Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech Mining of camel rumen metagenome to identify novel alkali-thermostable xylanase capable of enhancing the recalcitrant lignocellulosic biomass conversion Shohreh Ariaeenejad a , Morteza Maleki a , Elnaz Hosseini b , Kaveh Kavousi b , Ali A. Moosavi-Movahedi b , Ghasem Hosseini Salekdeh a, ⁎ a Department of Systems Biology, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research Education and Extension Organization (AREO), Karaj, Iran b Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran GRAPHICAL ABSTRACT ARTICLE INFO Keywords: Alkaline thermostable xylanase Metagenome Camel rumen Recalcitrant compounds ABSTRACT The aim of this study was to isolate and characterize novel alkali-thermostable xylanase genes from the mixed genome DNA of camel rumen metagenome. In this study, a five-stage computational screening procedure was utilized to find the primary candidate enzyme with superior properties from the camel rumen metagenome. This enzyme was subjected to cloning, purification, and structural and functional characterization. It showed high thermal stability, high activity in a broad range of pH (6–11) and temperature (30–90 °C) and effectivity in recalcitrant lignocellulosic biomass degradation. Our results demonstrated the power of in silico analysis to discover novel alkali-thermostable xylanases, effective for the bioconversion of lignocellulosic biomass. 1. Introduction Xylanases are hydrolytic enzymes which randomly cleave the β 1,4 backbone of the complex plant cell wall polysaccharide xylan. Many industries such as animal feed, pharmaceutical, paper and baking, and waste treatment are among those in which microbial xylanases have been applied. To meet the specific industry’s needs, an ideal xylanase should be equipped with specific properties, such as good pH and thermal stability, in addition to high specific activity. Plant lig- nocellulosic biomass is the most important feedstock for the sustainable https://doi.org/10.1016/j.biortech.2019.02.059 Received 30 November 2018; Received in revised form 9 February 2019; Accepted 11 February 2019 ⁎ Corresponding author at: Department of Systems Biology, Agricultural Biotechnology Research Institute of Iran (ABRII), P.O. Box: 31535-1897, Karaj, Iran. E-mail address: h_salekdeh@abrii.ac.ir (G.H. Salekdeh). Bioresource Technology 281 (2019) 343–350 Available online 12 February 2019 0960-8524/ © 2019 Elsevier Ltd. All rights reserved. T