الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
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Abstract
Azo dyes are orgahic pollutants released into the environment as effluents from dyestuffs and textile printing industries. They are toxic and carcinogenic and cause extensive coloration when released into the environment. Recent studies demonstrated the possible use of microbial communities for the remediation of dye containing wastewater. The main goal of the present work focused on isolating bacterial strains capable of decolorizing azo dye solutions. Two approaches were investigated; the first is the decoloration of methyl red through a degradative mechanism and the second is the decoloration of fast blue by biosorption. The results and conclusions are summarized as follows:
1- Eleven MR degrading bacterial strains was isolated. Seven endospore forming bacterial phenotypes were chosen and identified using 16 S rRNA. The strains coded N1, N4, and N40 were 100% identical with respect to their 16S rRNA sequences suggesting that these isolates are phylogenetically closely related . Isolates N2, N3 and N9 showed a unique nucleotide sequence. The 16S rRNA sequences of isolate N10 were 99.8% similar to B. subtilis reference strain 168.The 16S rRNA phylogenetic tree proved also that N1, N4 and N40 were clustered with a B. pumilus reference strain. Phenotypic characterization of these two bacterial strains B. pumilus N40 and 8. subtilis N10 was investigated and confirmed their identification.
2- In order to select the bacterium that shows maximal decolorization of MR from a culture medium, a screening experiment was performed. The two strains, B. pumilus N40 and B. subtilis N10 showed maximum MR decolorization percentages (95.3 and 94.1, respectively) with relatively high biomass formation results after 6 hours of shaking.