Hashem Ihab, Van Impe Jan F M
BioTeC+ & OPTEC, Department of Chemical Engineering, KU Leuven, Ghent, Belgium.
Front Microbiol. 2022 Feb 25;13:812763. doi: 10.3389/fmicb.2022.812763. eCollection 2022.
Quorum sensing is a cell-cell communication system that bacteria use to express social phenotypes, such as the production of extracellular enzymes or toxins, at high cell densities when these phenotypes are most beneficial. However, many bacterial strains are known to lack a sensing mechanism for quorum signals, despite having the gene responsible for releasing the signals to the environment. The aim of this article is 2-fold. First, we utilize mathematical modeling and signaling theory to elucidate the advantage that a bacterial species can gain by releasing quorum signals, while not being able to sense them, in the context of ecological competition with a focal quorum sensing species, by reducing the focal species' ability to optimize the timing of expression of the quorum sensing regulated phenotype. Additionally, the consequences of such "dishonest signaling," signaling that has evolved to harm the signal's receiver, on the focal quorum sensing species are investigated. It is found that quorum sensing bacteria would have to incur an additional, strategic, signaling cost in order to not suffer a reduction in fitness against dishonest signaling strains. Also, the concept of the Least Expensive Reliable Signal is introduced and applied to study how the properties of the regulated phenotype affect the metabolic investment in signaling needed by the quorum sensing bacteria to withstand dishonest signaling.
群体感应是一种细胞间通讯系统，细菌利用它在细胞密度高时表达社会表型，比如产生胞外酶或毒素，此时这些表型最为有益。然而，已知许多细菌菌株尽管拥有负责向环境释放信号的基因，但却缺乏对群体感应信号的感应机制。本文的目的有两个。首先，我们运用数学建模和信号理论来阐明，在与一个关键的群体感应物种进行生态竞争的背景下，一个细菌物种通过释放群体感应信号但无法感应它们，能够获得何种优势，即降低关键物种优化群体感应调控表型表达时间的能力。此外，还研究了这种“不诚实信号传递”（即进化为损害信号接收者的信号传递）对关键群体感应物种的影响。研究发现，群体感应细菌为了不遭受针对不诚实信号传递菌株的适应性降低，将不得不承担额外的、策略性的信号传递成本。同时，引入了“最便宜可靠信号”的概念，并应用于研究调控表型的特性如何影响群体感应细菌为抵御不诚实信号传递而进行信号传递所需的代谢投入。
