Characterization, cloning and functional expression of novel xylanase from Thermomyces lanuginosus SS-8 isolated from self-heating plant wreckage material

Abstract

Extracellular cellulase free xylanase from Thermomyces lanuginosus sp. SS-8, isolated from self heating plant wreckage material was identified as β-1,4-endo-xylanase precursor, a monomer of 21.3kDa with no carbohydrate residue. This xylanase retained 80% activity at 60°C for 96h, was active at a wide pH range of 3-11 and uniquely hydrolyzed xylan to xylose without production of xylo-oligosaccharides. Gene xynSS8 encoding xylanase from T. lanuginosus SS-8 was cloned and functionally expressed in Escherichia coli XL1 Blue using pTZ57R/T plasmid and xynSS8/pQE-9 expression vector construct respectively. Gene xynSS8 was of 777bp and deduced amino acid sequence was a mature xylanase of 258 amino acids. XynSS8 has extra 33 amino acids compared to its nearest homolog and was thermo-alkali tolerant as that of native protein. The xylanase could degrade pulp and release substantial chromophoric materials and lignin derived compounds indicating its effective utility in pulp bleaching. Novel characteristics of the enzyme may contribute to its wide industrial usage. This is first report of cloning and functional expression of the novel xylanase from T. lanuginosus SS-8.