Recombinant Xylanase from Bacillus tequilensis BT21: Biochemical Characterisation and Its Application in the Production of Xylobiose from Agricultural Residues.

Rakhee Khandeparker,Ujwala Amberkar,Pankaj Parab

doi:10.17113/ftb.55.02.17.4896

Rakhee Khandeparker, Ujwala Amberkar + Show 1 more

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https://doi.org/10.17113/ftb.55.02.17.4896

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Abstract

Bacterial strain Bacillus tequilensis BT21 isolated from marine sediments was found to produce extracellular xylanase. The xynBT21 gene encoding xylanase enzyme was cloned and expressed in Escherichia coli. The gene encoded a protein consisting of 213 amino acid residues with calculated molecular mass of 23.3 kDa. Puriﬁed recombinant xylanase had optimum activity at 60 °C and pH=6. The enzyme was highly stable in alkaline pH, at pH=7 it remained 100% active for 24 h, while its activity increased at pH=8 and 9 during incubation. B. tequilensis BT21 xylanase had alkaline pI of 9.4 and belongs to glycosyl hydrolase family 11. The mode of action of XynBT21 on beechwood xylan and xylooligosaccharides was studied. It hydrolysed xylooligosaccharides and beechwood xylan yielding mainly xylobiose (X2) with a small amount of xylose (X1), indicating that XynBT21 was probably an endo-acting xylanase. Enzymatic hydrolysis using wheat bran as a substrate revealed that xylanase reported here has the potential to produce xylobiose from wheat bran. Xylooligosaccharides, especially xylobiose, have strong bifidogenic properties and are increasingly used as a prebiotic. This is the ﬁrst report that describes this novel xylanase enzyme from marine B. tequilensis BT21 used for the release of xylobiose from wheat bran.

Highlights

Xylan, the most abundant hemicellulose, consists of β-1,4-linked xylose residues in the backbone to which O-acetyl, α-l-arabinofuranosyl, d-α-glucuronic and phenolic acid residues are attached
We report the characterisation of xylanase from a marine bacterium Bacillus tequilensis BT21 and propose its efficacy in the nutraceutical industry
Biochemical analysis of B. tequilensis BT21 isolate revealed that it belonged to the Gram-positive group, its cells are short motile rods, oxidase positive and catalase positive

Summary

Introduction

The most abundant hemicellulose, consists of β-1,4-linked xylose residues in the backbone to which O-acetyl, α-l-arabinofuranosyl, d-α-glucuronic and phenolic acid residues are attached. Endoxylanases degrade β-1,4-xylan randomly, yielding a chain of linear and branched oligosaccharide fragments. Regarding the amino acid sequence similarities, xylanases are mostly classified into families 10 and 11 of the glycoside hydrolases. Industrial process conditions are harsh due to extremes of pH, temperature, inhibitors, etc. Strong enzymes able to withstand such conditions are recommended for these processes. Most of the reported xylanases do not meet such criteria, enzymes that satisfy these requirements need to be found [4,5]. The marine environment is highly complex and dynamic with high salinity, high pressure, low or high temperature and unique light conditions, which may explain the significant variations in the enzymes pro-

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