Microbial Pigments for Food Coloring and Textile Dyeing: a Review

Abstract

At present, demand for natural sources of coloring substances is increasing as a result of increasing consumer’s awareness for the healthy safety of chemically synthesized pigments used in different sectors. These natural coloring substances has been obtained from plants (fruits, vegetables, roots, and flowers); animals such as scale insects and microorganisms. Extraction of natural colors from plants have many disadvantages including limited supply in the season of bad climatic conditions, batch to batch variation and instability under some environmental conditions. However, from all sources of natural pigments, microorganisms are having great potential, since the productivity will be increased by fermentation process development and the microorganisms are amendable to genetic engineering. Different group of microorganisms (bacteria, yeasts, fungi and micro algae) have been observed to produce different pigments with different chemical structures which are having different application. These pigment molecules include: carotenoids, melanin, flavins, quinines, prodigiosin and more specifically monascin, violacein, or indigo. These microbial pigments are having application in the field of pharmaceutical, cosmetics, food/feed, textile, agriculture and farming. Prodigiosin, violacein and some carotenoids have also receiving increasing interests since these microbial metabolites have valuable application as immunomodulating, anticancer and bioactive molecules. The rest of the carotenoids and fungal polyketides are valuable microbial metabolite used as food/feed additives or food coloring agents. In Ethiopia, very few literatures are available on microbial pigment production and application as food colorant and textile dyeing. In order to isolate and characterize pigment producing microorganisms from a local habitat and formulation of pigments for utilization, information about the pigment producing microorganisms is required. Therefore, this paper reviews microbial sources of pigments and their uses in food/feed and textile dyeing.