Stoodley Paul, Toelke Nina, Schwermer Carsten, de Beer Dirk
National Centre for Advanced Tribology at Southampton, (NCATS), Mechanical Engineering, University of Southampton, Southampton, SO17 1BJ, UK.
Department of Microbial Infection and Immunity, Department of Orthopaedics, The Ohio State University, 716 Biomedical Research Tower (BRT), 460 W 12th Ave, Columbus OH, 43210, United States.
Biofilm. 2024 Feb 10;7:100181. doi: 10.1016/j.bioflm.2024.100181. eCollection 2024 Jun.
is a biofilm forming pathogen commonly associated with infection of the cystic fibrosis (CF) lung, chronic wounds and indwelling medical devices. is a facultative aerobe that can use nitrate (NO) found in healthy and infected tissues and body fluids to generate energy through denitrification. Further, the expression of denitrification genes has been found in specimens from people with CF. The main aim of this study was to determine the relative energy contribution of oxygen (O) respiration and denitrification in single PAO1 biofilm colonies under different O concentrations to estimate the possible relative importance of these metabolic processes in the context of biofilm infections. We showed that the used strain PAO1 in biofilms denitrified with nitrous oxide (NO), and not nitrogen (N), as the end product in our incubations. From simultaneous O and NO microprofiles measured with high spatial resolution by microsensors in agar colony biofilms under air, N and pure O, the rates of aerobic respiration and denitrification were calculated and converted to ATP production rates. Denitrification occurred both in the oxic and anoxic zones, and became increasingly dominant with decreasing O concentrations. At O concentrations characteristic for tissues and wounds (20-60 μM), denitrification was responsible for 50% of the total energy conservation in the biofilm. In addition the formation of nitric oxide (NO), a precursor of NO and an important regulator of many cellular processes, was strongly influenced by the local O concentrations. NO production was inhibited under pure O, present under anoxia (∼1 μM) and remarkably high (up to 6 μM) under intermediate O levels, which can be found in infected tissues. Possible impacts of such NO levels on both the host and the biofilm bacteria are discussed.
是一种形成生物膜的病原体，通常与囊性纤维化（CF）肺部感染、慢性伤口和植入式医疗设备感染有关。它是一种兼性需氧菌，可利用健康和感染组织及体液中的硝酸盐（NO）通过反硝化作用产生能量。此外，在CF患者的标本中发现了反硝化基因的表达。本研究的主要目的是确定在不同氧气（O）浓度下，单个PAO1生物膜菌落中氧气呼吸和反硝化作用的相对能量贡献，以估计这些代谢过程在生物膜感染背景下可能的相对重要性。我们发现，在我们的培养中，生物膜中使用的PAO1菌株以一氧化二氮（N₂O）而非氮气（N）作为反硝化的终产物。通过微传感器在空气、氮气和纯氧条件下对琼脂菌落生物膜进行高空间分辨率的同步氧气和一氧化氮微剖面测量，计算了有氧呼吸和反硝化作用的速率，并将其转换为ATP产生速率。反硝化作用在有氧区和缺氧区均有发生，且随着氧气浓度的降低，其作用越来越占主导地位。在组织和伤口特有的氧气浓度（20 - 60 μM）下，反硝化作用占生物膜中总能量保存的50%。此外，一氧化氮（NO）的前体NO的形成以及许多细胞过程的重要调节因子，受到局部氧气浓度的强烈影响。在纯氧条件下，NO的产生受到抑制，在缺氧（约1 μM）时存在，而在感染组织中可发现的中等氧气水平下则显著升高（高达6 μM）。讨论了这种NO水平对宿主和生物膜细菌的可能影响。
