title: Alkaline xylanases from Bacillus mojavensis A21: production and generation of xylooligosaccharides.
abstract: Medium composition and culture conditions for the xylanases production by Bacillus mojavensis A21 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of enzyme production and Box-Behnken design used to optimize the value of the four significant variables: barley bran, NaCl, agitation, and cultivation time. The optimal conditions for higher production of xylanases were barley bran 18.66 g/l, NaCl 1.04 g/l, speed of agitation 176 rpm and cultivation time 34.08 h. Under these conditions, the xylanase experimental yield (7.45 U/ml) closely matched the yield predicted by the statistical model (7.23 U/ml) with R² = 0.98. The medium optimization resulted in a 6.83-fold increase in xylanase production compared to that of the initial medium. Best xylanase activity was observed at the temperature of 50 °C and at pH 8.0. The enzyme retained more 96% of its activity after 24 h at pH ranges from 7.0 to 90.0. The enzyme preserved more 80% of its initial activity after 60 min of pre-incubation from 30 °C to 60 °C. The main hydrolysis products yielded from corncob extracted xylan were xylobiose and xylotriose, suggesting the good potential of strain A21 in xylooligosaccharides production.
authors: Laboratoire de Génie Enzymatique et de Microbiologie-Ecole Nationale d'Ingénieurs de Sfax, B.P. 1173, 3038 Sfax, Tunisia. anissa_ing@yahoo.fr
authors: Anissa
authors: A
authors: Haddar
authors: Dorra
authors: D
authors: Driss
authors: Fakher
authors: F
authors: Frikha
authors: Semia
authors: S
authors: Ellouz-Chaabouni
authors: Moncef
authors: M
authors: Nasri
mesh_terms: D001407:Bacillus / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D049109:Cell Proliferation; D004591:Electrophoresis, Polyacrylamide Gel; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D004795:Enzyme Stability; D005285:Fermentation; D005965:Glucuronates / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009844:Oligosaccharides / Q000096:biosynthesis*; D014990:Xylans / Q000378:metabolism; D003313:Zea mays / Q000737:chemistry
chemical_list: D005965:Glucuronates; D009844:Oligosaccharides; D014990:Xylans; C570991:xylooligosaccharide; D043364:Endo-1,4-beta Xylanases