AUTHOR=Lu Nan , Zhang Chenglin , Zhang Wenjie , Xu Haoran , Li Yuhong , Wei Minhua , Meng Jing , Meng Yan , Wang Junzhe , Chen Ning 

TITLE=A Myo-Inositol-Inducible Expression System for Corynebacterium glutamicum and Its Application

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.746322

DOI=10.3389/fbioe.2021.746322

ISSN=2296-4185

ABSTRACT=<p><italic>Corynebacterium glutamicum</italic> is one of the important industrial microorganisms for production of amino acids and other value-added compounds. Most expression vectors used in <italic>C. glutamicum</italic> are based on inducible promoter (P<sub><italic>tac</italic></sub> or P<sub><italic>trc</italic></sub>) activated by isopropyl-β-D-thiogalactopyranoside (IPTG). However, these vectors seem unsuitable for large-scale industrial production due to the high cost and toxicity of IPTG. Myo-inositol is an ideal inducer because of its non-toxicity and lower price. In this study, a myo-inositol-inducible expression vector pMI-4, derived from the expression vector pXMJ19, was constructed. Besides the original chloramphenicol resistance gene <italic>cat</italic>, multiple cloning sites, and <italic>rrnB</italic> terminator, the pMI-4 (6,643 bp) contains the <italic>iolR</italic><sup><italic>q</italic></sup> cassette and the myo-inositol-inducible promoter P<sub><italic>iolT1</italic></sub>. The pMI-4 could stably replicate in the <italic>C. glutamicum</italic> host. Meanwhile, the non-myo-inositol degradation host strain <italic>C. glutamicum</italic>Δ<italic>iolG</italic>Δ<italic>oxiC</italic>Δ<italic>oxiD</italic>Δ<italic>oxiE</italic> for maintaining the pMI-4 was developed. Overexpression of <italic>hemA</italic><sup><italic>M</italic></sup> and <italic>hemL</italic> using pMI-4 resulted in a significant accumulation of 5-aminolevulinic acid, indicating its potential application in metabolic engineering and industrial fermentation.</p>