College of Biological and Agricultural Engineering, Jilin University, Changchun, 130022, China.
Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
Microb Cell Fact. 2024 Oct 29;23(1):294. doi: 10.1186/s12934-024-02568-x.
High-temperature fermentation technology is promising in improving fermentation speed and product quality, and thereby widely used in various fields such as food, pharmaceuticals, and biofuels. However, extreme temperature conditions can disrupt cell membrane structures and interfere with the functionality of biological macromolecules (e.g. proteins and RNA), exerting detrimental effects on cellular viability and fermentation capability.
Herein, a microbial thermotolerance improvement strategy was developed based on adaptive laboratory evolution (ALE) for efficient high-temperature fermentation. Employing this strategy, we have successfully obtained Corynebacterium glutamicum strains with superior resistance to high temperatures. Specifically, the genome analysis indicated that the evolved strains harbored 13 missense genetic mutations and 3 same-sense genetic mutations compared to the non-evolved parent strain. Besides, reverse transcription quantitative PCR analysis (RT qPCR) of the hrcA-L119P mutant demonstrated that both groEL genes were upregulated under 42 °C, which enabled the construction of robust strains with improved heat tolerance. Furthermore, a significant increase in FAS-IA and FAS-IB expression of the fasR-L102F strain was proved to play a key role in protecting cells against heat stress.
This work systematically reveals the thermotolerance mechanisms of Corynebacterium glutamicum and opens a new avenue for revolutionizing the design of cell factories to boost fermentation efficiency.
高温发酵技术在提高发酵速度和产品质量方面具有广阔的应用前景，广泛应用于食品、制药和生物燃料等各个领域。然而，极端的温度条件会破坏细胞膜结构，并干扰生物大分子（如蛋白质和 RNA）的功能，对细胞活力和发酵能力产生有害影响。
本文基于适应性实验室进化（ALE）开发了一种微生物耐热性改善策略，用于高效的高温发酵。采用该策略，我们成功获得了具有较高耐高温能力的谷氨酸棒杆菌菌株。具体而言，基因组分析表明，与非进化亲本菌株相比，进化菌株具有 13 个错义基因突变和 3 个同义基因突变。此外，对 hrcA-L119P 突变体的反转录定量 PCR 分析（RT-qPCR）表明，在 42°C 下，两个 groEL 基因均上调，从而构建了具有耐热性提高的稳健菌株。此外，fasR-L102F 菌株 fasR-IA 和 fasR-IB 表达的显著增加被证明在保护细胞免受热应激方面发挥了关键作用。
本研究系统地揭示了谷氨酸棒杆菌的耐热机制，为细胞工厂的设计带来了革命性的变化，以提高发酵效率。
