Biotransformation of Food Dyes by Human Intestinal Bacteria (Streptococcus faecalis, Eschericia coli)

Biotransformation of food dyes (Tartrazine and Quinoline yellow) by Streptococcus faecalis and Escherichia coli isolated from human intestinal microflora was investigated. Decolourisation of the media containing the dyes was used as an index of biotransformation. Biotransformation was higher under aerobic than under anaerobic conditions. The results obtained were attributed to the organisms cytosolic flavin-dependent reductases and redox equivalents generated by metabolism of soluble starch which transfer electrons to the chromophoric group of the dyes. The potential health risk of the resulting colourless metabolites (aromatic amines) is under investigation.