PDF(Pubmed)
Abstract：
Biofilm is a group of heterogeneously structured and densely packed bacteria with limited access to nutrients and oxygen. These intrinsic features can allow a mono-species biofilm to diversify into polymorphic subpopulations, determining the overall community\'s adaptive capability to changing ecological niches. However, the specific biological functions underlying biofilm diversification and fitness adaptation are poorly demonstrated. Here, we launched and monitored the experimental evolution of Pseudomonas aeruginosa biofilms, finding that two divergent molecular trajectories were adopted for adaptation to higher competitive fitness in biofilm formation: one involved hijacking bacteriophage superinfection to aggressively inhibit kin competitors, whereas the other induced a subtle change in cyclic dimeric guanosine monophosphate signaling to gain a positional advantage via enhanced early biofilm adhesion. Bioinformatics analyses implicated that similar evolutionary strategies were prevalent among clinical P. aeruginosa strains, indicative of parallelism between natural and experimental evolution. Divergence in the molecular bases illustrated the adaptive values of genomic plasticity for gaining competitive fitness in biofilm formation. Finally, we demonstrated that these fitness-adaptive mutations reduced bacterial virulence. Our findings revealed how the mutations intrinsically generated from the biofilm environment influence the evolution of P. aeruginosa.
摘要：
生物膜是一组异质结构和密集包装的细菌，对营养和氧气的获取有限。这些内在特征可以允许单物种生物膜多样化为多态亚群，确定整个群落对生态位变化的适应能力。然而,生物膜多样化和适应性适应的特定生物学功能表现不佳。这里,我们启动并监测了铜绿假单胞菌生物膜的实验进化，发现采用两种不同的分子轨迹来适应生物膜形成中更高的竞争适应性：一种涉及劫持噬菌体超感染以积极抑制亲属竞争者，而另一种诱导c-di-GMP信号的细微变化，通过增强早期生物膜粘附获得位置优势。生物信息学分析暗示，类似的进化策略在临床铜绿假单胞菌菌株中普遍存在，表明自然进化和实验进化之间的平行性。分子基础的分歧说明了基因组可塑性在生物膜形成中获得竞争性适应性的适应性价值。最后,我们证明,这些适应性突变降低了细菌毒力.我们的发现揭示了由生物膜环境固有产生的突变如何影响铜绿假单胞菌的进化。
