Preparation and properties of new biocatalysts for the degradation of nonstarch plant polysaccharides

Abstract

Recombinant strains of Penicillium verruculosum are developed that produce the homologous endoglucanase 2 (Eg2) and the P. canescens heterologous xylanase E (XylE). The recombinant strains are used to obtain new biocatalysts, i.e., enzyme preparations (EPs) that are substantially enriched with Eg2 and XylE. These preparations are highly active with respect to nonstarch plant polysaccharides (NPSes): cellulose, β-glucan, and xylan. The qualitative and quantitative compositions of the new EPs are studied by protein chromatography. It was shown that the EPs contained (in terms of total protein content) ~16–17% Eg2, 48–63% XylE, and 17–30% cellobiohydrolases, while the EP obtained using the recipient strain contained 1.4% Eg2, ~60% cellobiohydrolase and no XylE. The optimum pH values for cellulase (with respect to carboxymethylcellulose, CMC) and the xylanase activity of the EPs are 4.0 and 5.5, respectively. The EPs exhibit the abovementioned activities within a wide range of pH (3 to 7). The EPs exhibit CMC-ase and xylanase activities in the temperature range of 20–80°С with maxima at 60 and 70°C, respectively. The xylanase activity of the new EPs is virtually uninhibited by protein inhibitors of rye.