C. globosum grew on ITE metabolizing dyes and other intermediate
metabolites and then reducing COD and color. The maximum
OD620 and COD reductions yields of 99.8% and 88.4%, respectively
(Fig. 5b) were obtained under agitation. Therefore, stirring
improved mycelia growth and accelerated OD620 and COD removal
rates due to better hydrodynamic conditions. Several authors reported
that the process of ITE decolourization is due to the combination
of two ways. The first is biological, which is provided by
the secretion of extracellular enzymes, allowing the biodegradation
of the dye. The second is the physical adsorption of dyes on the
strain surface at specific membrane receptors, which participates in
the decolourization (Bhatnagar and Sillanpaa, 2010; Chen and Ting,
2015).
In this work, both phenomena were occurred simultaneously. In
the first 48 h there's an adsorption of the dye on the mycelium
coupled to the bioconversion of complex molecules inducing the
rapid OD620 removal at high rate (Fig. 4c). The COD removal started
later and increased during the time (Fig. 4c). In fact, a good
biodegradation has observed until the 4th day which can be
demonstrated by the secretion of ligninolytic enzymes with high
activities, which is not observed at the beginning of the experiment
(Fig. 5) especially for the stirred fermentation.
In order to confirm that the