Characterization of a GH5 endoxylanase from Penicillium funiculosum and its synergism with GH16 endo-1,3(4)-glucanase in saccharification of sugarcane bagasse

Abstract

The production of second-generation fuels from lignocellulosic residues such as sugarcane bagasse (SCB) requires the synergistic interaction of key cellulose-degrading enzymes and accessory proteins for their complete deconstruction to useful monomeric sugars. Here, we recombinantly expressed and characterized unknown GH5 xylanase from P. funiculosum (PfXyn5) in Pichia pastoris, which was earlier found in our study to be highly implicated in SCB saccharification. The PfXyn5 has a molecular mass of ~ 55 kDa and showed broad activity against a range of substrates like xylan, xyloglucan, laminarin and p-nitrophenyl-β-d-xylopyranoside, with the highest specific activity of 0.7 U/mg against xylan at pH 4.5 and 50 °C. Analysis of the degradation products of xylan and SCB by PfXyn5 showed significant production of xylooligosaccharides (XOS) with a degree of polymerization (DP) ranging from two (DP2) to six (DP6), thus, suggesting that the PfXyn5 is an endo-acting enzyme. The enzyme synergistically improved the saccharification of SCB when combined with the crude cellulase cocktail of P. funiculosum with a degree of synergism up to 1.32. The PfXyn5 was further expressed individually and simultaneously with a notable GH16 endoglucanase (PfEgl16) in a catabolite-derepressed strain of P. funiculosum, PfMig188, and the saccharification efficiency of the secretomes from the resulting transformants were investigated on SCB. The secretome of PfMig188 overexpressing Xyn5 or Egl16 increased the saccharification of SCB by 9% or 7%, respectively, over the secretome of PfMig188, while the secretome of dual transformant increased SCB saccharification by ~ 15% at the same minimal protein concentration.

A Glycosyl Hydrolase 5 Family Protein Is Essential for Virulence of Necrotrophic Fungi and Can Suppress Plant Immunity

“…Glycosyl hydrolase 5 family proteins have been studied for decades and are involved in many biomolecular hydrolysis processes, it has been found that the substrates of these enzymes are xylan, xyloglucan, dextran, cellulose and hemicellulose [ 35 , 37 , 38 ]. In the present study, we sought to investigate the function of SsGH5 in S. sclerotiorum .…”

Molecular insights into the oligosaccharide binding, recognition and hydrolysis by a fungal exo-β-(1,3)-glucanase

“…GH5 enzymes have enormous flexibility with respect to the type of substrate they can hydrolyse. As GH5 enzymes can hydrolyse both β- (1,4) as well as β- (1,3) linkages in sugars, such functional properties make them diverse with respect to their applications (23)(24)(25)(26)(27). There have been several reports on the utility of exo-β-(1,3)-glucanases towards various industrial and agricultural applications (28).…”