Toxicological effect of indole and its azo dye derivatives on some microorganisms under aerobic conditions

Azo dyes are ubiquitous commercial chemicals that present unique environmental problems. The azo dyes in particular can undergo natural anaerobic degradation to potentially carcinogenic amines. They pose a major problem for water-treatment plants downstream. One strategy to remidate polluted surface contaminants is to make use of the degradative capacity of bacteria rather than using destructive chemical reactions. Therefore, pathogenic and non-pathogenic microorganisms namely; Bacillus thuringiensis, Bacillus subtilis, Bacillus megaterium, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Saccharomyces cerevisiae have been chosen and the toxicological effect of indole and its azo dye methyl derivatives on these microorganisms was studied under aerobic conditions. While these compounds have showed remarkable activity against B. megaterium, B. subtilis, B. thuringiensis and S. aureus, they did not exhibit any activity against P. vulgaris. However, indole acted as an inhibitor on all of these compounds specially the Gram negative bacterium P. aeruginosa.