Identification and characterization of a novel thermostable xylanase from camel rumen metagenome

Metagenomics has emerged to isolate novel enzymes from the uncultured microbiota in the environment. In this study, the metagenomic data obtained from camel rumen was considered as the potential source of microbial xylanase enzymes with proper activity in extreme conditions. The metagenomic data were assembled and contigs were used for in-silico identification of candidate thermostable enzyme. A novel thermostable xylanase enzyme, named PersiXyn1, with 1146 bp full-length gene which encodes a 381 amino acid protein was identified. Using the DNA template extracted from camel rumen metagenomic samples, the candidate enzyme genes were cloned and expressed in proper E. coli strains. The phylogenetic analysis showed the evolutionary position of PersiXynl among the known thermostable xylanases. The results of the CD analysis and determining the secondary structure of the enzyme, confirmed the presence of a high percentage of beta-sheets as an important characteristic of thermophilic xylanases. The PersiXynl was active at a broad range of pH (6-11) and temperature (25-90 degrees C). The optimum pH and temperature were 8 and 40 degrees C respectively, and the enzyme maintained 80% of its maximum activity in the pH 8 and temperature 40 degrees C for 1 h. The Scanning electron microscope (SEM) micrograph of enzyme treated pulp clearly showed that the effective use of enzymes in fiber separation may reduce the cost of carton paper production. The novelty of this enzyme lies in the fact that it is highly active and stable in a broad range of pH and temperature. This study highlights the potential importance of camel microbiome for discovering novel thermostable enzymes with applications in agriculture and industries. (C) 2018 Published by Elsevier B.V.