Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.
J Bacteriol. 2022 Jan 18;204(1):e0039621. doi: 10.1128/JB.00396-21. Epub 2021 Oct 25.
Pseudomonas aeruginosa forms surface-attached communities that persist in the face of antimicrobial agents and environmental perturbation. Published work has found that extracellular polysaccharide (EPS) production, regulation of motility, and induction of stress response pathways contribute to biofilm tolerance during such insults. However, little is known regarding the mechanism(s) whereby biofilm maintenance is regulated when exposed to such environmental challenges. Here, we provide evidence that the diguanylate cyclase YfiN is important for the regulation of biofilm maintenance when exposed to peroxide. We find that compared to the wild type (WT), static biofilms of the Δ mutant exhibit a maintenance defect, which can be further exacerbated by exposure to peroxide (HO); this defect can be rescued through genetic complementation. Additionally, we found that the Δ mutant biofilms produce less c-di-GMP than WT and that HO treatment enhanced motility of surface-associated bacteria and increased cell death for the Δ mutant grown as a biofilm compared to WT biofilms. These data provide evidence that YfiN is required for biofilm maintenance by P. aeruginosa, via c-di-GMP signaling, to limit motility and protect viability in response to peroxide stress. These findings add to the growing recognition that biofilm maintenance by P. aeruginosa is an actively regulated process that is controlled, at least in part, by the wide array of c-di-GMP metabolizing enzymes found in this microbe. We build on previous findings that suggest that Pseudomonas aeruginosa utilizes c-di-GMP metabolizing enzymes to actively maintain a mature biofilm. Here, we explore how the diguanylate cyclase YfiN contributes to the regulation of biofilm maintenance during peroxide exposure. We find that mature P. aeruginosa biofilms require YfiN to synthesize c-di-GMP, regulate motility, and ensure viability during peroxide stress. These findings provide further evidence that the modulation of c-di-GMP in response to environmental signals is an important mechanism by which biofilms are maintained.
铜绿假单胞菌形成附着在表面的群落，在面对抗菌剂和环境干扰时能持续存在。已发表的研究发现，胞外多糖（EPS）的产生、运动性的调节以及应激反应途径的诱导有助于在受到这些损伤时对抗生物膜的耐受性。然而，对于在暴露于此类环境挑战时如何调节生物膜维持的机制，人们知之甚少。在这里，我们提供了证据表明，双鸟苷酸环化酶 YfiN 在暴露于过氧化物时对生物膜维持的调节很重要。我们发现，与野生型（WT）相比，Δ突变体的静态生物膜表现出维持缺陷，而过氧化物（HO）的暴露会进一步加剧这种缺陷；通过遗传互补可以挽救这种缺陷。此外，我们发现Δ突变体生物膜产生的 c-di-GMP 比 WT 少，并且 HO 处理增强了表面相关细菌的运动性，并增加了与 WT 生物膜相比作为生物膜生长的Δ突变体的细胞死亡。这些数据提供了证据表明，YfiN 通过 c-di-GMP 信号通路，需要为铜绿假单胞菌的生物膜维持提供，以限制运动性并保护在过氧化物应激下的生存能力。这些发现增加了越来越多的认识，即铜绿假单胞菌的生物膜维持是一个主动调节的过程，至少部分受到该微生物中广泛存在的 c-di-GMP 代谢酶的控制。我们基于先前的研究结果，即铜绿假单胞菌利用 c-di-GMP 代谢酶来积极维持成熟的生物膜。在这里，我们探索了双鸟苷酸环化酶 YfiN 如何在暴露于过氧化物时有助于调节生物膜维持。我们发现，成熟的铜绿假单胞菌生物膜需要 YfiN 来合成 c-di-GMP、调节运动性并确保在过氧化物应激下的生存能力。这些发现提供了进一步的证据，表明 c-di-GMP 对环境信号的调节是维持生物膜的重要机制。
