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Degradation of Synthetic Aromatic Textile Dyes by Native Bacteria Isolated from Textile Mill sites

By ayman on June 08,2008

Osama M. Darwesh, Wafaa M. Abd El-Rahim, Olfat S. Barakat, Mohamed Z. Sedik, and Hassan Moawad


Hundred fifty bacterial isolates were obtained by enrichment culture from 12 samples collected from soil contaminated with dye effluents and effluent treatment plants of textile and dyeing industry at New Borg El-Arab, Cairo, Kafr El-Dawar, and El-Mehalla El-Kubra regions. The isolation of the microbial consortium was conducted on mineral salts medium (MSM) supplemented with three dyes. The microbial consortium was able to decolorize dyes, as evident by clearing the three azo dyes solutions under anoxic and anaerobic conditions. The isolates were checked for their ability to decolorize direct violet and reactive red dyes. The efficiency of the bacterial isolates in dye removal was investigated under aerobic and anaerobic conditions. The study revealed that no decolorization has taken place by isolates under aerobic conditions. The results revealed that the percentage of decolorization by the isolates reached 98.52 and 97.95 % of the original color of direct violet and reactive red dyes after 9 and 15 days, respectively, under anaerobic conditions. Twenty five isolates were selected as representative isolates based on the morphological and biochemical analyses. Two isolates are long rod, 6 isolates are short rods, and seventeen isolates belong to family enterobacteraece. The characterization of bacteria showed that the isolates belong to Bacillus and Pseudomonas sp. The degradation of the dyes is usually judged by the formation of aromatic amines. Most of the isolates under anoxic conditions were found to produce aromatic amines. This suggests the degradation of the dyes by the isolated bacteria.

Keywords: degradation, textile dyes removal, bioremediation, bacteria

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