Improvement of bread making quality by supplementation with a recombinant xylanase produced by Pichia pastoris.

Kyoung Heon Kim,Carolina Cândida De Queiroz Brito Cunha,Luiz Artur Mendes Bataus,Aline Rodrigues Gama,Cirano José Ulhoa,Lorena Cardoso Cintra

doi:10.1371/journal.pone.0192996

Kyoung Heon Kim, Carolina Cândida De Queiroz Brito Cunha + Show 4 more

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https://doi.org/10.1371/journal.pone.0192996

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Abstract

Xylanases (EC 3.2.1.8) are hydrolytic enzymes, which randomly cleave the β-1,4-linked xylose residues from xylan. The synthetic gene xynBS27 from Streptomyces sp. S27 was successfully cloned and expressed in Pichia pastoris. The full-length gene consists of 729 bp and encodes 243 amino acids including 51 residues of a putative signal peptide. This enzyme was purified in two steps and was shown to have a molecular weight of 20 kDa. The purified r-XynBS27 was active against beechwood xylan and oat spelt xylan as expected for GH 11 family. The optimum pH and temperature values for the enzyme were 6.0 and 75 °C, respectively. The Km and Vmax were 12.38 mg/mL and 13.68 μmol min/mg, respectively. The r-XynBS27 showed high xylose tolerance and was inhibited by some metal ions and by SDS. r-XynBS27 was employed as an additive in the bread making process. A decrease in firmness, stiffness and consistency, and improvements in specific volume and reducing sugar content were recorded.

Highlights

Xylanases (EC 3.2.1.8) catalyze random endo-hydrolysis reactions of xylosidic links within the xylan chain to yield shorter xylooligosaccharides that are subsequently converted to xyloses by β-xylosidases (EC3.2.1.37) [1,2]
These enzymes have gained importance in biotechnology owing to their potential for application in various industries such as paper, animal feed, food manufacture, fermentation, and more recently, in biofuel production [3]
We describe the molecular cloning of a xylanase from Streptomyces sp

Summary

Introduction

Xylanases (EC 3.2.1.8) catalyze random endo-hydrolysis reactions of xylosidic links within the xylan chain to yield shorter xylooligosaccharides that are subsequently converted to xyloses by β-xylosidases (EC3.2.1.37) [1,2]. These enzymes have gained importance in biotechnology owing to their potential for application in various industries such as paper, animal feed, food manufacture, fermentation, and more recently, in biofuel production [3]. Actinomycetes are aerobic, gram-positive bacteria that have high GC content in their DNA They form extensive branching substrates, and aerial mycelia with numerous pigmentations, and are widely distributed in soil [6].

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