A cellulolytic Hypocrea strain isolated from South American brave straw produces a modular xylanase.
Author
Summary, in English
Cellulase-producing fungi from the Andean regions in Bolivia, an ecosystem characterized as an extreme arid highland, were studied. Thirty-two isolates were screened for presence of cellulase activity using carboxymethyl cellulose (CMC) as carbon source, and activity was confirmed using a filter paper assay. One isolate, denoted as BLT1C was selected from this screening, and sequence analysis of the internal transcribed spacer (ITS) classified the strain as Hypocrea lixii. The secretome of BLT1C showed high xylanase activity (compared to that of two reference Trichoderma reesei strains) when cultivated using brave straw, an abundant native grass from the area, as carbon source. SDS-PAGE analysis revealed three main protein-bands (18, 32 and 65kDa) and in-gel digestion and mass spectrometry combined with activity analysis showed that these proteins were active xylanases with molecular masses corresponding to (I) a single glycoside hydrolase family 11 catalytic module (18kDa), and (II, III) modular enzymes, with the GH11 catalytic domain connected to a module of unknown function (32kDa) or putatively connected to a GH7 catalytic module (65kDa). The N-terminal sequence of the 65kDa xylanase did not show significant sequence similarities to deposited sequences. The collected data on xylanase activity, molecular mass, GH11-sequence conservation, combined with lack of sequence similarities in the N-terminus show that the 65kDa band corresponds to a novel modular xylanase.
Department/s
Publishing year
2012
Language
English
Pages
215-223
Publication/Series
Carbohydrate Research
Volume
356
Document type
Journal article
Publisher
Elsevier
Topic
- Industrial Biotechnology
- Chemical Engineering
Status
Published
ISBN/ISSN/Other
- ISSN: 1873-426X