The production of seed oils from Cynara cardunculus generates huge amounts of lignocellulosic residues which can be exploited according to a cascade approach. In this paper, residual cardoon biomass (RCB) was tested as a growth substrate for the solid-state production of cellulolytic cocktails by species known to produce glucose-tolerant β-glucosidase isoenzymes. Best productions were obtained with 10-d-old Aspergillus tubingensis cultures on RCB supplemented with wheat bran (200 g kg−1) yielding β-glucosidase and endo-β-1,4-glucanase activities as high as (25 and 4) IU g−1, respectively, and 4 FPU g−1. The saccharification performance of the obtained cocktail tested on acid-catalysed steam-exploded RCB at low solid loading (25 g dm−3) was around 53% at 20 FPU g−1 cellulose. These performance were significantly enhanced by adding the xylanase-rich NS 22083 commercial formulation, reaching glucose yields higher than 80% after 72 h incubation. The use of the catalytic additive was optimized by a statistical approach, based on factorial analysis. A comparison of the performance of the A. tubingensis reinforced cocktail with the Cellic®CTec2 taken as benchmark formulation was done at the same enzyme load and performed at industrially relevant solid loadings, namely at (100 and 200) g dm−3. This comparison showed that Cellic®CTec2 led to only slightly higher glucose yields while an opposite outcome was observed for xylose yields, irrespective of the solid loading conditions. Thus, this study shows that an in-house enzyme production, based on the solid-state conversion of an industrial byproduct, able of yielding cellulolytic cocktails with substantial saccharification performance is feasible.

Cynara cardunculus a novel substrate for solid-state production of Aspergillus tubingensis cellulases and sugar hydrolysates

Liuzzi F.;de Bari I.;
2019

Abstract

The production of seed oils from Cynara cardunculus generates huge amounts of lignocellulosic residues which can be exploited according to a cascade approach. In this paper, residual cardoon biomass (RCB) was tested as a growth substrate for the solid-state production of cellulolytic cocktails by species known to produce glucose-tolerant β-glucosidase isoenzymes. Best productions were obtained with 10-d-old Aspergillus tubingensis cultures on RCB supplemented with wheat bran (200 g kg−1) yielding β-glucosidase and endo-β-1,4-glucanase activities as high as (25 and 4) IU g−1, respectively, and 4 FPU g−1. The saccharification performance of the obtained cocktail tested on acid-catalysed steam-exploded RCB at low solid loading (25 g dm−3) was around 53% at 20 FPU g−1 cellulose. These performance were significantly enhanced by adding the xylanase-rich NS 22083 commercial formulation, reaching glucose yields higher than 80% after 72 h incubation. The use of the catalytic additive was optimized by a statistical approach, based on factorial analysis. A comparison of the performance of the A. tubingensis reinforced cocktail with the Cellic®CTec2 taken as benchmark formulation was done at the same enzyme load and performed at industrially relevant solid loadings, namely at (100 and 200) g dm−3. This comparison showed that Cellic®CTec2 led to only slightly higher glucose yields while an opposite outcome was observed for xylose yields, irrespective of the solid loading conditions. Thus, this study shows that an in-house enzyme production, based on the solid-state conversion of an industrial byproduct, able of yielding cellulolytic cocktails with substantial saccharification performance is feasible.
Aspergillus tubingensis; Cellulase production; Cynara cardunculus; Solid-state fermentation; Steam explosion biomass saccharification
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12079/52171
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