Université Paris-Saclay, INRAe, AgroPariTech, Micalis Institute, Jouy-en-Josas, France.
Department of Biological Sciences and Pathobiology, Institute of Microbiology, University of Veterinary Medicine, Vienna, Austria.
Appl Environ Microbiol. 2024 Sep 18;90(9):e0102924. doi: 10.1128/aem.01029-24. Epub 2024 Aug 19.
The group includes closely related spore-forming Gram-positive bacteria. In this group, plasmids play a crucial role in species differentiation and are essential for pathogenesis and adaptation to ecological niches. The emetic strains are characterized by the presence of the pCER270 megaplasmid, which encodes the non-ribosomal peptide synthetase for the production of cereulide, the emetic toxin. This plasmid carries several genes that may be involved in the sporulation process. Furthermore, a transcriptomic analysis has revealed that pCER270 influences the expression of chromosome genes, particularly under sporulation conditions. In this study, we investigated the role of pCER270 on spore properties in different species of the group. We showed that pCER270 plays a role in spore wet heat resistance and germination, with varying degrees of impact depending on the genetic background. In addition, pCER270 ensures that sporulation occurs at the appropriate time by delaying the expression of sporulation genes. This regulation of sporulation timing is controlled by the pCER270-borne Rap-Phr system, which likely regulates the phosphorylation state of Spo0A. Acquisition of the pCER270 plasmid by new strains could give them an advantage in adapting to new environments and lead to the emergence of new pathogenic strains.
The acquisition of new mobile genetic elements, such as plasmids, is essential for the pathogenesis and adaptation of bacteria belonging to the group. This can confer new phenotypic traits and beneficial functions that enable bacteria to adapt to changing environments and colonize new ecological niches. Emetic strains cause food poisoning linked to the production of cereulide, the emetic toxin whose synthesis is due to the presence of plasmid pCER270. In the environment, cereulide provides a competitive advantage in producing bacteria against various competitors or predators. This study demonstrates that pCER270 also regulates the sporulation process, resulting in spores with improved heat resistance and germination capacity. The transfer of plasmid pCER270 among different strains of the group may enhance their adaptation to new environments. This raises the question of the emergence of new pathogenic strains, which could pose a serious threat to human health.
该组包括密切相关的产孢子革兰氏阳性细菌。在该组中，质粒在物种分化中起着至关重要的作用，是致病和适应生态位所必需的。致吐菌株的特征是存在 pCER270 巨型质粒，该质粒编码非核糖体肽合成酶，用于产生呕吐毒素 cereulide。该质粒携带几个可能参与孢子形成过程的基因。此外，转录组分析表明，pCER270 影响染色体基因的表达，特别是在孢子形成条件下。在这项研究中，我们研究了 pCER270 在不同 组物种的孢子特性中的作用。我们表明，pCER270 在孢子耐热性和萌发中起作用，但其影响程度因遗传背景而异。此外，pCER270 通过延迟孢子形成基因的表达来确保在适当的时间进行孢子形成。这种孢子形成时间的调节受 pCER270 携带的 Rap-Phr 系统控制，该系统可能调节 Spo0A 的磷酸化状态。新菌株获得 pCER270 质粒可能使它们在适应新环境方面具有优势，并导致新的致病菌株的出现。
获得新的移动遗传元件，如质粒，对于属于 组的细菌的发病机制和适应至关重要。这可以赋予细菌新的表型特征和有益功能，使它们能够适应不断变化的环境并殖民新的生态位。致吐 菌株引起与呕吐毒素 cereulide 产生有关的食物中毒，该毒素的合成归因于质粒 pCER270 的存在。在环境中，cereulide 为产生细菌提供了与各种竞争者或捕食者竞争的优势。本研究表明，pCER270 还调节孢子形成过程，导致耐热性和萌发能力提高的孢子。质粒 pCER270 在 组不同菌株之间的转移可能增强它们对新环境的适应能力。这引发了新的致病菌株出现的问题，这可能对人类健康构成严重威胁。
