Biological wheat straw valorization: Multicriteria optimization of Polyporus brumalis pretreatment in packed bed bioreactor

Abstract

The purpose of this work was to optimize the pretreatment process of wheat straw by Polyporus brumalis_BRFM985 in order to improve carbohydrate accessibility for more efficient bioconversion. Indeed, there is growing demands to develop sustainable routes for lignocellulosic feedstocks valorization into value‐added products in energy, chemicals, materials, and animal feed fields. To be achieved, implementation of cheap and ecofriendly biomass pretreatment processes is necessary. In this frame, white rot basidiomycetes, well known for their ability to degrade lignin efficiently and selectively, are of great interest. The pretreatment of wheat straw by Polyporus brumalis_BRFM985 was performed in packed bed bioreactor and optimized using response surface methodology. The four pretreatment parameters optimized were metals addition (Cu, Mn, and Fe), time of culture, initial water content, and temperature. Multicriteria optimization highlighted that wheat straw pretreatment by Polyporus brumalis_ BRFM985 in the presence of metals with high initial water content of 3.6 g H2O/g at 27°C for 15–16 days led to an improvement of carbohydrate accessibility with minimal matter loss.

Integrative visual omics of the white-rot fungus Polyporus brumalis exposes the biotechnological potential of its oxidative enzymes for delignifying raw plant biomass

“…The fungus was maintained on 2% (w/v) malt extract, 2% (w/v) agar at 4 °C. Inoculum preparation and SSF procedures were performed as described by Zhou et al [ 12 ]. Briefly, the fungal inoculum was prepared by grinding mats (Ultra-Turrax, 60 s, 9500 rpm) obtained from 7-day-old Roux flasks (malt extract 2%, w/v).…”

“…Biochemical composition (klason lignin, cellulose and hemicelluloses) of the fermented wheat straw was determined in duplicate according to the NERL method [ 42 ]. Carbohydrate accessibility to enzymatic degradation was evaluated by measuring carbohydrate net conversion yields as described by Zhou et al [ 12 ]. Briefly, control or fermented wheat straw was subjected to mild alkali treatment, followed by a 72 h enzymatic hydrolysis with 12 FPU/g substrate (dw) of cellulases from Trichoderma reesei (GC220, Genencor Danisco) and 60 U/g substrate (dw) of β-glucosidase from Aspergillus niger (Novozyme SP188, Sigma).…”

“…A recent screen of 63 white-rot fungal strains for selective delignification of wheat straw under solid-state fermentation (SSF) highlighted Polyporus brumalis BRFM 985 as the best performing strain [ 11 ]. The cultivation of the fungus for 2 weeks on wheat straw significantly improved the accessibility of cellulase-rich enzymatic cocktails to residual carbohydrates [ 12 ].…”

Integrative visual omics of the white-rot fungus Polyporus brumalis exposes the biotechnological potential of its oxidative enzymes for delignifying raw plant biomass

“…A recent screen of 63 white-rot fungal strains for selective delignification of wheat straw under solid-state fermentation (SSF) highlighted Polyporus brumalis BRFM 985 as the best performing strain (11). The cultivation of the fungus for two weeks on wheat straw significantly improved the accessibility of cellulase-rich enzymatic cocktails to residual carbohydrates (12).…”

“…Biochemical composition (klason lignin, cellulose and hemicelluloses) of the fermented wheat straw was determined in duplicate according to the NERL method (14). Carbohydrate accessibility to enzymatic degradation (hereinafter referred as carbohydrate digestibility) was evaluated as described by Zhou et al (12). Briefly, control or fermented wheat straw were subjected to mild alkali treatment, followed by a 72h enzymatic hydrolysis with 12 FPU/g substrate (dw) of cellulases from Trichoderma reesei (GC220, Genencor Danisco) and 60 U/g substrate (dw) of β-glucosidase from Aspergillus niger (Novozyme SP188, Sigma).…”