AUTHOR=Lin Hui , Zhao Jun , Zhang Qingqing , Cui Shixiu , Fan Zhiliang , Chen Hongge , Tian Chaoguang 

TITLE=Identification and Characterization of a Cellodextrin Transporter in Aspergillus niger

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00145

DOI=10.3389/fmicb.2020.00145

ISSN=1664-302X

ABSTRACT=<p><italic>Aspergillus niger</italic> produces a wide spectrum of extracellular polysaccharide hydrolases that hydrolyze cellulose into soluble glucose and cellodextrins. Transporters are essential for sugar uptake, yet it is not clear whether cellodextrin transporters exist in <italic>A. niger</italic>. Here, one cellulose inducible cellodextrin transporter CtA was identified in <italic>A. niger</italic> B2. It was found that CtA not only could transport cellobiose, but also cellotriose, cellotetraose, and cellopentaose. The yeast strain YPβG-CtA, expressing cellodextrin transporter CtA and an intracellular β-glucosidase, grew on cellobiose with the cell growth rate of 0.0830 ± 0.0113 h<sup>–1</sup> under aerobic condition. Furthermore, the engineered yeast could produce 1.1 g/L ethanol anaerobically on cellobiose in 2 days. The identification of CtA provides evidence that the cellodextrin uptake is a complementary strategy of cellulose utilization in <italic>A. niger</italic>, and the CtA could be a strong transporter candidate for constructing engineered cellodextrin-utilizing microorganisms.</p>