RUI: Acid and Base Stress in Escherichia coli

知识专长：通过pH测量的酸和碱对于促进和/或控制细菌在从土壤和水到人体皮肤和肠道的所有环境中的生长和存活是重要的。微生物在食品生产过程中形成酸，酸是重要的食品防腐剂。酸和碱影响生物燃料和药物的微生物生产。酸和碱的产生改变了生长细菌的外部环境，但运输和代谢机制帮助细菌细胞在外部酸或碱胁迫下保持内部接近恒定的pH值。目前所了解的细菌对外部环境变化的适应性大多适用于在实验室条件下在液体培养基中生长的通气培养物。 这项研究将确定大肠杆菌如何在自然环境中发现的条件下（如低氧和生物膜）对酸胁迫和碱胁迫作出反应。本科研究人员将采用荧光显微镜和实验室进化来解决：（1）细菌细胞如何调节pH值，因为他们分裂和经历极性老化？(2)pH胁迫如何引起氧化胁迫（3）细菌如何在酸性胁迫下进化，以在比祖先菌株更低的pH下生长这些问题的答案将有助于发酵工业设计改进的食品防腐剂和生物技术工艺。更广泛的重要性：该项目将通过继续由本科生进行的生产性研究计划，为国家的人力资源做出贡献。每年，10名一年级的学生研究人员将从凯尼恩学院STEM项目和科学课程，以及2名高中生招募。学生将学习微生物学研究的基本技术，同时与生物学385研究和生物学497高级荣誉更先进的同行合作。他们将编写自己的小型提案，设计和进行实验，并起草手稿供出版。许多本科生被吸引到这个项目中工作，决定从事科学事业。学生们还将担任高中科学博览会的评委，并为经济条件差的社区成员提供材料和演示。

INTELLECTUAL MERIT: Acid and base, as measured by pH, are important to promote and/or control bacterial growth and survival in all environments, from soil and water to the human skin and intestine. Microbes form acids during food production, and acids are important food preservatives. Acid and base influence microbial production of biofuels and pharmaceuticals. Acid and base production change the external environment of growing bacteria but mechanisms of transport and metabolism help bacterial cells maintain near-constant pH inside, under acid or base stress from outside. Most of what is currently understood on bacterial adaptation to changes in the external environment applies to aerated cultures grown in liquid medium under laboratory conditions. This research will identify how the bacterium Escherichia coli responds to acid stress and base stress under conditions found in natural environments, such as low oxygen and biofilms. Undergraduate researchers will employ fluorescence microscopy and laboratory evolution to address: (1) How do bacterial cells regulate pH as they divide and undergo polar aging? (2) How does pH stress cause oxidation stress (3) How do bacteria evolve under acid stress to grow at lower pH than the ancestral strain The answers to these questions will help the fermentation industry devise improved food preservatives and processes for biotechnology.BROADER IMPACTS: The project will contribute to the nation's human resources by continuing a productive research program run by undergraduates. Each year, 10 first-year student researchers will be recruited from the Kenyon College STEM programs and science classes, as well as 2 high school students. Students will learn fundamental techniques of microbiological research while working with more advanced peers in BIOL 385 Research in Biology and BIOL 497 Senior Honors. They will write their own mini-proposals, design and conduct the experiments, and draft the manuscript for publication. Many undergraduates attracted to work on this project decide to pursue careers in science. Students will also serve as judges for the high-school science fair, and provide materials and demonstrations for members of an economically underserved community.