Microbe-Mediated Degradation of Synthetic Dyes in Wastewater - Microbial Degradation of Synthetic Dyes in Wastewaters - page 224

3.2 In uence of Carbon and Nitrogen Sources

in the Decoloration Process

Carbon and nitrogen sources have an important in uence on the extent of decol-

oration using microorganisms. Different microbial metabolic characteristics cause
to differential uptake of C and N sources, thus affecting azo dye decoloration. As
dyes are de cient in carbon, biodegradation without an extra carbon source is very

dif et al. 2009 ; Tony et al. 2009 ; Levin et al. 2010 ).

Carbon sources serve two purposes: as a source of carbon and energy for the growth
and survival of the microorganisms and also as an electron donor, which is nec-
essary for the breakage of the azo bond (Perumal et al. 2007 ; Gonzalez-Gonzalez-
Gutierrez and Escamilla-Silva 2009 ; Yang et al. 2009 ; Yemendzhiev et al. 2009 ). In
several cases,

cult (Asgher et al. 2009 ; Kheli

uents was
increased in the presence of glucose. In other cases, the presence of several carbon
sources is necessary, as in the case of Staphylococcus arlettae which causes >90 %
decoloration of Reactive Yellow 107 and Reactive Red in the presence of glucose
and yeast extract, <50 % in the absence of yeast extract and no decoloration when
yeast extract and glucose are substituted with sodium pyruvate (Elisangela et al.
2009 ). Starch is another common source of carbon that is frequently used as an
additive in the textile

the microbial decoloration of azo dyes or textile ef

nishing process. Therefore, the use of microorganisms, that
can use starch as a co-substrate, would be bene cial for the treatment of wastewater

from the textile industry (Babu et al. 2007 ). Furthermore, glucose also inhibits the
discoloration rate of Golden Yellow by a consortium of G. geotrichum and B.
laterosporus (Waghmode et al. 2011 ). In addition to the type of the carbon source,
it is also important to consider the amount of the source which must be suf

cient to
meet microbial growth requirements and achieve decoloration. However, high
carbon concentrations can also lead to low decoloration, because the microorgan-
isms utilize the carbon source preferentially to the dye (Waghmode et al. 2011 ;
Kumar et al. 2012 ). Additionally, the concentration must be suf ciently low to limit

the growth of the biomass and allow metabolic activity without enhancing the
biosorption process (Khouni et al. 2012 ). The goal for microorganisms is to use the
dye as a carbon source or even as the sole source of carbon and nitrogen. This goal
can be achieved in some cases, if the microorganisms are acclimatized by suc-
cessively increasing the amount of dye and diminishing the carbon source until they
can survive with the azo dye alone. Examples are the growth of Saccharomyces
cerevisiae (Jadhav et al. 2007 ) and Sphingomonas paucimobilis (Ayed et al. 2011 )
with Methyl Red; Pseudomonas, Arthrobacter and Rhizobium consortium with
Acid Orange 7 (Ruiz-Arias et al. 2010 ); Pleurotus sanguineus with Drimaren
Brilliant Blue (Machado et al. 2006 ); Aspergillus fumigatus with a mixture of
Reactive Black RC, Reactive Yellow HF2-GL, Reactive Blue BGFN, Reactive
Black B-150 and Reactive Red A-6BF (Jin et al. 2007 ); Micrococcus glutamicus
with Navy Blue HE2R and its reaction intermediates (Saratale et al. 2009 ); Willi-
opsis saturnus, Candida sp. and Trichosporon porosum with Yellow 4R-HE, Black
B V, Blue RR-BB and Red 7B-HE (Martorell et al. 2012 ), A. niger with Direct

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