Secretome analysis of Trichoderma reesei CICC41495 for degradation of arabinoxylan in malted barley

Abstract

Arabinoxylan, one of the major non‐starch polysaccharides of the endosperm cell wall of barley, has a negative impact on the filterability of wort and beer. The addition of microbial xylanase would be an effective strategy to degrade arabinoxylan. In this study, the secretome of Trichoderma reesei CICC 41495 cultivated under submerged fermentation with wheat bran as a carbon source was characterised by two‐dimensional electrophoresis combined with MALDI‐TOF/TOF tandem mass spectrometry. A total of 24 proteins were identified in the culture supernatant, 23 of which were involved in non‐starch polysaccharide degradation. The proteins belonged to 10 different families of glycoside hydrolases, including xyloglucanase, cellobiohydrolase I, cellobiohydrolase II, endoglucanase II, endo‐1,4‐β‐glucanase VII, β‐glucosidase, endo‐1,4‐β‐xylanase I and II, endo‐1,4‐β‐xylanase III, and α‐l‐arabinofuranosidase. Of these, four were correlated with arabinoxylan degradation. Supplementation of the secretome loading of 0.14 mg protein/g malt to mash resulted in the total degradation of high molecular weight arabinoxylan, a 90% increase in filtration rate and a 7.9% decrease in viscosity. The results suggest that T. reesei produces a tailored xylanolytic enzyme system that efficiently hydrolysed high molecular weight arabinoxylan. Accordingly, the secretome of this fungi has potential value in the brewing industry. © 2018 The Institute of Brewing & Distilling

A Glycoside Hydrolase Family 62 A-L-Arabinofuranosidase from Trichoderma Reesei and Its Applicable Potential during Mashing

“…However, the GH families of both AFases mentioned above are not clear. In this paper, only one AFase, which belongs to GH62, has been purified and identified, which is consistent with previous results [18]. The family GH62 exclusively contains AFases secreted by fungi or bacteria [15].…”

“…Reports concerning AFases from T. reesei are quite limited. In previous work, we have found a complete xylanolytic enzyme system in the culture filtrate of T. reesei CICC 41,495 by secretome analysis [18]. This research focusses on the AFase isolated from that crude mixture of xylanolytic enzymes.…”

Prediction of potential malt extract and beer filterability using conventional and novel malt assays

“…Accordingly, Sun et al . , recently observed that the inclusion of a combination of xylanase enzymes from Trichoderma reesei with a mash decreased viscosity by 8%. These conclusions were in accordance to the observations by Schwarz and Han that arabinoxylan levels in commercial beers were ~10 times higher than those of β ‐glucans.…”

“…Previous studies on the arabinoxylan content in wort by Li et al (20) and particularly by Sadosky et al (19), have suggested that the contribution of arabinoxylan to viscosity is at least of equal importance to that of β-glucan. Accordingly, Sun et al (69), recently observed that the inclusion of a combination of xylanase enzymes from Trichoderma reesei with a mash decreased viscosity by 8%. These conclusions were in accordance to the observations by Schwarz and Han (70) that arabinoxylan levels in commercial beers were~10 times higher than those of β-glucans.…”

The effect of barley infected with xylanase‐producing filamentous fungi on premature yeast flocculation

“…Xylanase activity was measured using 1% (w/v) wheat arabinoxylan as substrate. Hydrolysis of the polymer was monitored using the dinitrosalicylic acid method (DNS) by measuring the reducing sugars from enzymatic activity at 540 nm (Sun et al, 2018). One unit of xylanase activity was defined as the amount of enzyme required to degrade xylan to produce 1 μmol xylose per minute under the conditions of the assay.…”