and technological advancements to reduce the market cost of the final product. As demand for natural microbial-based AXT rises, this chapter envisions a future where research, innovation, and collaboration drive sustainable and competitive microbial AXT production, fostering growth in this dynamic market.

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.

Tailor-made solvents for microbial carotenoids recovery

In recent years, microbial carotenoids have emerged as a promising alternative for the pharmaceutical and food industries, particularly in promoting human health due to their potent antioxidant and antimicrobial properties. Microbial carotenoids, particularly those produced by yeast, bacteria, and microalgae, are synthesized intracellularly, requiring the use of solvents for their effective extraction and recovery. The conventional use of toxic volatile organic solvents (VOCs) like hexane, petroleum ether, and dimethyl sulfoxide in the extraction of microbial carotenoids has been common. However, ongoing research is introducing innovative, non-toxic, environmentally friendly tailor-made solvents, such as ionic liquids (IL) and deep eutectic solvents (DES), indicating a new era of cleaner and biocompatible technologies. This review aims to highlight recent advancements in utilizing IL and DES for obtaining carotenoids from microorganisms. Additionally, we explore the utilization of in silico tools designed to determine the solubilities of microbial carotenoids in tailor-made DES and ILs. This presents a promising alternative for the scientific community, potentially reducing the need for extensive experimental screening of solvents for the recovery of microbial carotenoids in the separation processing. According to our expert perspective, both IL and DES exhibit a plethora of exceptional attributes for the recovery of microbial carotenoids. Nevertheless, the current employment of these solvents for recovery of carotenoids is restricted to scientific exploration, as their feasibility for practical application in industrial settings has yet to be conclusively demonstrated. KEY POINTS: • ILs and DES share many tailoring properties for the recovery of microbial carotenoids • The use of ILs and DES for microbial carotenoid extraction remains driven by scientific curiosity. • The economic feasibility of ILs and DES is yet to be demonstrated in industrial applications.

Enhanced Z-Isomerization of Astaxanthin in Paracoccus carotinifaciens via Microwave Drying

The effects of microwave drying conditions of a Paracoccus carotinifaciens culture solution on astaxanthin Z-isomerization and degradation were investigated. The microwave drying significantly increase the ratio of astaxanthin Z-isomers, and the higher the microwave power and the longer the drying time, the higher the total Z-isomer ratio of astaxanthin, but such conditions also accelerated astaxanthin degradation. We found that the addition of powdered oils enhanced the Z-isomerization reaction. For example, when the P. carotinifaciens culture solution was dried at 1000 W power for 5 min without and with powdered rapeseed oil, total Z-isomer ratios of astaxanthin in resulting dried powder were 14.9 and 47.4%, respectively. Furthermore, the storage test of the dried P. carotinifaciens powder showed that astaxanthin Z- isomers were stable at 4℃ in a low-oxygen atmosphere. As astaxanthin Z-isomers have greater bioavailability and potentially exhibit superior biological activities than the all-E-isomer, the dried P. carotinifaciens powder obtained by the method of this study is expected to be used as a value-added astaxanthin source.

Improved Flesh Pigmentation of Rainbow Trout (Oncorhynchus mykiss) by Feeding Z-Isomer-Rich Astaxanthin Derived from Natural Origin

The use of Paracoccus carotinifaciens-derived natural astaxanthin as an alternative to synthetic astaxanthin has attracted considerable attention from the aquaculture industry. Furthermore, to enhance the bioavailability of astaxanthin, its "Z-isomerization" has been actively studied in recent years. This study investigated the effects of feeding a diet containing astaxanthin rich in the all-E- or Z-isomers derived from P. carotinifaciens on the pigmentation and astaxanthin concentration in rainbow trout (Oncorhynchus mykiss) flesh. Z-Isomer-rich astaxanthin was prepared from the P. carotinifaciens-derived all-E-isomer by thermal treatment in fish oil, and the prepared all-E-isomer-rich astaxanthin diet (E-AST-D; total Z-isomerratio = 9.1%) and Z-isomer-rich astaxanthin diet (Z-AST-D; total Z-isomer ratio of astaxanthin = 56.6%) were fed to rainbow trout for 8 weeks. The feeding of Z-AST-D resulted in greater pigmentation and astaxanthin accumulation efficiency in the flesh than those fed E-AST-D. Specifically, when E-AST-D was fed to rainbow trout, the SalmoFan score and astaxanthin concentration of the flesh were 22.1±1.4 and 1.36±0.71 μg/g wet weight, respectively, whereas when Z-AST-D was fed, their values were 26.0±2.5 and 5.33±1.82 μg/g wet weight, respectively. These results suggest that P. carotinifaciens-derived astaxanthin Z- isomers prepared by thermal isomerization are more bioavailable to rainbow trout than the all-E-isomer.

Astaxanthin production using Paracoccus carotinifaciens: a way forward?

Paracoccus carotinifaciens could be considered a key microbial factory for obtaining healthier natural products such as astaxanthin (AXT), thus contributing to a bioeconomy. Short cultivation time, high production titers, and thin cell wall are the main advantages that make this bacterium promising in the development of sustainable third-generation biorefineries.

More Than Pigments: The Potential of Astaxanthin and Bacterioruberin-Based Nanomedicines

Carotenoids are natural products regulated by the food sector, currently used as feed dyes and as antioxidants in dietary supplements and composing functional foods for human consumption. Of the nearly one thousand carotenoids described to date, only retinoids, derived from beta carotene, have the status of a drug and are regulated by the pharmaceutical sector. In this review, we address a novel field: the transformation of xanthophylls, particularly the highly marketed astaxanthin and the practically unknown bacterioruberin, in therapeutic agents by altering their pharmacokinetics, biodistribution, and pharmacodynamics through their formulation as nanomedicines. The antioxidant activity of xanthophylls is mediated by routes different from those of the classical oral anti-inflammatory drugs such as corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs): remarkably, xanthophylls lack therapeutic activity but also lack toxicity. Formulated as nanomedicines, xanthophylls gain therapeutic activity by mechanisms other than increased bioavailability. Loaded into ad hoc tailored nanoparticles to protect their structure throughout storage and during gastrointestinal transit or skin penetration, xanthophylls can be targeted and delivered to selected inflamed cell groups, achieving a massive intracellular concentration after endocytosis of small doses of formulation. Most first reports showing the activities of oral and topical anti-inflammatory xanthophyll-based nanomedicines against chronic diseases such as inflammatory bowel disease, psoriasis, atopic dermatitis, and dry eye disease emerged between 2020 and 2023. Here we discuss in detail their preclinical performance, mostly targeted vesicular and polymeric nanoparticles, on cellular models and in vivo. The results, although preliminary, are auspicious enough to speculate upon their potential use for oral or topical administration in the treatment of chronic inflammatory diseases.

Natural Pigments Production and Their Application in Food, Health and Other Industries

In addition to fulfilling their function of giving color, many natural pigments are known as interesting bioactive compounds with potential health benefits. These compounds have various applications. In recent times, in the food industry, there has been a spread of natural pigment application in many fields, such as pharmacology and toxicology, in the textile and printing industry and in the dairy and fish industry, with almost all major natural pigment classes being used in at least one sector of the food industry. In this scenario, the cost-effective benefits for the industry will be welcome, but they will be obscured by the benefits for people. Obtaining easily usable, non-toxic, eco-sustainable, cheap and biodegradable pigments represents the future in which researchers should invest.