ISS: The Influence of Microgravity on Bacterial Transport and Pellicle Morphogenesis

ISS：微重力对细菌运输和菌膜形态发生的影响

• 批准号: 2323019
• 负责人: Howard Stone
• 金额: $ 34万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2323019&HistoricalAwards=false
• 关键词: ISS; Influence; Microgravity; Bacterial; Transport

This award investigates the formation and growth of pellicles, which are membrane-like bacterial communities that accumulate at liquid interfaces. Pellicles are found in many settings and contribute to food spoilage, hospital infections, and environmental contamination. Pellicles formed at air/water interfaces exhibit distinct properties and formation dynamics compared to biofilms formed on solid interfaces, e.g., they undergo complex changes in shape over time and are strongly influenced by oxygen availability. Experiments in microgravity provide a unique opportunity to investigate two unexplored aspects of pellicle growth: (1) the role of gravity-driven mechanisms for bacteria and oxygen transport near an interface, and (2) growth at a spherical interface. Studying pellicle growth patterns at spherical interfaces can yield insights into how soft living materials behave, which is valuable for tissue engineering and biomaterials. By understanding the transport mechanisms underlying pellicle growth, pellicles can be controlled for purposes such as food preservation, infection control, and environmental remediation.Experiments will be conducted using the Ring Shear Drop module aboard the International Space Station, which enables deployment of centimeter-scale drops constrained by surface tension. Drops in microgravity can be used as container-less reactors for studying phenomena at air/liquid interfaces. Two facets of pellicle formation will be investigated: (1) initial transport of bacteria and oxygen to the interface in the absence of gravity-driven convection and sedimentation over short timescales (2-6 hours), and (2) morphogenesis of pellicles at a spherical drop interface over long timescales (48 hours). Numerical modeling will supplement experiments to decipher the individual contributions of specific transport processes responsible for pellicle morphogenesis. By comparing results from microgravity experiments to Earth-based controls, the effects of gravity on pellicle formation can be distinguished. Microgravity is known to significantly affect bacterial biofilms at solid surfaces, and it is expected that microgravity will exert an even greater influence on pellicle growth at elastic fluid interfaces. Exploring this influence will enable valuable insights into mechanisms responsible for initial adhesion, growth, and proliferation of pellicles. This award will also characterize pellicle morphogenesis at the drop air/water interface, focusing on the out-of-plane buckling transitions that occur due to interfacial instabilities and compressive stresses generated by growth. Pellicle dynamics on three-dimensional curved shapes with approximately spherical boundaries can serve as a model system that mimics natural transitions observed in soft living materials. Because microgravity enables deployment of centimeter scale droplets, this award will be the first to observe pellicle morphogenesis at spherical interfaces.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项调查了颗粒的形成和生长，这些细胞是膜状细菌群落积聚在液体界面上的。在许多情况下都发现了颗粒，并导致食物变质，医院感染和环境污染。与在固体界面上形成的生物膜相比，在空气/水接口处形成的颗粒具有不同的特性和地层动力学，例如，它们会随着时间的推移而发生复杂的形状变化，并且受氧气可用性的强烈影响。微重力实验提供了一个独特的机会，可以研究颗粒生长的两个未开发的方面：（1）界面附近的细菌和氧运输的重力驱动机制的作用，以及（2）在球形界面上的生长。在球形界面上研究颗粒的生长模式可以使人们能够洞悉柔软的生活材料的行为方式，这对于组织工程和生物材料很有价值。通过了解颗粒生长的基础运输机制，可以为诸如食品保存，感染控制和环境修复之类的目的控制颗粒。将使用国际空间站上的环形剪切模块进行实例，这可以部署通过表面张力来限制厘米尺度的下降。微重力的滴剂可以用作无容器的反应堆，用于研究空气/液体界面的现象。将研究两个颗粒形成的方面：（1）在短时间（2-6小时）中没有重力驱动的对流和沉降的情况下，细菌和氧气的初始运输（2-6小时），以及（2）长时间（48小时）在球形滴界面上的圆柱形成（48小时）。数值建模将补充实验，以破译负责颗粒形态发生的特定运输过程的个体贡献。通过将微重力实验的结果与基于地球的对照进行比较，可以区分重力对颗粒形成的影响。已知微重力会显着影响固体表面的细菌生物膜，并且预计微重力对弹性流体界面处的细胞生长的影响更大。探索这种影响将使对负责初始粘附，生长和颗粒增殖的机制有价值的见解。该奖项还将表征在滴空气/水界面处的细胞形态发生，重点是由于界面不稳定性和生长产生的压缩应力而发生的平面外屈曲过渡。具有近似球形边界的三维弯曲形状上的颗粒动力学可以用作模型系统，该模型模仿在软生物中观察到的自然过渡。由于微重力能够部署厘米液滴，因此该奖项将是第一个在球形接口处观察细胞形态发生的奖项。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的审查标准通过评估来通过评估来获得支持的。