Isolation, cloning and molecular characterization of a thermotolerant xylanase from Streptomyces sp. THW31

  • Thayat Sriyapai
  • Peechapack Somyoonsap
  • Supatra Areekit
  • Paisarn Khawsak
  • Arda Pakpitcharoen
  • Kosum Chansiri

Abstract

A xylan-degrading Streptomyces sp. THW31 was isolated from rubbish compost in Thailand. Analysis of a genomic library of nucleotide sequences from Streptomyces sp. THW31 revealed that the complete open reading frame (ORF) of xylanase (xlnW31) was 999 bp, and this gene encoded a member of the glycosyl hydrolase family 11. Sequence homology of the predicted amino acid sequence encoded by xlnW31 demonstrated that the enzyme consists of a signal peptide, catalytic and substrate-binding domains. The XlnW31 enzyme shared the highest identity (90%) to a xylanase family 11 member from Streptomyces lividans TK24. Cloning and expression of xlnW31 in Escherichia coli resulted in the production and purification of a 31.0 kDa enzyme. Purified XlnW31 show the highest activity at pH 6.0 and at a temperature 65 to 70°C. Enzyme stability tests indicated that XlnW31 retained its activity over a broad pH range (5.0 to 11.0) and at temperatures reaching 60°C for 2 h. Purified XlnW31 also exhibited endo-1,4-β -xylanase activity using xylan as a substrate and bound to insoluble xylan. Hydrolysis of xylan by the xylanase yielded xylobiose as the principal product.

Keywords: Gene expression, hemicellulase, Streptomyces, xylan, xylanase

African Journal of Biotechnology Vol. 12(4), pp. 427-437

Author Biographies

Thayat Sriyapai
Faculty of Environmental Culture and Ecotourism, Srinakharinwirot University, Bangkok 10110, Thailand
Peechapack Somyoonsap
Department of Biology, Faculty of Sciences, Srinakharinwirot University, Bangkok 10110, Thailand
Supatra Areekit
Innovative Learning Center, Srinakharinwirot University, Bangkok 10110, Thailand
Paisarn Khawsak
Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok 10110, Thailand
Arda Pakpitcharoen
Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok 10110, Thailand
Kosum Chansiri
Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok 10110, Thailand
Published
2015-11-29
Section
Articles

Journal Identifiers


eISSN: 1684-5315