RIG: The Physiological Significance of Microbial Mn(II) Oxidation

锰（Mn）氧化微生物通过将可溶性锰（II）氧化为不溶性锰（III，IV）氧化物，在锰的全球生物地球化学循环中发挥着不可或缺的作用。除了锰，这些微生物还影响其他金属、硫和碳的命运，因此可以用于生物修复。这些微生物在Mn循环之外的影响是由于Mn（II）氧化形成的生物源Mn氧化物具有非常活跃的吸附特性。尽管Mn（II）氧化微生物可以对生物地球化学循环产生重要影响，但我们在细胞和分子水平上对微生物氧化Mn（II）的方式和原因知之甚少。一种新的过氧化物酶最近被确定在α变形菌中氧化Mn（II）。这种新的锰（II）氧化酶提出了有关这一过程以及这种独特酶如何发挥作用的问题。从天然来源获得纯化的Mn（II）氧化蛋白非常困难，这阻碍了对任何类型Mn（II）氧化蛋白机制的理解。因此，本项目将在大肠杆菌中异种表达该蛋白并对其进行鉴定。对这种新酶的理解将提供对Mn（II）氧化机制的必要见解，并将扩大我们对生化多样性和蛋白质功能的看法。该项目还研究了细菌氧化Mn（II）的原因。该研究将确定锰氧化物是否提供细胞保护并影响细胞内锰浓度。总之，这些研究将改变我们对锰（II）氧化作为一个重要的生理和生物地球化学过程的看法。广泛的影响Mn（II）氧化细菌产生的Mn氧化物在金属和有机污染场地的生物修复中发挥重要作用。了解细菌氧化Mn（II）的方式和原因有可能更好地控制这一过程，增加其适用性。这项研究将主要由本科生进行。学生们将协同工作，并鼓励他们在地方和国家会议上发表和展示他们的成果。这些项目是学生在地球微生物学、生物化学和生物技术方面极好的训练机会。跨学科的培训将培养出在生物技术行业、研究生院或卫生专业学校取得成功的学生。加州州立大学是一所西班牙裔服务机构，对代表性不足的学生的培训将是这个项目的一个组成部分。

Manganese (Mn) oxidizing microbes play an integral role in the global biogeochemical cycling of Mn by oxidizing soluble Mn(II) to insoluble Mn(III,IV) oxides. Beyond Mn, these microbes affect the fate of other metals, sulfur, and carbon and therefore can be used in bioremediation. The influence of these microbes beyond the Mn cycle is a result of the very reactive and adsorptive properties of biogenic Mn oxides formed by oxidation of Mn(II). Despite the important influence Mn(II) oxidizing microbes can have on biogeochemical cycles, we know very little on the cellular and molecular level about how and why microbes oxidize Mn(II). A new peroxidase enzyme was recently determined to oxidize Mn(II) in alpha proteobacteria. This new Mn(II) oxidizing enzyme raises questions about the process as well as how this unique enzyme may function. Understanding the mechanism of any type of Mn(II) oxidizing protein has been hindered by the extreme difficulty in obtaining purified Mn(II) oxidizing proteins from native sources. Therefore, this project will heterologously express this protein in Escherichia coli and characterize this new Mn(II) oxidizing protein. An understanding of this new enzyme will provide needed insight into the mechanism of Mn(II) oxidation and will expand our view of biochemical diversity and protein function. This project also investigates why bacteria oxidize Mn(II). The research will determine if Mn oxides provide cellular protection and affect intracellular manganese concentrations. Together, these studies will transform our view of Mn(II) oxidation as an important physiological as well as biogeochemical process.Broader ImpactsThe Mn oxides produced by Mn(II) oxidizing bacteria can play an important role in bioremediation of metal and organic contaminated sites. Understanding how and why bacteria oxidize Mn(II) has the potential to better control this process, increasing its applicability. The research will be performed primarily by undergraduate research students. The students will work collaboratively and will be encouraged to publish and present their results at local and national meetings. These projects are excellent training opportunities for students in geomicrobiology, biochemistry, and biotechnology. The interdisciplinary training will yield students ready to succeed in the biotechnology industry, graduate school, or a health professional school. California State University is a Hispanic serving institution and training of underrepresented students will be an integral part of this project.