Abstract
White-rot fungus is a common lignin-degrading fungus. However, compared with those of microorganisms that biodegrade lignin alone, synergistic systems of electro-Fenton processes and white-rot fungi are superior because of their high efficiency, mild conditions, and environmental friendliness. To investigate the details of lignin degradation by a synergistic system comprising electro-Fenton processes and white-rot fungi, lignin degradation was studied at different voltages with three lignin-degrading fungi (Phanerochaete chrysosporium, Lentinula edodes, and Trametes versicolor). The lignin degradation efficiency (82∼89%) of the synergistic systems at 4 V was higher than that of a control at 96 h post inoculation. Furthermore, the H2O2 produced and phenolic lignin converted in the system can significantly enhance the efficiency of ligninolytic enzymes, so a considerably increased enzyme activity was obtained by the synergistic action of electro-Fenton processes and white-rot fungi. 13C NMR spectroscopy revealed that aromatic structure units (103–162 ppm) were effectively degraded by the three fungi. This study shows that the combination of electro-Fenton processes and white-rot fungi treatment significantly improved the lignin degradation efficiency, which established a promising strategy for lignin degradation and valorization.
Highlights
In the degradation of lignin by microorganisms, synergistic systems have a more significant degradation effect than have systems without synergy
The results showed that different voltages had different effects on the three white-rot fungi; and 1, 2, 3, and 4 V promoted the growth of the three white-rot fungi to varying degrees
In the presence of white-rot fungi and an applied voltage, the degradation rates of lignin for P. chrysosporium, T. versicolor, and L. edodes at 4 V were 82, 86, and 89%, respectively, which were 65– 70% higher than those obtained with white-rot fungi or applied voltage alone. These results indicate that a synergistic effect on lignin degradation occurred in the presence of white-rot fungi and applied voltage
Summary
In the degradation of lignin by microorganisms, synergistic systems have a more significant degradation effect than have systems without synergy This is due to the non-specific, complex spatial structure of lignin. High-lignin materials have heterogeneity and structural stability, which are due to the formation and fracture modes of chemical bonds between complex chemical groups, conversions between different chemical groups, and various random interactions. These are the reasons considered challenging for the microbial degradation of aromatic compounds (Wen et al, 2013)
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