Modification of azo dyes by lactic acid bacteria
Article first published online: 18 MAR 2009
© 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 107, Issue 2, pages 584–589, August 2009
How to Cite
Pérez-Díaz, I.M. and McFeeters, R.F. (2009), Modification of azo dyes by lactic acid bacteria. Journal of Applied Microbiology, 107: 584–589. doi: 10.1111/j.1365-2672.2009.04227.x
- Issue published online: 9 JUL 2009
- Article first published online: 18 MAR 2009
- 2008/1739: received 10 October 2008, revised 11 December 2008 and accepted 30 December 2008
- azo dyes;
- food dyes;
- lactic acid bacteria;
- tartrazine anabolism;
- textile waste waters
Aim: The ability of Lactobacillus casei and Lactobacillus paracasei to modify the azo dye, tartrazine, was recently documented as the result of the investigation on red coloured spoilage in acidified cucumbers. Fourteen other lactic acid bacteria (LAB) were screened for their capability to modify the food colouring tartrazine and other azo dyes of relevance for the textile industry.
Methods and Results: Most LAB modified tartrazine under anaerobic conditions, but not under aerobic conditions in modified chemically defined media. Microbial growth was not affected by the presence of the azo dyes in the culture medium. The product of the tartrazine modification by LAB was identified as a molecule 111 daltons larger than its precursor by liquid chromatography-mass spectrometry. This product had a purple colour under aerobic conditions and was colourless under anaerobic conditions. It absorbed light at 361 and 553 nm.
Conclusion: LAB are capable of anabolizing azo dyes only under anaerobic conditions.
Impact and Significance of the Study: Although micro-organisms capable of reducing the azo bond on multiple dyes have been known for decades, this is the first report of anabolism of azo dyes by food related micro-organisms, such as LAB.