Carotenoids are a large group of health-promoting compounds used in many industrial sectors, such as foods, feeds, pharmaceuticals, cosmetics, nutraceuticals, and colorants. Considering the global population growth and environmental challenges, it is essential to find new sustainable sources of carotenoids beyond those obtained from agriculture. This review focuses on the potential use of marine archaea, bacteria, algae, and yeast as biological factories of carotenoids. A wide variety of carotenoids, including novel ones, were identified in these organisms. The role of carotenoids in marine organisms and their potential health-promoting actions have also been discussed. Marine organisms have a great capacity to synthesize a wide variety of carotenoids, which can be obtained in a renewable manner without depleting natural resources. Thus, it is concluded that they represent a key sustainable source of carotenoids that could help Europe achieve its Green Deal and Recovery Plan. Additionally, the lack of standards, clinical studies, and toxicity analysis reduces the use of marine organisms as sources of traditional and novel carotenoids. Therefore, further research on the processing of marine organisms, the biosynthetic pathways, extraction procedures, and examination of their content is needed to increase carotenoid productivity, document their safety, and decrease costs for their industrial implementation.

In recent years, there has been an increasing concern related to the contamination of aqueous ecosystems by heavy metals, highlighting the need to improve the current techniques for remediation. This work intends to address the problem of removing heavy metals from waterbodies by combining two complementary methodologies: adsorption to a copolymer synthesized by inverse vulcanization of sulfur and vegetable oils and phytoremediation by the microalga Chlorella sorokiniana to enhance the metal adsorption. After studying the tolerance and growth of Chlorella sorokiniana in the presence of the copolymer, the adsorption of highly concentrated Cd²⁺ (50 mg L^-1) by the copolymer and microalgae on their own and the combined immobilized system (AlgaPol) was compared. Additionally, adsorption studies have been performed on mixtures of the heavy metals Cd²⁺ and Cu²⁺ at a concentration of 8 mg L^-1 each. AlgaPol biofilm is able to remove these metals from the growth medium by more than 90%. The excellent metal adsorption capacity of this biofilm can be kinetically described by a pseudo-second-order model.

Development of a sustainable, low-cost sorbent, which highly efficiently removes heavy metals from complex mixtures and is reusable.

The identification of new functional food constituents is a priority to improve the prognosis and prevention of colorectal cancer (CRC). In this study, several bacterial and algal phytoene-enriched extracts were obtained, and their potential activity against oxidative damage and their ability to inhibit proliferation and cell migration in several human colon-adenocarcinoma-derived cell lines were assessed. The main conclusions indicate that total extracts of Sphingomonas echinoides and Chlorella sorokiniana exhibited the highest protective effect against oxidative damage. All extracts enhanced the activity of detoxifying enzymes, particularly importantly the increase of NAD(P)H:quinone oxidoreductase activity, which reached a value 40% higher than that of untreated control cells upon exposure to Escherichia coli extracts. Staphylococcus haemolyticus and transgenic E. coli extracts significantly arrested the migration capacity of both cell lines, while S. haemolyticus and C. sorokiniana extracts inhibited cell proliferation by 15 to 20% compared to untreated cells. These results point to these extracts as potential antioxidant complements able to protect cells against oxidative damage and with a moderate ability to inhibit the proliferation and migration of CRC tumor cells, paving the way to design functional foods or probiotic formulations with preventive properties against oxidative stress-related diseases, such as cancer, or as starting point for purifying anticancer compounds.

Phenol-derived compounds are among the most hazardous organic pollutants for aquatic environments due to their relatively high aqueous solubility. Microalgae harbor metabolic pathways that enable the degradation of phenolic compounds into less toxic derivatives, highlighting their potential for the bioremediation of these contaminants. In this study, four microalgal species were evaluated for their tolerance and biodegradation capacity of a mixture of phenolic compounds which include phenol, p-cresol, and acetophenone. The results revealed that Chlorella sorokiniana and Nannochloropsis gaditana could tolerate higher concentrations of the mixture (60, 50, and 25 mg L⁻¹ of phenol, p-cresol, and acetophenone) than Chlamydomonas reinhardtii and Tetraselmis chuii (60, 30, and 20 mg L⁻¹ of phenol, p-cresol, and acetophenone). Notably, Tetraselmis chuii could biodegrade these compounds with the highest efficiency (32, 45, and 85% of initial phenol, p-cresol, and acetophenone, respectively) after 72 h of cultivation. In the absence of alternative carbon sources in the medium, Tetraselmis chuii also biodegraded 45, 60, and 51% of initial phenol, p-cresol, and acetophenone, at 72 h, highlighting its potential for bioremediation processes. Finally, the ascorbate peroxidase, catalase, and phenol hydroxylase enzymatic activities of Tetraselmis chuii were studied in presence of the pollutants, showing increasing activity levels of these enzymes (123, 135, and 173% of control cultures for APX, CAT, and PH, respectively) involved in the antioxidant system and the degradation of phenolic compounds.