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Modification of azo dyes by lactic acid bacteria
I M Pérez-Díaz1, R F McFeeters
1USDA-ARS, SAA Food Science Research Unit, North Carolina State University, Raleigh, NC 27695-7624, USA. ilenys.pérez-díaz@ars.usda.gov
Journal of Applied Microbiology
|March 24, 2009
Summary
Lactic acid bacteria (LAB) can anabolize (build up) azo dyes like tartrazine, but only in anaerobic environments. This study highlights LAB’s unique capability to modify food and textile dyes.
Area of Science:
- Microbiology
- Biotechnology
- Food Science
Background:
- Lactic acid bacteria (LAB) are known food-related microorganisms.
- Previous studies documented Lactobacillus casei and Lactobacillus paracasei modifying the azo dye tartrazine.
- Azo dyes are widely used in the textile industry and can be environmental pollutants.
Purpose of the Study:
- To screen various lactic acid bacteria (LAB) for their ability to modify tartrazine and other azo dyes.
- To investigate the conditions under which LAB modify azo dyes.
- To characterize the product of azo dye modification by LAB.
Main Methods:
- Screening of fourteen lactic acid bacteria (LAB) strains.
- Culturing LAB in modified chemically defined media under anaerobic and aerobic conditions.
- Analysis of tartrazine modification using liquid chromatography-mass spectrometry.
Main Results:
- Most LAB strains modified tartrazine under anaerobic conditions but not aerobic conditions.
- Microbial growth was not inhibited by the presence of azo dyes.
- The modification product was identified as a molecule 111 daltons larger than tartrazine, exhibiting distinct color and spectral properties under different oxygen conditions.
Conclusions:
- LAB can anabolize azo dyes exclusively under anaerobic conditions.
- This study is the first to report the anabolism of azo dyes by food-related microorganisms like LAB.
- LAB represent a novel biological tool for azo dye modification in food and potentially industrial applications.
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