Bacterial Degradation of Azo Dye Containing Wastes - Microbial Degradation of Synthetic Dyes in Wastewaters - page 77

(Solis et al. 2012 ). Less toxicity of metabolites was reported by many researchers
using above mentioned methods which indicates detoxi cation of azo dyes by

bacterial activity.

10 Patents on Biological Azo Dyes Treatment

Several independent research groups have been working worldwide on biological
treatment of azo dyes containing waste and they also patented their researches. US
patent number 5,618,726 has been issued in 1997 on subject of biodegradable azo
dyes (Paszczynski et al. 1997 ). In this patent, Acid Yellow 9 and other two syn-
thesized azo dyes were mineralized by twelve Streptomyces species and white rot
fungus Phanerochaete chrysosporium was reported. In 2009, biological treatment
of acidic azo dye wastewater in bioreactors has been patented with Indian patent
number 230896 (Sharma and Sharma 2009 ). In this patent, researchers have used
consortium developed from activated sludge for reduction of BOD, color and COD
of wastewater. They designed up

ow reactors and developed bio lms on grits.

They con rmed their results of degradation by UV-Vis spectroscopy, GC-MS

analysis and also studied detoxi shes

and plants. Other US patents, such as number US 5,091,089, US 6,613,559 B2, US
4,655,926 and US 4,554,075, have been reported for the biological treatment of dye
containing wastewater (Blanquez et al. 2008 ).

cation of dye containing wastewater using

11 Future Perspectives

Global environmental pollution is a major threat now-a-days. Therefore, govern-
ment legislations in all developed countries are becoming more stringent for
environment protection. Water pollution, resulted from synthetic chemicals dis-
charge from industries,

is a big environmental issue, especially untreated dye

containing ef uent. Textile and dye stuff manufacturing industries have a great

challenge to treat a large volume of dye ef uent and recycle it which increases the

cost of waste management. Till date, there is no attractive biological method
available to be directly applied on a commercial scale to degrade and detoxify dye
ef

eld using bacteria with objectives, such
as use of acclimatized consortia rather than pure culture and reactor scale study in
non-sterile conditions with actual dye ef

uent. Still there is a need to work in this

uent in contrast to pure dye decolorization

study at ask level. There is also interesting alternative to use MFCs to treat

wastewater along with generation of valuable products. Applications of molecular
biology are also useful to study diversity of bacteria present in consortia and also
identify genes encoding enzymes responsible for azo dye degradation. With the
help of genetic engineering, genetically modi

ed bacteria strains are created by
transferring genes and recombinant strains with higher ef ciency to degrade azo dye