2Resource Center for Molecular and Cell Technologies and “Centre Biobank”, St. Petersburg State University, Stary Peterhof, 198504 St. Petersburg, Russia
3Orekhovich Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, 119121 Moscow, Russia
4Peter the Great St. Petersburg Polytechnic University, Department of Medical Physics, 194021 St. Petersburg, Russia
* To whom correspondence should be addressed.
Received December 15, 2017; Revision received July 5, 2018
Complete enzymatic degradation of plant polysaccharides is a result of combined action of various carbohydrate-active enzymes (CAZymes). In this paper, we demonstrate the potential of the filamentous fungus Scytalidium candidum 3C for processing of plant biomass. Structural annotation of the improved assembly of S. candidum 3C genome and functional annotation of CAZymes revealed putative gene sequences encoding such proteins. A total of 190 CAZyme-encoding genes were identified, including 104 glycoside hydrolases, 52 glycosyltransferases, 28 oxidative enzymes, and 6 carbohydrate esterases. In addition, 14 carbohydrate-binding modules were found. Glycoside hydrolases secreted during the growth of S. candidum 3C in three media were analyzed with a variety of substrates. Mass spectrometry analysis of the fungal culture liquid revealed the presence of peptides identical to 36 glycoside hydrolases, three proteins without known enzymatic function belonging to the same group of families, and 11 oxidative enzymes. The activity of endo-hemicellulases was determined using specially synthesized substrates in which the glycosidic bond between monosaccharide residues was replaced by a thio-linkage. During analysis of the CAZyme profile of S. candidum 3C, four β-xylanases from the GH10 family and two β-glucanases from the GH7 and GH55 families were detected, partially purified, and identified.
KEY WORDS: CAZymes, lignocellulases, glycoside hydrolases, para-nitrophenyl β-S-D-glycobiosides