Control of Stability of Shewanella oneidensis MR-1 Biofilms

自然界中的大多数微生物被认为存在于生物膜中，这些生物膜在几乎任何水界面的生物或非生物表面上发育。这些表面相关的结构化微生物群落具有医学和环境重要性。成熟生物膜的稳定性和弹性由两个相互关联的细胞过程控制：附着和脱离。然而，分离和附着的潜在分子机制在很大程度上是未知的。该项目探索了对分离/附着过程的生理，遗传和生物化学理解的第一步。希瓦氏菌（Shewanella oneidensis）MR-1是一种地球化学上重要的微生物，它与生物膜中的含铁和锰的土壤矿物进行代谢相互作用，作为这些研究的模式微生物。多层次的方法涉及分离的生理学研究，包括能量和细胞混合实验。本研究的预期结果应该为微生物从生物膜中脱离的分子机制提供基本的见解。 虽然在过去已经研究了生物膜形成的初始过程，但尚未解决控制已建立的生物膜的稳定性及其长期存活的重要问题。这些研究将揭示一些重要的生理，机械和遗传的原则，确定生物膜stability.Broader ImpactThis研究将产生对微生物生物膜的生物学基础知识和教育研究生和本科生和更广泛的社区。该实验室有吸引和留住少数民族的记录（实验室70%是女性，33%是少数民族）。PI每年教授三门环境微生物学课程，包括一个关于“环境与人类健康”的新的大二研讨会。“整个实验室活动的更广泛影响是在几个层面上。在过去的四年里，主要研究者担任马萨诸塞州伍兹霍尔MBL“微生物多样性课程”的共同主任; 2003/04年担任NRC/NAS“未来使用和生产氢的替代品和战略”委员会成员;主要研究者是制作“DNA档案”的声音视觉科学咨询委员会成员;自2000年起担任斯坦福大学生物膜研究中心主任，自2002年起担任加利福尼亚州阿西洛马市年度“西海岸细菌生理学家会议”的共同组织者;自2003年起担任斯坦福大学环境工程与科学项目的项目协调员。 此外，自2004年秋季以来，该实验室一直与圣何塞技术博物馆合作，建立一个关于“自然界中的微生物及其在水处理中的作用”的展览模块。该实验室的成员积极担任“Synopsys硅谷科学技术锦标赛”、“改变女孩”和辅导东帕洛阿尔托高中学生的评委。 这些活动将在整个当前项目中继续进行。拟议研究的预期意义本研究旨在利用S. oneidence作为一个模型系统。此外，研究结果也将为应用环境和医学领域管理微生物生物膜提供有用的依据。例如，通常需要防止或控制有益于废水和地下水处理的生物膜的溶解，而管道、船舶的腐蚀以及牙齿（龋齿）、龈下袋和导管上医学上有害的生物膜的形成可以通过微生物分离生理学的工程操纵来减轻（或防止）。因此，本研究不仅具有理论意义，而且具有应用价值。

Intellectual MeritMost microbes in nature are believed to exist in biofilms that develop on biotic or abiotic surfaces at almost any aqueous interface. These surface-associated, structured microbial communities are of medical and environmental importance. Stability and resilience of mature biofilms is controlled by two interrelated cellular processes: attachment and detachment. However, the underlying molecular mechanism(s) of detachment and attachment are largely unknown. This project explores the first steps towards a physiological, genetic and biochemical understanding of the detachment/attachment processes. Shewanella oneidensis MR-1, a geochemically important microbe that metabolically interacts with Fe- and Mn-containing soil minerals in biofilms serves as model microbe for these studies. The multi-tiered approach involves physiological studies on detachment including energetic and cell mixing experiments. The results expected from this research should provide fundamental insights into the molecular mechanism(s) of microbial detachment from biofilms. While the initial processes of biofilm formation have been investigated in the past, the important questions of the control of stability of established biofilms and their long-term survival have not been addressed. These studies will reveal some important physiological, mechanistic, and genetic principles of determining biofilm stability.Broader ImpactThis research will generate fundamental knowledge on the biology of microbial biofilms and educate graduate and undergraduate students and the broader community. This laboratory has a record of attracting and retaining minorities (70% of the lab are female, 33% ethnic minority). The PI teaches on an annual basis three courses in Environmental Microbiology including a new sophomore seminar on "Environment and Human Health." The broader impact of the activities of the entire lab is on several levels. The PI served for the last four years as co-director of the MBL "Microbial Diversity Course" in Woods Hole, MA; served 2003/04 as a member on the NRC/NAS committee on "Alternatives and Strategies for Future Use and Production of Hydrogen"; the PI has been on the scientific advisory board of Sound Vision for the production of "The DNA Files"; has served since 2000 as the director of the Stanford Biofilm Research Center, since 2002 as co-organizer of the annual "West Coast Bacterial Physiologists' Meeting", Asilomar, CA; and since 2003 as the program coordinator of Stanford's Environmental Engineering and Science Program. In addition, since the fall of 2004, this laboratory has been working with the San Jose Museum of Technology to establish an exhibition module on "Microbes in Nature and their Role in Water Treatment". Members of this laboratory have been active as judges in the "Synopsys Silicon Valley Science and Technology Championship", in "Girls for a Change", and in tutoring East Palo Alto High School students. Activities such as these will continue throughout the current project.Expected significance of proposed researchThis research seeks to provide a physiological and molecular understanding of microbial attachment, detachment, and the transitioning between both states using S. oneidensis as a model system. In addition, the results will also serve as a useful basis for the applied environmental and medical fields to manage microbial biofilms. For example, the dissolution of biofilms beneficial for wastewater and groundwater treatment often needs to be prevented or controlled, whereas corrosion of pipes, ships, as well as formation of medically detrimental biofilms on teeth (caries), subgingival pockets, and catheters could be mitigated (or prevented) by engineered manipulation of the microbial detachment physiology. Therefore, this research is not only of fundamental but also applied relevance.