Secretome analysis of Pleurotus eryngii reveals enzymatic composition for ramie stalk degradation

Abstract

Pleurotus eryngii (P. eryngii) can secrete large amount of hydrolytic and oxidative enzymes to degrade lignocellulosic biomass. In spite of several researches on the individual lignolytic enzymes, a direct deconstruction of lignocellulose by enzyme mixture is not yet possible. Identifying more high-performance enzymes or enzyme complexes will lead to efficient in vitro lignocelluloses degradation. In this report, secretomic analysis was used to search for the new or interesting enzymes for lignocellulose degradation. Besides, the utilization ability of P. eryngii to ramie stalk substrate was evaluated from the degradation of cellulose, hemicellulose, and lignin in medium and six extracellular enzymes activities during different growth stages were discussed. The results showed that a high biological efficiency of 71% was obtained; cellulose, hemicelluloses, and lignin decomposition rates of P. eryngii were 29.2, 26.0, and 51.2%, respectively. Enzyme activity showed that carboxymethyl cellulase, xylanase, laccase, and peroxidase activity peaks appeared at the primordial initiation stage. In addition, we profiled a global view of the secretome of P. eryngii cultivated in ramie stalk media to understand the mechanism behind lignocellulosic biomass hydrolysis. Eighty-seven nonredundant proteins were identified and a diverse group of enzymes, including cellulases, hemicellulases, pectinase, ligninase, protease, peptidases, and phosphatase implicated in lignocellulose degradation were found. In conclusion, the information in this report will be helpful to better understand the lignocelluloses degradation mechanisms of P. eryngii.

Time-scale dynamics of proteome and transcriptome of the white-rot fungus Phlebia radiata: growth on spruce wood and decay effect on lignocellulose

“…Phlebioid clade includes fungal species completely lacking laccase encoding genes in their genomes, such as Phanerochaete chrysosporium, Phanerochaete carnosa, and Phlebiopsis gigantea [36, 57, 58]. On the contrary, lignocellulose secretomes of more far-related white-rot fungal species from other systematic clades and orders of Agaricomycetes demonstrate a wider array of laccase proteins, e.g., in C. subvermispora (three detected laccases on lignocellulose), Pleurotus eryngii (four detected laccases), and Pleurotus ostreatus (four detected laccases) [39, 43, 45, 59]. In this respect, the phlebioid white-rot fungi demonstrate their own type of (less or non-laccase dependent) strategies of wood-decay.…”

The saprotrophic Pleurotus ostreatus species complex: late Eocene origin in East Asia, multiple dispersal, and complex speciation

“…The close association between fungi and plants is also likely to be an important factor influencing the distribution of fungi (Malloch et al 1980). Well known as the white-rot SPF, the P. ostreatus species complex exhibits wood-decay properties that cause degradation of components of the substrate plant cell wall (PCW), including lignin, cellulose, and hemicelluloses (Sánchez 2009;Xie et al 2016). Although belonging to the same complex, substrate specificity or preference for decayed wood is characterized by the P. ostreatus species complex taxa: most species of the P. ostreatus complex have been reported on deciduous and coniferous trees, such as Fagaceae, Betulaceae, Salicaceae and Pinaceae (Albertó et al 2002;Liu et al 2015Liu et al , 2016Petersen and Hughes 1997;Petersen and Krisai-Greilhuber 1996;Vilgalys et al 1993;Vilgalys and Sun 1994b), whereas species in Clade IIId grow in association with plant roots or stems of Apiaceae (Eryngium, Ferula, Ferulago, Cachrys, Laserpitium, Diplotaenia and Elaeoselinum) (Boisselier-Dubayle 1983;Bresinsky et al 1987;Hilber 1982;Joly et al 1990;Mou et al 1987;Venturella 2000Venturella , 2002Venturella et al 2016;Zervakis et al 2014;Zervakis and Venturella 1998;Zhang et al 2006;Zhao et al 2016aZhao et al , 2016b.…”

“…Association with coniferous or deciduous logs appeared to be an ancestral character in the P. ostreatus species complex, followed by transitions to stems or roots of herbaceous Apiaceae. Recently, the genomic data provided insights into genomic basis of lignocellulose degradation mechanisms between P. ostreatus and P. eryngii (Xie et al 2016;Yang et al 2016;Zhang et al 2018). Furthermore, it has been inferred that the substrate plants may have had an effect on the genetic differentiation among the species in Clade IIId due to competition for ecological niches (Zervakis et al 2014).…”

The complete mitochondrial genome of the Basidiomycete edible fungus Pleurotus eryngii

“…These fungi can secrete a diversity of extracellular enzymes (cellulases, hemicellulases, pectinases, ligninases, proteases, peptidases and so on) that can break down complex plant biomolecules, including cellulose, hemicellulose and lignin (Cohen et al 2002;Yao & Jin 2004;Xie et al 2016). As such, they play an essential role in nutrient cycling in natural environments.…”