ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbiotechnology
This article is part of the Research TopicAdvanced Biocatalysts for Sustainable Chemical SynthesisView all articles
Growth-coupled selection of 5‑aminolevulinic acid synthetase mutants for 5‑aminolevulinic acid biosynthesis in Corynebacterium glutamicum
Provisionally accepted
- Xinyang Normal University, Xinyang, China
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Introduction: 5-Aminolevulinic acid (5-ALA) is a nonprotein amino acid with broad applications in agriculture, medicine, and the food industry. In recent years, substantial efforts have been devoted to enhancing its biosynthesis. The catalytic activity of 5-aminolevulinic acid synthase (ALAS) is a critical determinant of production efficiency. Methods: In this study, a growth-coupled selection strategy was developed to improve ALAS from Rhodobacter capsulatus SB1003 using random and site-specific mutagenesis. The derived ALAS mutant was then introduced into the GRAS-certified producer Corynebacterium glutamicum, followed by fermentation optimization. Results: The enzymatic activity of the best mutant, D4,7,18, increased by 67.41%, leading to 1.18-fold higher 5-ALA accumulation than that of the wild type. Enzymatic analysis suggested that the enhanced activity of D4,7,18 was partly attributable to stronger PLP binding and a lower Km for glycine. During fermentation optimization, the results underscored the crucial roles of dissolved oxygen, Fe2+ and glycine supplementation. Ultimately, 8.72 g/L of 5-ALA was produced within 60 hours, with minimal accumulation of organic acid byproducts. Conclusion: The growth-coupled selection strategy demonstrated in this study offers a promising approach for optimizing other enzymes and metabolic pathways, provided that an appropriate selection strain and screening conditions are employed.
Keywords: 5‑aminolevulinic acid, 5‑aminolevulinic acid synthetase, Growth-coupled selection, Fermentation optimization, biosynthesis
Received: 02 Oct 2025; Accepted: 31 Oct 2025.
Copyright: © 2025 Yang, Fan, Zhao, Yu, Yan, Han, Song and Gong. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: An-dong Gong, gongad@xynu.edu.cn
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