title: Production and characteristics of the recombinant extracellular bifunctional endoglucanase of the polyextremophilic bacterium Bacillus halodurans and its applicability in saccharifying agro-residues.
abstract: The recombinant alkalistable and moderately thermostable bifunctional endoglucanase gene (BhCell-Xyl) of polyextremophilic bacterium Bacillus halodurans TSLV1 has been expressed in Pichia pastoris under constitutive GAP as well as inducible AOX promoters. A higher titre of recombinant BhCell-Xyl was attained after induction (4.8 U mL-1) as compared to that of the constitutive production (2.1 U mL-1). The recombinant P. pastoris strains integrated two copies of BhCell-Xyl under AOX and GAP promoters. The pure recombinant BhCell-Xyl is a glycoprotein of 66 kDa, which is optimally active at 60 °C and pH 6.0 and 8.0. Glycosylated BhCell-Xyl exhibits higher thermostability than that of the native enzyme. The analysis of amino acids of BhCell-Xyl revealed that multiple factors are responsible for its thermostability. Kinetics and in silico analysis of the enzyme suggested that BhCell-Xyl has one active site for both endocellulase and endoxylanase activities. The BhCell-Xyl possesses a carbohydrate binding domain and saccharifies lignocellulosic agro-residues to xylo-oligosaccharides and cello-oligosaccharides, suggesting its potential application in generating fermentable sugars from renewable agro-residues for biofuel and fine chemical industries.
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110 021, India.
authors.forename: Ranjitha R
authors.initials: RR
authors.lastname: Prabhu
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110 021, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Parashar
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110 021, India. tsnarayana@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Satyanarayana
mesh_terms: D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002480:Cellulase / Q000737:chemistry* / Q000235:genetics; D004795:Enzyme Stability; D005965:Glucuronates / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008031:Lignin / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D005965:Glucuronates; D009844:Oligosaccharides; D011994:Recombinant Proteins; C570991:xylooligosaccharide; C036909:lignocellulose; D008031:Lignin; D002480:Cellulase
keywords: Bacillus halodurans; Bifunctional enzyme; Endoglucanase; P. pastoris; Polyextremophilic