Co-production of ligninolytic enzymes byPleurotus pulmonarius on wheat bran solid state cultures

Abstract

In this paper, the production of biomass and ligninolytic enzymes by the white-rot fungus Pleurotus pulmonarius (Fr.) Quélet cultured on wheat bran at high initial moisture was evaluated. When the initial moisture was lower than 86%, the fungal hyphae penetrated into and bound tightly to the solid-substrate particles. When the moisture was equal or higher than 86%, the growth was characterized by formation of a large mycelial mass above the substrate (surface growth). In this case, the mycelial mass could be easily separated from the residual solid substrate and quantified by gravimetric analysis. The fungus produced 0.32 g of dry mycelial mass per g of dry substrate after 15 days of cultivation. Analysis of the residual substrate showed that growth was mainly due to the consumption of soluble proteins and carbohydrates. The condition of high initial moisture strongly promoted the expression of laccase (up to 24,000 U per g of substrate or 78,000 U per g of dry fungal biomass), while the production of manganese peroxidase was negatively affected. In fact, manganese peroxidase was maximally produced when the initial moisture was 75% (2,000 U per g of substrate). The production of other enzymes, such as polysaccharidases and proteases, was not significantly affected by the initial moisture.

Lignocellulose-degrading enzyme production by white-rot Basidiomycetes isolated from the forests of Georgia

“…Among seven plant residues, mandarin peels and wheat bran caused much more enzyme accumulation as compared with other substrates. Similar observations were reported in other studies with various white-rot fungi (Mikiashvili et al 2005;Souza et al 2006;Songulashvili et al 2006Songulashvili et al , 2007Osma et al 2007) suggesting that mandarin peels and wheat bran are suitable growth substrates for expressing basidiomycete laccase activity. The highest laccase activity was obtained in fermentation of wheat bran by F. fomentarius IBB 38 (17,680 U l -1 ) and P. ostreatus IBB 10 (17,540 U l -1 ) closely followed by T. versicolor IBB 13 (15,860 U l -1 ) in SF of mandarin peelings.…”

“…The wheat bran used contained 26% cellulose, 33% hemicellulose, 47% water soluble materials, 1.6% nitrogen, and 4% lignin. This byproduct used for SSF by Pleurotus pulmonarius appeared to be an excellent substrate for high yield production of multi-enzyme complexes of carbohydrases and oxidases (Souza et al 2006). Moreover, the SF of this substrate provided high laccase activity of Ganoderma lucidum (Songulashvili et al 2007) and MnP activity of Phellinus robustus (Songulashvili et al 2006).…”

Enhanced Delignification of Lignocellulosic Biomass by Recombinant Fungus <b><i>Phanerochaete chrysosporium</i></b> Overexpressing Laccases and Peroxidases

“…The decreasing pattern of sugars indicates that fungi consumed the released sugars during the prolonged incubation, as described previously [ El-Gammal et al, 1998]. Until now, fungal methods applied on SB and WB degradation had not shown an additional improvement of hydrolyzed sugar recovery, including the combination of them with physicochemical methods [Farani de Souza et al, 2006;Fonseca-Maldonado et al, 2014;Jiang and Guo, 2016;Kuhar et al, 2008;Lima et al, 2015;Nair et al, 2015;Papinutti et al, 2003]. Even more surprising was that the amount of glucose and xylose released employing the recombinant strains was higher than previously reported using only physicochemical methods [Favaro et al, 2013;Hell et al, 2015;Liu et al, 2016;Moretti et al, 2014].…”

“…The influence of these parameters during the delignification of lignocellulosic substrates by recombinant P. chry sosporium strains remains to be determined. Despite that result, the few studies on fungal delignification from SB and WB have only achieved modest results, even with the combination of physicochemical methods [Farani de Souza et al, 2006;Khuong et al, 2014;Kuhar et al, 2008;Locci et al, 2008;Papinutti et al, 2003]. Compared to those reports employing a complete biological approach, the treatment of SB and WB with the recombinant P. chrysosporium strains showed a significant improvement in delignification, requiring up to 20% less degradation time.…”

“…In this study, the WB was found to be a better inducer for the production of ligninolytic enzymes compared to SB. This effect may be due to the release of some molecules from WB that may have an inducing function on the ligninolytic activity [Farani de Souza et al, 2006;Gnanamani et al, 2006;Verma et al, 2002]. Likewise, WB has the same effects on the production of ligninolytic enzymes in solid-state fermentation of various fungi, such as Fomes sclerodermeus, Cerrena unicolor, and Bjerkandera adusta [Papinutti et al, 2003;Songulashvili et al, 2015;Yoshida et al, 1996].…”