A novel thermostable xylanase GH10 from Malbranchea pulchella expressed in Aspergillus nidulans with potential applications in biotechnology

Abstract

BackgroundThe search for novel thermostable xylanases for industrial use has intensified in recent years, and thermophilic fungi are a promising source of useful enzymes. The present work reports the heterologous expression and biochemical characterization of a novel thermostable xylanase (GH10) from the thermophilic fungus Malbranchea pulchella, the influence of glycosylation on its stability, and a potential application in sugarcane bagasse hydrolysis.ResultsXylanase MpXyn10A was overexpressed in Aspergillus nidulans and was active against birchwood xylan, presenting an optimum activity at pH 5.8 and 80°C. MpXyn10A was 16% glycosylated and thermostable, preserving 85% activity after 24 hours at 65°C, and deglycosylation did not affect thermostability. Circular dichroism confirmed the high alpha-helical content consistent with the canonical GH10 family (β/α)8 barrel fold observed in molecular modeling. Primary structure analysis revealed the existence of eight cysteine residues which could be involved in four disulfide bonds, and this could explain the high thermostability of this enzyme even in the deglycosylated form. MpXyn10A showed promising results in biomass degradation, increasing the amount of reducing sugars in bagasse in natura and in three pretreated sugarcane bagasses.ConclusionsMpXyn10A was successfully secreted in Aspergillus nidulans, and a potential use for sugarcane bagasse biomass degradation was demonstrated.

An immobilized bifunctional xylanase on carbon-coated chitosan nanoparticles with a potential application in xylan-rich biomass bioconversion

“…The cellulose binding and hydrolyzing activity gave ATXX an advantage when reacting with the natural complex substrate, such as wheat bran, corn cob and straw. Ribeiro et al [5] reported that the recombinant thermophilic and thermotolerant Malbranchea pulchella xylanase hydrolyzed pretreated sugarcane bagasse and released the reducing sugar with high concentration. The wheat bran insoluble xylan was hydrolyzed to a mixture of XOs (X2-X6) with relatively high concentration of X3, X4, and X5 by immobilized ATXX (Fig.…”

“…Endo-␤-1, 4-xylanase (EC 3.2.1.8, further referred to as xylanase) is one of the important enzymes involved in the degradation of xylan, which is the most abundant natural cell wall polysaccharide after cellulose [1][2][3]. In past 20 years, xylanase has drawn considerable research interest mainly because of its known and potential application, such as production of xylooligosaccharides (XOs) in the food industry and conversion of agricultural by-product into reducing sugar [4][5][6][7]. These applications need enzymes to retain high activity after being used several times at drastic process conditions (high temperature, high ion concentration, acidic, or alkaline environment) and to easily recover from reaction mixtures for reuse.…”

Xylanase production from a new strain of Aspergillus terreus S9 and its application for saccharification of rice straw using combinatorial approach

“…Saccharification of the agricultural residues by apt pretreatment and enzymatic hydrolysis is of great significance for production of various commercial products [1,3,9,12]. Enzymatic hydrolysis of wheat straw pretreated with dilute alkali and acid with crude xylanase from Aspergillus tubingensis JP-1 yielded 688 and 543 mg/g reducing sugar, respectively [29].…”

“…Being an heteropolysaccharide xylan requires several enzymes for its complete breakdown but endo b-(1,4)-xylanase or simply xylanase (EC 3.2.1.8), is the main enzyme which cleaves the internal b-(1,4)-linked Dxylosyl glycosidic bonds in heteroxylan [6,7]. Xylanases may have application potential for several biotechnological processes such as pulp and paper industries for biobleaching, nutrition-rich animal feed production, bioconversion of LB into simple sugars that can be fermented to produce bioethanol/butanol (biofuel), xylitol, and a variety of other platform chemicals/materials of commercial importance [3,8,9].…”

“…Ever-increasing world energy-demand, depleting fossil fuel reserves, and growing environmental concerns motivated a tremendous research impetus on development of renewable energy sources [1,2]. Lignocellulosic biomass (LB) represented mainly by agricultural/forestry residues are the most plenteous feed stock that can be exploited for production of energy and high value specialty chemicals [3]. Xylan constitutes one of the major hemicellulosic component of LB, and consists primarily of a backbone of b-1,4-linked-Dxylopyranosyl residues and side chains with varying substituent groups [4,5].…”