title: Production of xylooligosaccharides in SSF by Bacillus subtilis KCX006 producing β-xylosidase-free endo-xylanase and multiple xylan debranching enzymes.
abstract: Xylanase and xylooligosaccharides (XOS) are employed in food and feed industries. Though xylanase production from lignocellulosic materials (LCMs) by solid-state fermentation (SSF) is well known, the XOS formed during growth is not recovered due to its conversion to xylose by β-xylosidase and subsequent bacterial metabolism. A new strain, Bacillus subtilis KCX006, was exceptionally found to synthesize β-xylosidase-free endo-xylanase and multiple xylan debranching enzymes constitutively in the presence of LCMs. Absence of β-xylosidase resulted in accumulation of XOS during growth of KCX006 on LCMs. Therefore, this strain was used for simultaneous production of xylanase and XOS from agro-residues in solid-state fermentation (SSF). Partial purification of XOS from culture supernatant using activated charcoal followed by high-performance liquid chromatography (HPLC) analysis showed xylobiose to xylotetraose formed as the major products. Among various LCM substrates, wheat bran and groundnut oil-cake supported highest xylanase and XOS production at 2158 IU/gdw and 24.92 mg/gdw, respectively. The levels of xylanase and XOS were improved by 1.5-fold (3102 IU/gdw) and 1.9-fold (48 mg/gdw), respectively, by optimization of culture conditions.
authors.affiliation: a Department of Biotechnology , Indian Institute of Technology Madras , Chennai , India.
authors.forename: Shyam Sunder
authors.initials: SS
authors.lastname: Reddy
authors.affiliation: a Department of Biotechnology , Indian Institute of Technology Madras , Chennai , India.
authors.forename: Chandraraj
authors.initials: C
authors.lastname: Krishnan
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D005965:Glucuronates / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009844:Oligosaccharides / Q000378:metabolism*; D012988:Soil Microbiology; D013379:Substrate Specificity; D013696:Temperature; D014995:Xylosidases / Q000378:metabolism*
chemical_list: D005965:Glucuronates; D009844:Oligosaccharides; C570991:xylooligosaccharide; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase
keywords: Bacillus subtilis; lignocellulosic materials; xylooligosaccharides; β-xylosidase-free xylanase