Bacterial pigments and their applications

Natural pigments sourced from ores, insects, plants and animals were the colorants used since prehistoric period. Synthetic dyes which took the place of natural pigments in the middle of 19th century still rule the field to the maximum extent in spite of its hazardous effect to humans, animals and environment. As an alternative to synthetic pigments, bacterial pigments due to their better biodegradability and higher compatibility with the environment, offer promising avenues for various applications. The industry is now able to produce some bacterial pigments for applications in food, pharmaceuticals, cosmetics and textiles. Extraction of bacterial pigments in relatively pure and concentrated forms is the main technological challenge. Optimization of fermentation process and the medium components are reported as key strategies for economic recovery of pigments. Research work needs to be carried out to formulate the fermentation media for each bacterial pigment on large scale by using economical and easily available sources for commercial process. Recent advances in synthetic biology, metabolic engineering efforts of bacteria will greatly expand the pigments that could be produced economically in sufficient amounts for industrial application. This review summarizes the current technology status and challenges, economics, novel strategies for production of bacterial pigments and metabolic engineering of bacteria with a focus on applications of bacterial pigments in food industry, pharmaceutical industry, dyeing as well as on other applications.