Rational design of Aspergillus flavus A5p1-immobilized cell system to enhance the decolorization of reactive blue 4 (RB4)

Abstract

Anthraquinone dyes are a class of typical carcinogenic and hard-biodegradable organic pollutants. This study aimed to enhance the decolorization of anthraquinone dye by rationally designing an expected immobilized system. Reactive blue 4 (RB4) was used as a substrate model and a previous isolated dye-degrading strain Aspergillus flavus A5p1 was purposefully immobilized. Considering the effects of cell attachment and mass transfer, the polyurethane foam (PUF) with open pore structure was selected as the immobilization carrier. Results showed that the RB4 decolorization efficiency was significant enhanced after immobilization. Compared to the free mycelium system, the decolorization time of 200 mg·L −1 RB4 was shortened from 48 h to 28 h by the PUF-immobilized cell system. Moreover, the PUF-immobilized system could tolerate RB4 up to 2000 mg·L −1 . In the packed bed bioreactor (PBBR), an average decolorization efficiency of 93.3% could be maintained by the PUF-immobilized system for 26 days. The decolorization process of RB4 was well described by the logistic equation and the degradation pathway was discussed. It was found that the higher specific growth rate of the PUF-immobilized cells was one of reasons for the enhanced decolorization. The good performance of the PUF-immobilized cell system would make it have potential application value for RB4 bioremediation.