Carotenoid Yeasts and Their Application Potential.

Carotenoids are part of a diverse group of isoprenoid compounds. Due to the many properties they possess, they may become an alternative to synthetic additives in various industrial sectors. The increase in consumer demand and awareness determines research into extracting them from plants, algae and microorganisms. The extraction of carotenoids from plants is an inefficient method and generates additional production costs. On the other hand, the carotenoid potential of microorganisms, especially among yeasts, has not been fully exploited. The diversity of yeast species and strains influences the extraction of many fractions of carotenoids, including the less known ones such as thorulene and tholuradine. The developed adaptability of yeast enables the optimisation of their culture, which facilitates the understanding of their metabolic pathways. At the same time, the coordination of carotenoid and lipid synthesis may prevent their degradation or the loss of their bioactive properties. Application research has been conducted mainly in the feed industry, where their colouring and antimicrobial or immunomodulating properties are used. In the medical and pharmaceutical fields, there is not much research due to safety restrictions and the necessity of the high purity of the fractions. This review also highlights the overlooked aspect of carotenoids' biodegradability, which is required to exploit the bioactive properties of microbial carotenoids.