Collaborative Research: Creatine Cycling in Marine Bacterial and Phytoplankton Assemblages

在水生系统中，溶解有机氮(DON)的高比率产生和利用通常归因于微生物活动。虽然众所周知，生物可利用DON的生产和消费之间存在着紧密的耦合，但人们对这种快速循环的DON池的组成、动力学和生态意义了解较少。这项提议侧重于DON池的一种成分肌酸，它在历史上被认为是后生动物活动的产物，但似乎既由浮游植物产生，又由海洋细菌消耗。肌酸以可测量的量存在于海水中，这导致了肌酸可能是海洋DON循环的重要组成部分的假设。DON循环可能与基本的海洋生态系统过程有关，对全球范围内的碳和氮周转具有重大影响。该项目的更广泛影响将包括通过教师的研究经验将科学家与K-12学生联系起来，以及与俄克拉荷马大学全州教育研究和发展中心K20教育和社区更新中心合作开展课程。该项目将通过在海洋科学和微生物生态学方面的真实研究经验，将研究与农村中学科学教师的探究式教学相结合。K20网络包括俄克拉荷马州96%的学校，提供了一个独特的机会来影响俄克拉荷马州的STEM教育。该项目的结果将有助于更好地理解DON自行车运动，肌酸摄取活动的生态背景，并确定海洋环境中产生肌酸和消费肌酸的生物。肌酸循环的重要性将通过沿北大西洋观察到的从海岸到近海的自然生产力梯度的15N示踪剂研究来评估。将使用示踪剂和分子方法来研究浮游植物和细菌在肌酸吸收中的重要性，并将通过分子、稳定同位素探测(SIP)和RT-qPCR方法来询问利用细菌的肌酸的分类身份。

High rates of dissolved organic nitrogen (DON) production and utilization in aquatic systems are typically attributed to microbial activity. Though it is known that there is a tight coupling between the production and consumption of biologically available DON, the composition, dynamics, and ecological significance of this rapidly cycled DON pool are less well understood. This proposal focuses on a component of the DON pool, creatine, which is historically understood as a product of metazoan activity, but appears to be both produced by phytoplankton and consumed by marine bacteria. Creatine is present in seawater in measurable quantities, which led to the hypothesis that creatine may be significant component of the marine DON cycle. DON cycling likely has a bearing on fundamental marine ecosystem processes with large implications for carbon and nitrogen turnover on a global scale. Broader impacts of this project will include outreach that focuses on connecting scientists with K-12 students through research experiences for teachers and lesson development in collaboration with the K20 Center for Educational and Community Renewal, a statewide education research and development center at the University of Oklahoma. The project will integrate the research with inquiry-based teaching of rural secondary science teachers through Authentic Research Experiences in oceanographic science and microbial ecology. The K20 network includes 96% of Oklahoma schools, providing a unique opportunity to impact STEM education in Oklahoma.The results of this project will help develop a better understanding of DON cycling, the ecological context of creatine uptake activity, and identify both creatine producing and consuming organisms in the marine environment. The importance of creatine cycling will be assessed via 15N tracer studies along the natural coastal-to-offshore productivity gradient observed in the North Atlantic. Tracer and molecular approaches will be used to investigate the importance of phytoplankton vs. bacteria in creatine uptake and, the taxonomic identities of creatine utilizing bacteria will be interrogated via molecular, stable isotope probing (SIP), and RT-qPCR approaches.