Microbial Degradation of Basic Dyes in Wastewaters - Microbial Degradation of Synthetic Dyes in Wastewaters - page 89

3 Factors Effecting Dye Degradation Process

Microbial growth and enzyme production for decolorization and degradation are
in uenced by different factors, such as medium composition, pH, temperature,

aeration and agitation and initial dye concentration. These factors effects have been
brie

y discussed and presented, as below.

3.1 Medium Composition

Each microbial strain has its own idiosyncratic, physiochemical and nutritional
requirement for optimal growth and enzyme production to perform the dye deg-
radation process. It is well documented that medium components greatly in

uence
the microbial growth and their interaction plays an important role in the enzyme
synthesis required for dye degradation. The industrial dye ef uents have varied

complex composition with a lack of nutrients as compared to the well de ned media

spiked with the dye used under lab conditions. Therefore, it is necessary that carbon
and nitrogen sources be supplemented along with mineral salts and other additives
(Hao et al. 2000 ).

3.2 Carbon Source

In general, the carbon source supplementation is required for microbial growth and
also to meet the suitable oxidant supply for dye decolorization by the fungus.
Majority of the studies have used glucose at a concentration of 5 10 g l − 1 . Fructose,

maltose, sucrose, xylose, cellobiose, arabinose, mannitol, glycerol, starch and
carboxymethyl cellulose were also used as alternate carbon sources in different
decolorization studies (Kumar et al. 2011 ). However, cellulose and its derivatives
were not found effective. Nevertheless, ef

-

uents from dyeing operations or dye
production units usually do not contain carbon substrates that are suitable for the
microbial assimilation. Hence, there is a necessity to add one to two carbon sources
which in uences the microbial strain performance to treat the speci c dye.

3.3 Nitrogen Source

The microbes demand nitrogen source supplementation for their growth; however,
the requirement of a speci c nitrogen source differs from organism to organism.

White-rot fungi can use both inorganic and organic nitrogen sources. Several
reports have indicated that in most cases, the rapidly metabolizable inorganic