Decolorization in the Reactor

The results are summarized as follows for a 15-day reactor cycle. The desirable characteristics of vigorous growth and rapid decolorization (Joyce et al. 1984) were achieved by omitting veratryl alcohol from the medium in the reactor cycle. In this case, the nitrogen was consumed in 24 h and glucose in 48 h. The phenoloxidase reached a level of 4.8 units of ABTS* oxidized/ml on day 9 and then declined to remain at a relatively steady level of 1.85 U/ml for the rest of the cycle. This decrease broadly coincided with detection of autolytic activity and reappearance of nitrogen in the medium. The dark effluent was rapidly decolorized during the first 24 h. The fungal mycelium was originally dark suggesting the adsorption of some of the solid by the mycelium. This intensity decreased over the 15-day cycle until the mycelium became indistinguishable from the control. The final effluent was a light yellow.

There were differences in the spectra at different stages of decolorization of the effluent and some of these are shown in Figure 1. In this increased decolorizing effect three stages are suggested. Firstly some of the color adsorbs to the enhanced mycelial mass formed in the absence of veratryl alcohol. Secondly, the phenoloxidase acts to decolorize the soluble dye components of the effluent and thirdly the phenoloxidase acts on the adsorbed color of the mycelium in situ. Evidence that the phenoloxidase was most probably a laccase is reported in Section 6.

Making Your Own Wine

Making Your Own Wine

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