Tuning and Assessing Bacterial Predation Efficiency in Complex Environments

掠食性细菌捕食一系列其他细菌物种，并准备作为重要的生物防治剂。例如，该奖项将研究的细菌捕食者，Bdellovibrio bacteriovorus (Bb)，已知可以降解微生物生物膜，包括抗生素抗性膜，在废水处理中发挥作用，并显示出抑制动物和植物感染的潜力，赢得了“活抗生素”的称号。了解Bb的捕食策略和生命周期是开发Bb作为生物防治剂的先决条件。更重要的是，与小分子抗生素相比，利用细菌作为抗生素的能力具有明显的优势，因为细菌捕食者为我们提供了更多可调节的旋钮，可以帮助我们随意激活、调节或关闭它们的捕猎。在最近的工作中，研究人员探索了Bb在流体环境中如何利用周围的流体运动，被动地将自己推向猎物（如大肠杆菌）丰富的表面。这种寻找猎物的运动需要捕食者消耗能量，并提出了以下四个问题：1)Bb如何利用周围环境的线索来决定是否值得花费有限的资源去游泳以找到猎物？2)在饥饿条件和其他极端环境下，Bb如何根据与猎物的偶遇进行复制，调整速度以有效地定位猎物？换句话说，它们是以恒定的速度游泳，还是在快速和慢速之间交替游泳，以探索环境，同时尽可能地保存能量资源？3)将Bb限制在狭窄的环境中（例如Bb在它们所处环境的裂缝或裂缝中狩猎）如何放大捕食者水平的波动？换句话说，如果我们最终在下游使用Bb作为生物防治剂，我们能否在环境中保持Bb的稳定种群，或者它们的种群是否总是会发生重大变化？4)我们如何确定这些细菌捕食者在我们看不见它们的环境中（比如在活体动物体内）捕食的速度？换句话说，当我们不能用显微镜观察Bb捕食猎物时，我们如何监控它们的捕食效率，因为Bb可能在显微镜无法进入的区域内的样本中捕猎太深？总之，这些问题的答案构成了本奖项目标的基础。因此，这项工作的长期国家利益是能够调整细菌捕食者，使其成为有弹性和适应性的废水处理工具，对抗有害细菌，无论是天然的还是由恐怖主义威胁引入的，以及降解微生物生物膜。该奖项还将为STEM教育做出贡献。在亚利桑那州，绝大多数少数族裔学生通过进入少数族裔占70%的社区和其他公立大学开始他们的学术道路。虽然少数族裔学生对STEM领域的兴趣略高于白人学生，但这种兴趣并不能转化为STEM专业的大学毕业。为了帮助亚利桑那州立大学即将到来的社区大学人口适应STEM，我们提出了一个为期两周的夏季数据分析计划（SDAP）。SDAP将涵盖数据和不确定性处理方面的广泛主题，并直接受到该项目数据驱动工作的启发。参加SDAP的学生将从旨在将社区大学新生和其他少数民族学生融入大学社区的项目（如亚利桑那州立大学的SUNDIAL项目和IDEAs项目）中招募。学生将在为期两周的训练营中获得全额津贴，以帮助减少因参加SDAP而减少暑期工作的经济障碍。SDAP的每一天将由两部分组成：上午将包括2-3小时的教程，然后是分配的计算项目（在PI提供的笔记本电脑上）。亚利桑那州立大学的学院研究和评估服务团队（CREST）将帮助评估该项目的短期和长期影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Predatory bacteria prey on a range of other bacterial species and are poised to serve as important biocontrol agents. For example, the bacterial predator to be investigated with this award, Bdellovibrio bacteriovorus (Bb), is known to degrade microbial biofilms, including antibiotic resistant ones, plays a role in wastewater treatment, and shows potential to curb infections in animals and plants, earning it the title of “living antibiotic”. Understanding both Bb’s hunting strategy and life cycle are prerequisites toward exploiting Bb as a biocontrol agent. What is more, the ability to leverage bacteria as antibiotics has clear advantages as compared to small molecule antibiotics as bacterial predators provide us with many more tunable knobs to help potentially activate, modulate, or turn off their hunting at will.In recent work, the investigators explored how Bb use fluid motion around themselves as they propel through their fluid environments to passively push themselves towards surfaces where their prey, such as the bacterial species E. coli, are in abundance. This motion in search for its prey requires the predator to expend energy and begs the following four questions: 1) How do Bb use cues from their surroundings to determine whether it is worth expending their limited resources to swim in order to locate prey? 2) Under starvation conditions and other extreme environments, how do Bb, depending on chance encounters with their prey to replicate, adapt their speed to efficiently locate their prey? In other words, do they swim at constant speed or alternate between rapid and slow motion to explore their environment while preserving their energy resources as much as possible? 3) How does confining Bb in tight environments (as would be the case if Bb were hunting in a crevasse or a crack characteristic of the environments they live in) amplify the fluctuations in the levels of predator? In other words, can we maintain a steady population of Bb in an environment if we eventually use Bb as a biocontrol agent downstream or will their populations always undergo major variations? 4) How can we determine the rate at which these bacterial predators hunt in environments (such as within living animals) where we cannot see them? In other words, how can we monitor their predation efficiency when we cannot use microscopes to observe Bb hunting for prey as Bb may be hunting too deep within a sample in regions inaccessible to microscopes? Put together, answers to these questions form the basis of this award's goals. The longer term national interest of this work is therefore the ability to tune bacterial predators poised to become resilient, and adaptable, tools in wastewater treatment, the fight against harmful bacteria, both natural and introduced by terrorist threat, as well as to degrade microbial biofilms. This award will also contribute to STEM education. In Arizona, minority students overwhelmingly begin their academic path by attending community and other public colleges which are ∼70% minority. While minority students are slightly more interested in STEM fields than their white peers, this interest doesn’t translate into college graduation in STEM. To help ASU’s large incoming community college demographic acclimate to STEM, we propose a two-week Summer Data Analysis Program (SDAP). SDAP will cover a broad range of topics on the treatment of data and uncertainty and is directly inspired by the data-driven efforts of this project. Student attendees of SDAP will be recruited from programs already aimed at integrating community college recruits and other minority students into the university community (such as ASU’s SUNDIAL Program and IDEAs program). Students will be offered a full stipend over the 2 week bootcamp to help reduce economic disincentives associated with cutting back on summer work to attend SDAP. Each day in SDAP will consist of two parts: mornings will include a 2-3 hr tutorial followed by assigned computational projects (on laptops provided by the PI). ASU’s College Research and Evaluation Services Team (CREST) will help evaluate both short and long term impact of the project.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.