AUTHOR=Basit Abdul , Liu Junquan , Miao Ting , Zheng Fengzhen , Rahim Kashif , Lou Huiqiang , Jiang Wei 

TITLE=Characterization of Two Endo-β-1, 4-Xylanases from Myceliophthora thermophila and Their Saccharification Efficiencies, Synergistic with Commercial Cellulase

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00233

DOI=10.3389/fmicb.2018.00233

ISSN=1664-302X

ABSTRACT=<p>The xylanases with high specific activity and resistance to harsh conditions are of high practical value for biomass utilization. In the present study, two new GH11 xylanase genes, <italic>MYCTH_56237</italic> and <italic>MYCTH_49824</italic>, have been cloned from thermophilic fungus <italic>Myceliophthora thermophila</italic> and expressed in <italic>Pichia pastoris</italic>. The specific activities of purified xylanases reach approximately 1,533.7 and 1,412.5 U/mg, respectively. Based on multiple template-based homology modeling, the structures of their catalytic domains are predicted. Enzyme activity was more effective in 7.5 L fermentor, yielding 2,010.4 and 2,004.2 U/mL, respectively. Both enzymes exhibit optimal activity at 60°C with pH of 6.0 and 7.0, respectively. Their activities are not affected by EDTA and an array of metal ions. The kinetic constants have been determined for MYCTH_56237 (<italic>K</italic><sub><italic>m</italic></sub> = 8.80 mg/mL, <italic>V</italic><sub><italic>max</italic></sub> = 2,380 U/mg) and MYCTH_49824 (<italic>K</italic><sub><italic>m</italic></sub> = 5.67 mg/mL, <italic>V</italic><sub><italic>max</italic></sub> = 1,750 U/mg). More importantly, both xylanases significantly cooperate with the commercial cellulase Celluclast 1.5 L in terms of the saccharification efficiency. All these biochemical properties of the xylanases offer practical potential for future applications.</p>