A New Era for Using Natural Pigments: The Case of the C ₅₀ Carotenoid Called Bacterioruberin

Haloarchaea are extremophilic microorganisms belonging to the Archaea domain that require high salt concentrations to live, thus inhabiting ecosystems like salty ponds, salty marshes, or extremely salty lagoons. They are more abundant and widely distributed worldwide than initially expected. Most of them are grouped into two families: Halobacteriaceae and Haloferacaceae. The extreme conditions under which haloarchaea survive contribute to their metabolic and molecular adaptations that make them good candidates for the design of bioremediation strategies or the use of the cells as cellular factories to produce highly marketable molecules: enzymes, bioplastics, antibiotics, and natural pigments. Within the molecular adaptations of these microorganisms, the production of rare C₅₀ carotenoids like the one called "bacterioruberin" is attracting attention worldwide, due to their biological activities, including antioxidant, antitumoral, immunomodulatory, antilipidemic, and antiglycemic effects. The production of this natural carotenoid contributes to meeting the high demand that the global carotenoid market is experiencing, to replace the use of chemically synthesized pigments with natural colorants/antioxidants. In this work, new advances in the production of these natural carotenoids are described, placing special emphasis on the challenges of their production on a large scale, as well as on their promising applications in cosmetics, pharmaceuticals and food.