Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, QLD, 4072, Australia.
Department of Chemical and Bioprocess Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile.
J Ind Microbiol Biotechnol. 2020 Dec;47(12):1059-1073. doi: 10.1007/s10295-020-02330-3. Epub 2020 Nov 11.
Tetanus is a fatal disease caused by Clostridium tetani infections. To prevent infections, a toxoid vaccine, developed almost a century ago, is routinely used in humans and animals. The vaccine is listed in the World Health Organisation list of Essential Medicines and can be produced and administered very cheaply in the developing world for less than one US Dollar per dose. Recent developments in both analytical tools and frameworks for systems biology provide industry with an opportunity to gain a deeper understanding of the parameters that determine C. tetani virulence and physiological behaviour in bioreactors. Here, we compared a traditional fermentation process with a fermentation medium supplemented with five heavily consumed amino acids. The experiment demonstrated that amino acid catabolism plays a key role in the virulence of C. tetani. The addition of the five amino acids favoured growth, decreased toxin production and changed C. tetani morphology. Using time-course transcriptomics, we created a "fermentation map", which shows that the tetanus toxin transcriptional regulator BotR, P21 and the tetanus toxin gene was downregulated. Moreover, this in-depth analysis revealed potential genes that might be involved in C. tetani virulence regulation. We observed differential expression of genes related to cell separation, surface/cell adhesion, pyrimidine biosynthesis and salvage, flagellar motility, and prophage genes. Overall, the fermentation map shows that, mediated by free amino acid concentrations, virulence in C. tetani is regulated at the transcriptional level and affects a plethora of metabolic functions.
破伤风是由梭状芽孢杆菌属的破伤风梭菌感染引起的致命疾病。为了预防感染，近一个世纪前开发的类毒素疫苗被常规用于人类和动物。该疫苗被列入世界卫生组织基本药物清单，在发展中国家可以非常廉价地生产和管理，每剂不到 1 美元。近年来，系统生物学的分析工具和框架的发展为行业提供了一个机会，可以更深入地了解决定破伤风梭菌在生物反应器中的毒力和生理行为的参数。在这里，我们比较了传统发酵工艺和补充了五种大量消耗氨基酸的发酵培养基。实验表明，氨基酸分解代谢在破伤风梭菌的毒力中起着关键作用。这五种氨基酸的添加有利于生长，减少毒素的产生，并改变破伤风梭菌的形态。通过时间过程转录组学，我们创建了一个“发酵图谱”，表明破伤风毒素转录调节因子 BotR、P21 和破伤风毒素基因的表达下调。此外，这种深入分析揭示了可能参与破伤风梭菌毒力调节的潜在基因。我们观察到与细胞分离、表面/细胞粘附、嘧啶生物合成和回收、鞭毛运动以及噬菌体基因相关的基因的差异表达。总的来说，发酵图谱表明，通过游离氨基酸浓度的介导，破伤风梭菌的毒力在转录水平上受到调节，并影响多种代谢功能。
