Selective delignification of poplar wood with a newly isolated white-rot basidiomycete Peniophora incarnata T-7 by submerged fermentation to enhance saccharification

Abstract

Background Pretreatment is a critical step required for efficient conversion of woody biomass into biofuels and platform chemicals. Fungal pretreatment is regarded as one of the most promising technology for woody biomass conversion but remains challenging for industrial application. The exploration of potential fungus strain with high efficient delignification and less processing time for woody biomass pretreatment will be valuable for development of biorefinery industry. Here, a newly isolated white-rot basidiomycete Peniophora incarnate T-7 was employed for poplar wood pretreatment. Results The chemical component analysis showed that cellulose, hemicellulose and lignin from poplar wood declined by 16%, 48% and 70%, respectively, after 7 days submerged fermentation by P. incarnate T-7. Enzymatic saccharification analysis revealed that the maximum yields of glucose and xylose from 7 days of P. incarnate T-7 treated poplar wood reached 33.4% and 27.6%, respectively, both of which were enhanced by sevenfold relative to the untreated group. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) characterization confirmed that lignocellulosic structure of poplar wood was largely broken by P. incarnate T-7, including delignification and de-crystalline of cellulose. Meanwhile, lignin component of poplar wood was selectively degraded by P. incarnate T-7, and G-type unit of lignin was preferentially attacked by the strain. Furthermore, quantitative proteomic analysis revealed that a considerable amount of lignocellulolytic enzymes were detected in the secretory proteins of P. incarnate T-7, especially with high abundance of lignin-degrading enzymes and hemicellulases. Combination of quantitative proteomic with transcriptomic analysis results showed that most of those lignocellulolytic enzymes were highly upregulated on poplar wood substrate compared to glucose substrate. Conclusions This study showed that P. incarnate T-7 could selectively delignify poplar wood by submerged fermentation with short time of 7 days, which greatly improved its enzymatic saccharification efficiency. Our results suggested that P. incarnate T-7 might be a promising candidate for industrial woody biomass pretreatment.

Comparative Analysis of Peniophora lycii and Trametes hirsuta Exoproteomes Demonstrates “Shades of Gray” in the Concept of White-Rotting Fungi

“…Moreover, on all media, P. lycii LE-BIN 2142 predominantly secreted an FAD-binding domain-containing protein provisionally assigned to the AA7 CAZyme family. In accordance with our data, Ma et al [ 17 ] previously showed that P. incarnata T-7, cultivated in the presence of poplar wood, and Peniophora sp. CBMAI 1063 [ 16 ], cultivated in a bioreactor on a nutritionally reach medium supplemented with CuSO 4 , did not secrete ligninolytic type II peroxidases.…”

“…CBMAI 1063 cultivated in a bioreactor on a nutritionally rich medium supplemented with CuSO 4 , although cellulases of GH3 and 5 CAZyme families were detected, their relative abundances (measured as spectral count) were significantly lower than that of LPMO and GMC oxidoreductases [ 16 ]. Similarly, while LPMO and GMC oxidoreductases were detected in the exoproteome of Peniophora incarnata T-7 grown in poplar wood-containing media, typical cellulases such as endoglucanases and exoglucanases were absent [ 17 ]. Regarding hemicellulases, the exoproteome of Peniophora sp.…”

“…CBMAI 1063 was also poor in this type of enzyme [ 16 ]. P. incarnata T-7 secreted many hemicellulases during its growth on poplar wood, although, oddly enough, the same hemicellulases but in smaller amounts were produced on a control medium containing glucose as the only carbon source [ 17 ].…”

“…In this article, P lycii LE-BIN 2142 and T. hirsuta LE-BIN 072 were compared and contrasted in terms of their enzymatic machinery used for degradation of different types of wood substrates—alder, birch and pine sawdust. To the best of our knowledge, this is the third article reporting exoproteomes of a fungus from the Peniophora genus; the other two are Brenelli et al [ 16 ] and Ma et al [ 17 ]. Additionally, growth patterns of these fungi on various types of sawdust and on substrates that are the main components of plant cell walls (cellulose, xylan and lignin) were investigated.…”

Lignocellulose dissociation with biological pretreatment towards the biochemical platform: A review

“…Ma et al. [ 40 ] reported a newly isolated white-rot basidiomycete Peniophora incarnate T-7 that could be employed for poplar wood pretreatment. Significant groups of lignin-degrading enzymes, including laccase, multicopper oxidase, peroxidase and other auxiliary enzymes, were identified in proteins secreted by the strain.…”