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，并有望成为重要的生防剂。例如，该奖项将研究的细菌捕食者--细小芽孢杆菌(Bb)，众所周知会降解微生物生物膜，包括具有抗生素耐药性的微生物生物膜，在废水处理中发挥作用，并显示出抑制动植物感染的潜力，使其获得“活抗生素”的称号。了解BB的捕食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可调的旋钮，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是如何利用自己周围的流体运动，推动它们穿过流体环境，被动地将自己推向猎物的表面，比如细菌种类大肠杆菌。这种寻找猎物的运动需要捕食者消耗能量，并回避了以下四个问题：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来定位猎物？2)在饥饿条件和其他极端环境下，BB如何根据与猎物的偶然相遇进行复制，调整它们的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，还是在快慢运动之间交替游动，以探索环境，同时尽可能地保留它们的能源？3)将BB限制在狭窄的环境中(如果BB在裂缝或裂缝中狩猎，这是它们生活环境的特征)如何放大捕食者水平的波动？换句话说，如果我们最终将BB用作下游的生防剂，我们能否在一个环境中保持BB的稳定种群，或者它们的种群总是会经历重大变化？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(如在活的动物体内)捕食的速度？换句话说，当我们不能使用显微镜观察BB捕猎猎物时，我们如何监测它们的捕食效率，因为BB可能在显微镜无法接触到的区域的样本中狩猎太深？总而言之，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的能力，使其成为具有弹性和适应性的废水处理工具，打击天然和由恐怖主义威胁引入的有害细菌，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参加社区和其他公立大学开始他们的学业之路，这些大学中有70%是∼少数族裔。虽然少数族裔学生比他们的白人同龄人对STEM领域略有兴趣，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量新生社区大学适应STEM，我们提出了一个为期两周的夏季数据分析计划(SDAP)。SDAP将涵盖处理数据和不确定性的广泛主题，并直接受到该项目以数据为导向的努力的启发。SDAP的学生参与者将从旨在将社区大学招生和其他少数族裔学生融入大学社区的计划中招募(如亚利桑那州立大学的日规计划和IDEAS计划)。学生将在为期两周的训练营中获得全额津贴，以帮助减少与削减暑期工作参加SDAP相关的经济障碍。SDAP的每一天将由两部分组成：早上将包括2-3小时的教程，然后是指定的计算项目(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NSF的法定使命，并通过使用基金会的智力优势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.