Collaborative Research: Ammonia oxidizers and their heterotrophic friends

微生物在全球氮循环中起着重要作用。一组细菌，氨氧化细菌，将氨氧化为亚硝酸盐，因此在去除废水处理厂人源尿素中的氨方面发挥关键作用。在自然界中，多种微生物以复杂的方式共存和相互作用。不同的微生物群落可以比单一物种更有效地发挥重要功能。氨氧化细菌就是一个例子，在微生物群落中，氨的转化比氧化细菌单独存在时更有效。然而，改善氨转化的微生物邻居之间的相互作用尚未得到很好的理解。该项目的目标是更好地了解生活在微生物群落中如何提高氨氧化细菌转化氨的能力。该项目的另一个目标是教育不同群体的学生了解微生物群落的重要性，并提高对水质的认识和紧迫性。研究生和本科生将接受最先进的微生物学技术培训，并参与研究。来自俄亥俄州农村的小学生和非微生物学专业的本科生将被教授微生物群落、硝化作用和水质的重要性。这项研究将为细菌群落内的协同相互作用提供重要的见解，并增加操纵微生物群落以改善或期望功能的能力，例如废水厂中的微生物群落以改善氨的去除。氨氧化细菌（AOB）将氨氧化为亚硝酸盐。AOB是硝化作用的核心贡献者，硝化作用是全球氮循环的关键步骤。作为微生物群落的一部分，AOB与亚硝酸盐氧化菌和异养菌正相互作用。已经有研究表明，亚硝酸盐氧化细菌将AOB周围的有毒亚硝酸盐水平保持在较低水平，从而维持有利于AOB生长的有利环境。AOB与异养细菌正相互作用的机制尚未阐明。这些积极的相互作用将在定义良好的实验室共培养、富集培养和原生环境中进行研究。实验将包括：(1)在异养细菌存在下对AOB亚硝化单胞菌sp. Is79进行蛋白质组学和转录组学分析；(2)在异养菌存在下，对另外3株AOB菌株进行蛋白质组学分析；(3)在原始环境中培养的AOB蛋白质组学分析。研究人员将对结果进行分析，以确定菌株特异性生理反应，从而确定AOB与异养细菌之间相互作用的性质。了解受异养细菌影响的AOB的分子机制和代谢途径将为自养-异养相互作用的研究领域提供新的思路。本研究还将探讨在实验室纯培养物、实验室富集培养物和原始环境中生长的AOB的生理异同。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。

Microorganisms play a major role in the global nitrogen cycle. One group of bacteria, ammonia oxidizing bacteria, oxidize ammonium to nitrite and thus play a key role in the removal of ammonium from human derived urea in wastewater treatment plants. In nature, diverse microorganisms coexist and interact in complex ways. Communities of different microorganisms can perform vital functions more efficiently than single species achieve alone. Ammonia oxidizing bacteria are one example, where ammonia is converted more efficiently when in a microbial community than when the oxidizing bacteria are alone. Yet, the interactions among microbial neighbors that improve ammonia conversion are not well understood. The goal of this project is to better understand how living in microbial communities improves ammonia oxidizing bacteria's ability to convert ammonia. An additional goal of this project is to educate a diverse group of students on the importance of microbial communities, and to raise awareness and urgency about water quality. Graduate and undergraduate students will be trained in state of the art microbiology techniques and involved in the research. Elementary school students from rural Ohio and undergraduate non-microbiology majors will be taught about the importance of microbial communities, nitrification, and water quality. This research will provide important insight into synergistic interactions within bacterial communities and increase the ability to manipulate microbial communities for improved or desired function, such as those in wastewater plants to improve ammonia removal.Ammonia-oxidizing bacteria (AOB) oxidize ammonia to nitrite. AOB are core contributors to nitrification, a crucial step in the global nitrogen cycle. As part of microbial communities, AOB positively interact with nitrite-oxidizing bacteria and heterotrophic bacteria. It has already been shown that the nitrite-oxidizing bacteria keep the level of toxic nitrite around AOB low, maintaining a beneficial environment that allows for AOB growth. The mechanisms underlying the positive interactions of AOB with heterotrophic bacteria have not been elucidated. These positive interactions will be investigated in well-defined laboratory co-cultures, enrichment cultures, and native environments. Experiments will include (1) proteome and transcriptome analysis of the AOB Nitrosomonas sp. Is79 in the presence of heterotrophic bacteria as single and mixed cultures; (2) proteome analysis of three additional AOB strains in the presence of heterotrophic bacteria; and (3) proteome analysis of an AOB incubated in their original environment. The results will be analyzed to identify strain-specific physiological responses in order to determine the nature of the interactions between AOB and heterotrophic bacteria. Insights into the molecular mechanisms and metabolic pathways in AOB that are impacted by heterotrophic bacteria will add to the growing field of research on autotrophic-heterotrophic interactions. This research will also address the physiological similarities and differences in AOB grown in laboratory pure cultures, in laboratory enrichment cultures, and in their original environments.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.