Department of Fermentation Science and Technology, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
Department of Biochemistry and Applied Bioscience, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadainishi, Miyazaki-shi, Miyazaki 889-2192, Japan.
J Biosci Bioeng. 2023 Sep;136(3):198-204. doi: 10.1016/j.jbiosc.2023.07.003. Epub 2023 Jul 22.
Clostridium saccharoperbutylacetonicum strain N1-4 (ATCC13564) is a butanol-producing strain suitable for application to butanol production from cellulosic materials by co-culture with cellulolytic and thermophilic species, such as Hungateiclostridium thermocellum (synonym: Clostridium thermocellum). The optimal temperature for butanol production by strain N1-4 is 30 °C, and the strain is sensitive to a high culture temperature of 37 °C. Given that spore formation is observed at high frequency when strain N1-4 is cultivated at 37 °C, we assumed in a previous study that the initiation of sporulation is related to a decrease in butanol production. Therefore, to investigate the relationship between butanol production and spore formation, we generated strain N1-4 isolates in which genes related to spore formation were disrupted. The sporulation-related gene disruptants of spo0A, sigE, sigG, and sigK lost the ability to produce heat-resistant spores, irrespective of the culture temperature. Among the gene disruptants produced, only the spo0A disruptant lost butanol-producing ability when cultivated at 30 °C. Interestingly, the sigE disruptant maintained butanol productivity similar to that observed at 30 °C, even when cultivated at 37 °C. In addition, the sigE disruptant successfully produced butanol from Avicel cellulose by co-culture with H. thermocellum at a fermentation temperature of 37 °C.
丙酮丁醇梭菌 N1-4 株（ATCC13564）是一种生产丁醇的菌株，适合与纤维素分解和嗜热物种（如纤维梭菌（同义词：热纤维梭菌））共培养，从纤维素材料生产丁醇。N1-4 菌株生产丁醇的最佳温度为 30°C，该菌株对 37°C 的高温培养敏感。鉴于在 37°C 培养时 N1-4 菌株频繁形成孢子，我们之前的研究假设孢子形成的开始与丁醇产量的下降有关。因此，为了研究丁醇生产与孢子形成之间的关系，我们生成了 N1-4 菌株的分离株，其中与孢子形成相关的基因被破坏。spo0A、sigE、sigG 和 sigK 等与孢子形成相关的基因破坏体，无论培养温度如何，均失去产生耐热孢子的能力。在所产生的基因破坏体中，只有 spo0A 破坏体在 30°C 培养时丧失了生产丁醇的能力。有趣的是，即使在 37°C 培养时，sigE 破坏体仍保持与 30°C 时相似的丁醇生产能力。此外，sigE 破坏体在 37°C 的发酵温度下通过与 H. thermocellum 共培养，成功地从 Avicel 纤维素生产丁醇。
