Production of a thermostable and alkali resistant endoxylanase by Bacillus subtilis DFR40 and its application for preparation of prebiotic xylooligosaccharides
2018
Xavier, Janifer Raj | Ramana, Karna Venkata | Sharma, Rakesh Kumar
Xylanases produced by microorganisms hydrolyze xylan, into xylose or xylooligosaccharides (XOS). Xylan is an abundant noncellulosic polysaccharide found in the plant biomass. The enzyme is of great practical importance for the conversion of xylan containing agricultural residues into XOS for use as prebiotics. A Bacillus subtilis strain DFR40 a generally recognized as safe (GRAS) organism was found to produce extracellular xylanase in a growth medium containing wheat bran, mineral salts, peptone, and yeast extract at pH 7.0. The optimum activity of the enzyme was around 100°C and pH 9.0 with stability over a broad range of pH (7.0–12.0) displaying enzyme stability of more than 70% even after pre‐incubation at 55–85°C for 30 min. The enzyme hydrolyzed wheat bran into short chain XOS as revealed by TLC, HPLC, FT‐IR, and NMR analysis. PRACTICAL APPLICATIONS: The thermostable and alkali resistant characteristics of extracted xylanase along with ability to hydrolyze wheat bran for the production of xylooligosaccharides (XOS), for use as prebiotic ingredients in food, are relevant in the present health conscious worldwide scenario. XOS are emerging class of prebiotics with thermal resistance up to 100°C, and are suitable for incorporating into thermally processed food products with extended shelf life. The XOS preparation was also found suitable suggesting the prebiotic nature of XOS on known probiotic bacterial strains. The study also indicates a valuable application for wheat bran, a cheap agro residue for further cost effective scale up of XOS production. The xylanase produced is of significance as the producing bacterium is a GRAS organism for further scale‐up of the processes of enzyme and XOS production.
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