Paenibacillus sp. A59 GH10 and GH11 Extracellular Endoxylanases: Application in Biomass Bioconversion

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Paenibacillus sp. A59 GH10 and GH11 Extracellular Endoxylanases: Application in Biomass Bioconversion Silvina Ghio 1 & Ornella Ontañon 2,3 & Florencia E. Piccinni 2,3 & Rubén Marrero Díaz de Villegas 2 & Paola Talia 2,3 & Daniel H. Grasso 1,4 & Eleonora Campos 2,3

# Springer Science+Business Media, LLC, part of Springer Nature 2017

Abstract The cost-efficient degradation of xylan to fermentable sugars is of particular interest in second generation bioethanol production, feed, food, and pulp and paper industries. Multiple potentially secreted enzymes involved in polysaccharide deconstruction are encoded in the genome of Paenibacillus sp. A59, a xylanolytic soil bacterium, such as three endoxylanases, seven GH43 β-xylosidases, and two GH30 glucuronoxylanases. In secretome analysis of xylan cultures, ten glycoside hydrolases were identified, including the three predicted endoxylanases, confirming their active role. The two uni-modular xylanases, a 32-KDa GH10 and a 20-KDa GH11, were recombinantly expressed and their activity on xylan was confirmed (106 and 85 IU/mg, respectively), with differences in their activity pattern. Both endoxylanases released mainly xylobiose (X2) and xylotriose (X3) from xylan and pre-treated biomasses (wheat straw, barley straw, and sweet corn cob), although only rGH10XynA released xylose (X1). rGH10XynA presented optimal conditions at pH 6, with thermal stability at 45–50 °C, while rGH11XynB showed activity in a wider range of pH, from 5 to 9, and was thermostable only at 45 °C. Moreover, GH11XynB presented sigmoidal kinetics on xylan, indicating possible cooperative binding, which was further supported by the structural model. This study provides a detailed analysis of the complete set of carbohydrate-active enzymes encoded in Paenibacillus sp. A59 genome and those effectively implicated in hemicellulose hydrolysis, contributing to understanding the mechanisms necessary for the bioconversion of this polysaccharide. Moreover, the two main free secreted xylanases, rGH10XynA and rGH11XynB, were fully characterized, supporting their potential application in industrial bioprocesses on lignocellulosic biomass. Keywords Paenibacillus . Endoxylanases . GH10 . GH11 . Pre-treated biomass

Introduction Increasing the need for renewable fuels highlights the requirement of suitable technology development from sustainable Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12155-017-9887-7) contains supplementary material, which is available to authorized users. * Eleonora Campos [email protected]; [email protected] 1

Instituto de Suelos, CIRN, Instituto Nacional de Tecnología Agropecuaria (INTA), Hurlingham, Buenos Aires, Argentina

2

Instituto de Biotecnología, CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Los Reseros y N. Repetto, Hurlingham B1686, Buenos Aires, Argentina

3

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina

4

Departamento de Ciencia y Tecn