ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbial Physiology and Metabolism
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1578160
Combination of SPH and SP80 extend the lifespan of Bacillus subtilis natto for enhancing industrial menaquinone-7 biosynthesis
Provisionally accepted
Yan Liu*
Liu-Xiu HuXu-Li GaoWei TaoYu Chen
Chuan-Chao WuHui-Min ZhangRu-Meng HanYu-Qi LiHong-Ping Zhou- Anhui Polytechnic University, Wuhu, China
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
Menaquinone-7 (MK-7) production from renewable feedstocks by Bacillus subtilis natto provided a promising avenue towards sustainability. However, the yield of MK-7 was often limited by the poor microbial cell viability. Here, a novel fermentation strategy based on prolongation the lifespan of B. subtilis natto was investigated to enhance MK-7 biosynthesis. Results showed that the combination of soy protein hydrolysate (SPH) and Span 80 (SP80) increased intracellular and extracellular MK-7 yield by 5.6-and 7.2-fold as compared to the SP-based medium, which was related to the prolongation of B. subtilis natto lifespan with the increase in the optical density and cell length, and decrease in the dead rate to 13.5% in stationary phase, while the dead rate was 39.5% in the SP-based medium. Moreover, there was a significant correlation between key genes related to MK-7 and lifespan-related genes. The expression levels of growth-related autolysis genes skfF and sdp, which decreased cannibalism were downregulated 4.89-and 5.19-fold, respectively.The expression levels of cell division genes ftsZ and ftsL, which facilitated cell division process, were upregulated by 7.52-, 6.31-fold, respectively.Improved fermentation performances of B. subtilis natto were attributed to 2.26-fold increase in oligopeptides (Mw < 1 kDa) and moderate amino acids (these components come from the hydrolysis of soy protein by protamex1.6), particularly Phe, Arg and Glu in the medium of SPH+SP80. Meanwhile, the prolongation of the lifespan induced the MK-7 biosynthesis by upregulating the key genes on the cell membrane, such as menA and menD, which were upregulated by 1.43-and 1.47-fold, and therefore enhancing MK-7 precursor, and MK-7 assembly efficiency in B. subtilis natto. All these results revealed that prolongation of B. subtilis natto lifespan by SPH+SP80 was a potential and superior strategy for MK-7 production.
Keywords: menaquinone-7, Lifespan, Soy protein hydrolysate, Span 80, Bacillus subtilis natto
Received: 18 Feb 2025; Accepted: 05 May 2025.
Copyright: © 2025 Liu, Hu, Gao, Tao, Chen, Wu, Zhang, Han, Li and Zhou. 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: Yan Liu, Anhui Polytechnic University, Wuhu, China
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.