The redox-sensing transcriptional repressor Rex is important for regulating the products distribution in Thermoanaerobacterium aotearoense SCUT27
- 1 June 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in Applied Microbiology and Biotechnology
- Vol. 104 (12), 5605-5617
- https://doi.org/10.1007/s00253-020-10554-7
Abstract
The redox-sensing transcriptional repressor Rex (Rex) displayed diverse functions in different microbial species. Nowadays, only part function of rex has been verified in vitro and alcohol dehydrogenase gene (adhE) as the target of Rex has been widely reported. In this study, rex was knocked out in Thermoanaerobacterium aotearoense SCUT27 (GDMCC 60765) and the carbon metabolic distribution analysis was performed. Results showed that the ethanol yield (mol product/mol carbon) of SCUT27(Delta rex) had increased by 75.00-90.91%, cell growth improved by 27.27-36.36%, and acetic acid and lactic acid decreased by 58.33-61.54% accompanied with the yield of hydrogen decreased by 46.15-58.35% within different carbon sources. The ability of sugar consumption of SCUT27(Delta rex) had improved about 74.19-130.55% with the improvement of total ATP concentration and the cofactors NADH and NAD(+) concentrations. In addition, the specific activities of alcohol dehydrogenase of SCUT27(Delta rex) with NADH and NADPH as cofactors were improved by 119.26-140.28% and 35.66-47.69%, respectively. After ldh was further knocked out in SCUT27(Delta rex), SCUT27(Delta ldh Delta rex) showed higher ethanol production and yield when various carbon resources were used as substrates (including glucose, xylose, glucose/xylose mixture and three kinds of lignocellulosic hydrolysates). This study confirms that Rex is an important regulator for determining products distribution in SCUT27 and deletion of rex and ldh is a promising strategy for enhanced ethanol production.Keywords
Funding Information
- National Natural Science Foundation of China (21878103)
- National Natural Science Foundation of China (21676098, 21808069)
- Natural Science Foundation of Guangdong Province (2018A030310368)
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