Background: As one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays. Results: In this study, a consortium of white rot fungi composed of Lenzites betulina and Trametes versicolor was employed to enhance the ligninolytic enzyme activity of laccase (Lac) and manganese peroxidase (MnP) under microbial synergism. The maximum enzymatic activity of Lac and MnP was individually 18.06 U mL⁻¹ and 13.58 U mL⁻¹ along with a lignin degradation rate of 50% (wt/wt), which were achieved from batch cultivation of the consortium. The activities of Lac and MnP obtained from the consortium were both improved more than 40%, as compared with monocultures of L. betulina or T. versicolor under the same culture condition. The enhanced biodegradation performance was in accordance with the results observed from scanning electron microscope (SEM) of lignin samples before and after biodegradation, and secondary-ion mass spectrometry (SIMS). Finally, the analysis of heteronuclear single quantum coherence (HSQC) NMR and gas chromatography–mass spectrometry (GC–MS) provided a comprehensive product mapping of the lignin biodegradation, suggesting that the lignin has undergone depolymerization of the macromolecules, side-chain cleavage, and aromatic ring-opening reactions. Conclusions: Our results revealed a considerable escalation on the enzymatic activity obtained in a short period from the cultivation of the L. betulina or T. versicolor due to the enhanced microbial synergistic effects, providing a potential bioconversion route for lignin utilization.

Industrial waste lignin can be used as a sustainable resource to prepare carbon materials, which has been considered an important strategy for the substitution of coal-based carbon. However, a review summarizing the design mechanism of heteroatom-doped lignin-derived carbon materials and their application performance is lacking. Herein, we reviewed the recent progress on heteroatom-doped lignin-based carbon applied in energy storage applications such as batteries and capacitors, environmental fields such as removing contaminants from the air and water, substance testing for iron/chromium ions, and catalysis. More importantly, we present a critical discussion with respect to the effect of heteroatom-doping (e.g., N-doping and N/S/O/P co-doping) on the physicochemical properties including the BET area, defect structure, hydrophilicity/hydrophobicity, electric conductivity, and electron density of lignin-based carbon materials. Particularly, the effects of the above-mentioned properties on the reversible capacity, rate performance, and cycling performance of batteries; the capacitance and energy density of capacitors; and the adsorption capacity of lignin-based carbonaceous adsorbents for the removal of pollutants are concluded. Finally, we propose the future perspective and challenges in applying lignin-based carbon materials in energy storage and environmental fields.