Tuning and Assessing Bacterial Predation Efficiency in Complex Environments

捕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控制剂。例如，该奖项将调查的细菌捕食者蛭弧菌（Bb）已知可降解微生物生物膜，包括抗生素抗性生物膜，在废水处理中发挥作用，并显示出遏制动植物感染的潜力，赢得了“活抗生素”的称号。了解Bb的狩猎策略和生活史是开发Bb作为生防剂的先决条件。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的可调旋钮，以帮助潜在地激活，调节或随意关闭它们的狩猎。在最近的工作中，研究人员探索了Bb如何在它们通过流体环境推进时利用自身周围的流体运动来被动地将自己推向它们的猎物，例如细菌种类E。大肠杆菌中，有大量的。这种寻找猎物的运动需要捕食者消耗能量，并引出以下四个问题：1）Bb如何利用周围环境的线索来确定是否值得花费有限的资源游泳以定位猎物？ 2)在饥饿条件和其他极端环境下，Bb如何依靠与猎物的偶然相遇来复制，以适应它们的速度来有效地定位猎物？ 换句话说，它们是以恒定的速度游泳，还是在快速和缓慢运动之间交替，以探索它们的环境，同时尽可能地保存它们的能量资源？ 3)把Bb限制在狭窄的环境中（就像Bb在裂缝或裂缝中狩猎一样）是如何放大捕食者水平的波动的？换句话说，如果我们最终使用Bb作为下游的生物控制剂，我们能否在环境中保持Bb的稳定种群，或者它们的种群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到它们的环境中（例如在活的动物体内）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，我们如何监测它们的捕食效率，因为Bb可能在显微镜无法到达的区域内的样品中捕食得太深了？这些问题的答案构成了该奖项目标的基础。因此，这项工作的长期国家利益是能够调整细菌捕食者，使其成为废水处理中具有弹性和适应性的工具，与自然和恐怖主义威胁引入的有害细菌作斗争，以及降解微生物生物膜。 该奖项也将有助于STEM教育。在亚利桑那州，绝大多数少数民族学生开始他们的学术道路，参加社区和其他公立大学，其中70%是少数民族。虽然少数民族学生对STEM领域的兴趣略高于他们的白色同龄人，但这种兴趣并不能转化为STEM的大学毕业。为了帮助亚利桑那州立大学的大型社区学院人口适应干，我们提出了为期两周的夏季数据分析计划（SDAP）。SDAP将涵盖有关数据和不确定性处理的广泛主题，并直接受到该项目数据驱动工作的启发。SDAP的学生参与者将从已经旨在将社区学院新兵和其他少数民族学生融入大学社区的计划（如ASU的SUNDIAL计划和IDEAS计划）中招募。学生将在为期2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抑制因素。SDAP的每一天将包括两个部分：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）将帮助评估项目的短期和长期影响。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.