College of Life Sciences, Huaibei Normal University, Huaibei, 235000, China.
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
Bioprocess Biosyst Eng. 2019 Apr;42(4):555-566. doi: 10.1007/s00449-018-2058-1. Epub 2019 Jan 12.
A glucose-glycerol mixed carbon source (MCS) can substantially reduce batch fermentation time and improve ε-poly-L-lysine (ε-PL) productivity, which was of great significance in industrial microbial fermentation. This study aims to disclose the physiological mechanism by transcriptome analyses. In the MCS, the enhancements of gene transcription mainly emerged in central carbon metabolism, L-lysine synthesis as well as cell respiration, and these results were subsequently proved by quantitative real-time PCR assay. Intracellular L-lysine determination and exhaust gas analysis further confirmed the huge precursor L-lysine pool and active cell respiration in the MCS. Interestingly, in the MCS, pls was remarkably up-regulated than those in single carbon sources without transcriptional improvement of HrdD, which indicated that the improved ε-PL productivity was supported by other regulators rather than hrdD. This study exposed the physiological basis of the improved ε-PL productivity in the MCS, which provided references for studies on other biochemicals production using multiple substrates.
葡萄糖-甘油混合碳源（MCS）可以显著缩短分批发酵时间，提高ε-聚赖氨酸（ε-PL）的产量，这在工业微生物发酵中具有重要意义。本研究旨在通过转录组分析揭示生理机制。在 MCS 中，基因转录的增强主要出现在中心碳代谢、L-赖氨酸合成以及细胞呼吸中，这些结果随后通过定量实时 PCR 检测得到证实。细胞内 L-赖氨酸测定和废气分析进一步证实了 MCS 中巨大的前体 L-赖氨酸库和活跃的细胞呼吸。有趣的是，在 MCS 中，pls 的表达显著上调，而 HrdD 的转录没有改善，这表明 ε-PL 产量的提高是由其他调节剂而非 hrdD 支持的。本研究揭示了 MCS 中提高 ε-PL 产量的生理基础，为使用多种底物生产其他生化物质的研究提供了参考。
