<span style="font-size: 20.0pt;mso-bidi-font-size:14.0pt;font-family:"Times New Roman","serif"; color:black">Biodegradation of benzidine based azodyes Direct red and Direct blue by the immobilized cells of <i><span style="font-size:20.5pt; mso-bidi-font-size:14.5pt;font-family:"Times New Roman","serif";color:black">Pseudomonas fluorescens </span></i><span style="font-size:20.0pt;mso-bidi-font-size:14.0pt; font-family:"Times New Roman","serif";color:black">D41 </span></span>

1131-1136<span style="font-size: 14.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";="" color:black"="">Benzidine based azodyes are proven carcinogens, mutagens and have been linked to bladder cancer of human beings and laboratory animals. The textile and dyestuff manufacturing industry are the two major sources that released azodyes in their effluents. The dye, Direct blue contains two carcinogenic compounds namely benzidine (BZ), 4-amino biphenyl (4- ABP), while the dye Direct red has benzidine (BZ). Among 40 isolates of Pseudomonas fluorescens <span style="font-size:14.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";color:black"="">screened, one isolate designated as D41<span style="font-size:12.0pt;mso-bidi-font-size: 6.0pt;font-family:HiddenHorzOCR;mso-hansi-font-family:" times="" new="" roman";="" mso-bidi-font-family:hiddenhorzocr;color:black"=""> <span style="font-size: 14.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";="" color:black"="">was found to be capable of  extensively degrading the dyes Direct blue and Direct red. Immobilized cells of <span style="font-size:14.5pt;mso-bidi-font-size:8.5pt; font-family:" times="" new="" roman","serif";color:black"="">P. fluorescens D41 efficiently degraded Direct red (82%) and Direct blue (71 %) in the presence of glucose. </span

Toxicity assessment and microbial degradation of azo dyes

618-626Toxic effluents containing azo dyes are discharged from various industries and they adversely affect water resources, soil fertility, aquatic organisms and ecosystem integrity. They pose toxicity (lethal effect, genotoxicity, mutagenicity and carcinogenicity) to aquatic organisms (fish, algae, bacteria, etc.) as well as animals. They are not readily degradable under natural conditions and are typically not removed from waste water by conventional waste water treatment systems. Benzidine based dyes have long been recognized as a human urinary bladder carcinogen and tumorigenic in a variety of laboratory animals. Several microorganisms have been found to decolourize, transform and even to completely mineralize azo dyes. A mixed culture of two Pseudomonas strains efficiently degraded mixture of 3-chlorobenzoate (3-CBA) and phenol/cresols. Azoreductases of different microorganisms are useful for the development of biodegradation systems as they catalyze reductive cleavage of azo groups (-N=N-) under mild conditions. In this review, toxic impacts of dyeing factory effluents on plants, fishes, and environment, and plausible bioremediation strategies for removal of azo dyes have been discusse