Lignin valorization: Status, challenges and opportunities.

Genetically engineered microbial remediation of soils co-contaminated by heavy metals and polycyclic aromatic hydrocarbons: Advances and ecological risk assessment.

Microbial valorization of lignin: Prospects and challenges.

Microbial valorization of lignin: Prospects and challenges

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. 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. 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.

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Enhanced Lignin Biodegradation by Consortium of White rot Fungi: Microbial Synergistic Effects and Product Mapping

Lignin, the most abundant renewable aromatic compound in nature, is an excellent feedstock for value-added bioproducts manufacturing; while the intrinsic heterogeneity and recalcitrance of which hindered the efficient lignin biorefinery and utilization. Compared with chemical processing, bioprocessing with microbial and enzymatic catalysis is a clean and efficient method for lignin depolymerization and conversion. Generally, lignin bioprocessing involves lignin decomposition to lignin-based aromatics via extracellular microbial enzymes and further converted to value-added bioproducts through microbial metabolism. In the review, the most recent advances in degradation and conversion of lignin to value-added bioproducts catalyzed by microbes and enzymes were summarized. The lignin-degrading microorganisms of white-rot fungi, brown-rot fungi, soft-rot fungi, and bacteria under aerobic and anaerobic conditions were comparatively analyzed. The catalytic metabolism of the microbial lignin-degrading enzymes of laccase, lignin peroxidase, manganese peroxidase, biphenyl bond cleavage enzyme, versatile peroxidase, and β-etherize was discussed. The microbial metabolic process of H-lignin, G-lignin, S-lignin based derivatives, protocatechuic acid, and catechol was reviewed. Lignin was depolymerized to lignin-derived aromatic compounds by the secreted enzymes of fungi and bacteria, and the aromatics were converted to value-added compounds through microbial catalysis and metabolic engineering. The review also proposes new insights for future work to overcome the recalcitrance of lignin and convert it to value-added bioproducts by microbial and enzymatic catalysis.

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Depolymerization and conversion of lignin to value-added bioproducts by microbial and enzymatic catalysis

Metabolic engineering of Cupriavidus necator H16 for improved chemoautotrophic growth and PHB production under oxygen-limiting conditions.

Co-conversion of lignocellulose-derived glucose, xylose, and aromatics to polyhydroxybutyrate by metabolically engineered Cupriavidus necator.

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Perceptual assimilation of Mandarin non-sibilant fricatives by speakers of Quanzhou Southern Min

This study explores the discrimination of Mandarin non-sibilant fricatives by bilingual speakers (N = 40) of Quanzhou Southern Min (L1) and Mandarin (L2) in different phonological contexts, including rounded vowels and the glide [w]. The results of the ABX discrimination task indicate significant contextual effects of the following sound, in line with predictions based on the Perceptual Assimilation model (PAM) [Best (1995). J. Phon. 20(3), 305-330]. Additionally, the observed result could not be fully explained by the acoustic distance between stimuli, and discrimination ability was better for speakers with more exposure to and use of Mandarin.

Caihong Weng

Papers

Depolymerization and conversion of lignin to value-added bioproducts by microbial and enzymatic catalysis

Metabolic engineering of Cupriavidus necator H16 for improved chemoautotrophic growth and PHB production under oxygen-limiting conditions.

Co-conversion of lignocellulose-derived glucose, xylose, and aromatics to polyhydroxybutyrate by metabolically engineered Cupriavidus necator.

Perceptual assimilation of Mandarin non-sibilant fricatives by speakers of Quanzhou Southern Min

Bilingual phonological contrast perception: The influence of Quanzhou Southern Min on Mandarin non-sibilant fricative discrimination.