Chemical changes and increased degradability of wheat straw and oak wood chips treated with the white rot fungi Ceriporiopsis subvermispora and Lentinula edodes. (October 2017)

• Record Type: Journal Article
• Authors: van Kuijk, Sandra J.A.; Sonnenberg, Anton S.M.; Baars, Johan J.P.; Hendriks, Wouter H.; del Río, José C.; Rencoret, Jorge; Gutiérrez, Ana; de Ruijter, Norbert C.A.; Cone, John W.
• Is Part Of: Biomass and bioenergy. Volume 105(2017:Oct.)
• Page Start: 381
• Page End: 391
• Publication Date: 2017-10
• Subjects: Fungal treatment -- Lignocellulosic biomass -- Selective lignin degradation -- In vitro rumen degradability -- Enzymatic saccharification -- Alkylitaconic acids; Biomass energy -- Periodicals; Biomass -- Periodicals; Energy-Generating Resources -- Periodicals; Bioénergie -- Périodiques; 333.9539
• DOI: 10.1016/j.biombioe.2017.07.003
• Languages: English
• ISSNs: 0961-9534

Abstract

Abstract: Wheat straw and oak wood chips were incubated with Ceriporiopsis subvermispora and Lentinula edodes for 8 weeks. Samples from the fungal treated substrates were collected every week for chemical characterization. L. edodes continuously grew during the 8 weeks on both wheat straw and oak wood chips, as determined by the ergosterol mass fraction of the dry biomass. C. subvermispora colonized both substrates during the first week, stopped growing on oak wood chips, and resumed growth after 6 weeks on wheat straw. Detergent fiber analysis and pyrolysis coupled to gas chromatography/mass spectrometry showed a selective lignin degradation in wheat straw, although some carbohydrates were also degraded. L. edodes continuously degraded lignin and hemicelluloses in wheat straw while C. subvermispora degraded lignin and hemicelluloses only during the first 5 weeks of treatment after which cellulose degradation started. Both fungi selectively degraded lignin in wood chips. After 4 weeks of treatment, no significant changes in chemical composition were detected. In contrast to L. edodes, C. subvermispora produced alkylitaconic acids during fungal treatment, which paralleled the degradation and modification of lignin indicating the importance of these compounds in delignification. Light microscopy visualized a dense structure of wood chips which was difficult to penetrate by the fungi, explaining the relative lower lignin degradation compared to wheat straw measured by chemical analysis. All these changes resulted in an increased in in vitro rumen degradability of wheat straw and oak wood chips. In addition, more glucose and xylose were released after enzymatic saccharification of fungal treated wheat straw compared to untreated material. Highlights: Combining chemical, visual and utilization analysis shows fungal delignification. Formation of fungal biomass does not always follow degradation of lignocellulose. C. subvermispora and L. edodes have a different mechanism of lignin degradation. Fungal treatment results in an increased utilization of wheat straw and wood chips. Alkylitaconic acids production is important for selective delignification. Density of the tissue limits fungal delignification.