Biotechnology and Bioprocess Engineering 2019; 24(3): 544-551  
A Novel Cold-adapted Endoglucanase (M6A) from Microbacterium kitamiense S12 Isolated from Qinghai-Tibetan Plateau
Ling Lin*, Na Qin, and Linyan Guan
Institute of Molecular Biology and Biotechnology and the Research Center of Life Omics and Health, Provincial Key Laboratory of the Conservation and Exploitation of Biological Resources, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China
Correspondence to: Ling Lin
Tel: +86-553-3869297; Fax: +86-553-3869571
E-mail: linling8@ahnu.edu.cn
Received: January 8, 2019; Revised: February 10, 2019; Accepted: February 22, 2019; Published online: June 30, 2019.
© The Korean Society for Biotechnology and Bioengineering. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The gene M6A coding a novel cold-adapt endoglucanase was cloned from Microbacterium kitamiense Sa12 isolated from a wasteland in Saga, Qinghai-Tibetan Plateau. The deduced protein sequence encoded a 411-residue polypeptide sharing similar identities with glycosyl hydrolase family 6 enzymes. The recombinant M6A displayed maximum hydrolysis activity of 1.51 U/mg toward soluble cellulose substrate, CMC at 35°C and pH 5.0, and the Km and Vmax value were 2.12 mg/mL and 15.33 µmol/min*mg, respectively. Interestingly, M6A exhibited significant activity even at ice cold condition, showing 30-40% relative activity at 0-5°C, and had good tolerance to Li+, K+, NH4 +, Rb+, Ca2+, Mg2+, Zn2+, Mn2+, and Ni2+, expect divalent cation Cu2+ led to 30% residual activity. These properties might make M6A to be a promising candidate used in the psychrophilic industrial process and/or the volatile and thermosensitive manufacturing process.
Keywords: endoglucanase, Microbacterium kitamiense, cold-adapt, protein modeling


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