Degradation of Anthroquinone Dyes Stimulated by Fungi - Microbial Degradation of Synthetic Dyes in Wastewaters - page 343

Radha et al. ( 2005 ) studied the effect of temperature on fungal growth of P.
chrysosporium and the decolorization process. Different temperatures were selected
ranging from 20

C for decolorization of dyes. It was observed that thedecol-
orizing activity of fungi was reduced at both higher and lower temperature, indi-
cating the lack of peroxidase production which is generally required for the
decolorization of dyes or the enzyme gets denatured at higher (>35

45 °

-

° C) or lower

(<35 C was

found most suitable for the fungal growth as well as decolorization process.
The effect of temperature on decolorization of RBBR was also studied by Yang
et al. ( 2009 ) and it was observed that the variation in temperature had minimum
effect on decolorization of RBBR below 70

° C) temperature. Hence, for P. chrysoporium, a temperature of 35 °

° C and maximum decolorization was

attained at 50 60 ° C by a white-rot fungus, Trametes sp. strain SQ01 after 10 min

-

of incubation.

5.7 Agitation and Aeration

Since most of the ligninolytic fungi are obligate aerobes, they essentially, require
oxygen for the maintenance of their viability. There is a need for oxygen for multi-
purpose in fungi i.e., lignin degradation also requires oxygen, either for the mycelial
generation of H 2 O 2 for peroxidases or for the direct action of oxidases. Oxygen can
also degrade lignin fragments directly. Hence, the demand for oxygen generally
depends on the fungus and its ligninolytic system. The water solubility of oxygen is
very low i.e. 8 mg l − 1 at 20 C. As the oxygen supply to the culture media is necessary

for cultivation, its solubility can be enhanced by both aeration and agitation.

°

5.8 Initial Dye Concentration

For the removal of dyes, it is important to optimize the initial dye concentration.
Dyes are usually toxic to microorganisms and its toxicity depends on the type of
dye. Higher concentrations of dyes are invariably toxic. The range of initial dye
concentration studied generally varies from 50 1,000 mg l − 1 , and also depends on

-

microorganism and type of dye (Singh 2006 ).

6 Conclusion

A lot of studies have been carried out on fungal decolorization of chemical dyes on
a laboratory scale to nd the potential fungal strains with effective enzymes. The

management of textile industrial ef

uents is no doubt a complicated task, taking
into consideration the complexity of the waste compounds present in the waste