Bacterial Degradation of Azo Dye Containing Wastes - Microbial Degradation of Synthetic Dyes in Wastewaters - page 60

Table 3 Degradation azo dyes by mixed cultures and consortia
Consortium Bacterial strains Azo dye References

Consortium
TJ-1

Aermonas caviae, Proteus
mirabilis and Rhodococcus
globerulus

Acid Orange 7 Joshi et al.

( 2008 )

Consortium
JW-2

Paenibacillus polymyxa,
Micrococcus luteus and
Micrococcus sp.

Reactive
Violet 5R

Moosvi
et al. ( 2007 )

A consortium
of ve bacteria

Alcaligenes faecalis,
Sphingomonas sp. EBD,
B. subtilis, B. thuringiensis
and Enterobacter ancerogenus

Direct Blue-15 Kumar

et al. ( 2007 )

Consortium-GR P. vulgaris and Micrococcus

glutamicus

Scarlet R and
mixture of 8 dyes

Saratale
et al. ( 2009 )

under aerobic conditions and Klebsiella sp., Escherichia sp., Bacillus sp. and
Clostridium sp. as dominant species under anaerobic conditions (Saratale et al.
2011 ). A consortium consisting of Aeromonas caviae, P. mirabilis and Rhodo-
coccus globerulus was tested against 16 azo dyes individually and also a mixture
(200 mg l − 1 ) and found to decolorize these dyes ef

ciently (Joshi et al. 2008 ;
Saratale et al. 2011 ). A few examples of mixed culture and consortium reported in
the literature are shown in Table 3 .
The enzymatic activity of a single strain is highly in uenced by the presence of

other microorganisms, and the biocatalytic activity of a consortium is different than
from its individual constituents. Microorganisms, in a consortium, work synergis-
tically to enhance the decolorization activity. Jadhav et al. ( 2010 ) have also reported
ef

uent decolorization by a consortium than the individual strains.
Consortium is found to increase rate and percentage of azo dye decolorization,
decrease time for decolorization and better mineralization of azo dyes as compared
to single strain. However, it is well known that enzymatic activity and enzymatic
induction in consortium are not the sum of the respective enzymatic activities and
induction of the individual strains (Solis et al. 2012 ).
In the preparation of consortia,

cient dye ef

the proportion of each microorganism is

important to obtain an ef cient system for the treatment of azo dyes. Khehra et al.

( 2005 ) described that an equal proportion of all four isolates of consortium
increased 3-fold ef ciency of dye decolorization as compared to other combinations

of the same isolates. Forss and Welander ( 2011 ) reported that decolorization of
Reactive Black 5 and Reactive Red 2 was more ef

cient with a 2:3 proportion of

Bjerkandera sp. and native micro ora than with a 2:4 proportion. Thus, a pro-

portion of culture in consortia also varies from process to process depending on the
number of consortia and nature of dye ef uent.

cient decolorization of azo dyes by consortium also depends on a combi-
nation of aerobic and anaerobic process. Literatures are available on sequential
decolorization of azo dyes by the consortium, in which during microaerophilic
condition, azo dyes were partially degraded and produced some intermediates and

Ef