Cloning, expression and applicability of thermo-alkali-stable xylanase of Geobacillus thermoleovorans in generating xylooligosaccharides from agro-residues.
A xylanase gene (xyl-gt) of 1.224 kbp was cloned from the extremely thermophilic bacterium Geobacillus thermoleovorans that encodes a protein containing 408 amino acid residues. Eight conserved regions (signature sequences) of GH family 10 xylanases have been found in the xylanase. When the xylanase gene was cloned and expressed in Escherichia coli BL21 (DE3), the recombinant strain produced xylanase titer of 270 U mg(-1) which is 27-fold higher than the wild strain. It is optimally active at 80°C and pH 8.5 with a high thermostability over broad range of pH (6-12) and temperature (40-100°C). The end products of the hydrolysis of birch wood xylan and agro-residues included xylobiose, xylotriose, xylotetraose and xylopentaose. The xylanase of G. thermoleovorans is one of the rare xylanases that exhibits thermo-alkali-stability, and thus, it is a suitable candidate for pre-bleaching of paper pulps and generating xylooligosaccharides from agro-residues for use as prebiotics.
Department of Microbiology, University of Delhi South Campus, New Delhi 110 021, India.
Digvijay
D
Verma
T
T
Satyanarayana
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D056506:Geobacillus / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D009844:Oligosaccharides; D011994:Recombinant Proteins; D043364:Endo-1,4-beta Xylanases