Microbial carotenoids as bioactive food ingredients

Nature is rich in colors (minerals, plants, microalgae, etc) and pigment-producing microorganisms (fungi, yeasts, bacteria) are quite common. Among the molecules produced by microorganisms are carotenoids, melanins, flavins, phenazines, quinones, bacteriochlorophylls and more specifically monascins, violacein or indigo. The food industry was mainly using synthetic colors up to the nineties, 1995 being the beginning of the switch to natural colorants, conversion accelerated by the Southampton study of 2007 which linked some synthetic food colors with hyperactivity of childrens. The natural food coloring industry market is now growing at 10%-15% annually. Among food pigments, carotenoids are of special interest as they are bioactives with antioxidant, anticancer, vitamin, or hormone properties. Growing interest in healthy diets and an aging global population is anticipated to fuel growth in the global carotenoids market which is intended to reach USD 1.2 billion by 2015. More than 650 different carotenoids are produced by plants, algae, bacteria, and fungi. At present time, only a few can be obtained at a large scale and microbial fermentation is among the most promising tools to achieve the production of large amounts of new carotenoids. Examples presented in this review are b-carotene, lycopene, astaxanthin, zeaxanthin, canthaxanthin, torulene, isorenieratene and dihydroxyisorenieratene… Applications are numerous in health supplements, animal feed, nutraceutics, food colorants. Last part concludes with some prospects for carotenoid production by genetically modified microorganisms, especially directed evolution and combinatorial biosynthesis.