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

锰(Mn)氧化微生物通过将可溶的Mn(II)氧化成难溶的Mn(III，IV)氧化物，在全球Mn的生物地球化学循环中起着不可或缺的作用。除了锰以外，这些微生物还会影响其他金属、硫和碳的命运，因此可以用于生物修复。这些微生物在锰循环之外的影响是由于锰(II)氧化形成的生物锰氧化物非常活跃和吸附的结果。尽管氧化微生物对生物地球化学循环具有重要的影响，但在细胞和分子水平上，我们对微生物如何以及为什么氧化锰(II)知之甚少。最近确定了一种新的过氧化物酶，用于氧化α-变形杆菌中的Mn(II)。这种新的锰(II)氧化酶提出了关于这一过程以及这种独特的酶可能如何发挥作用的问题。由于从天然来源获得纯化的锰(II)氧化蛋白极其困难，阻碍了对任何类型的Mn(II)氧化蛋白的机理的理解。因此，本项目将在大肠杆菌中异源表达该蛋白，并对这一新的锰(II)氧化蛋白进行鉴定。对这种新酶的了解将有助于我们深入了解Mn(II)的氧化机制，并将拓展我们对生物化学多样性和蛋白质功能的看法。该项目还调查了细菌氧化锰(II)的原因。这项研究将确定氧化锰是否提供细胞保护并影响细胞内的锰浓度。总之，这些研究将改变我们对锰(II)氧化作为一种重要的生理和生物地球化学过程的看法。更广泛的影响锰(II)氧化细菌产生的锰氧化物在金属和有机污染场地的生物修复中可以发挥重要作用。了解细菌如何以及为什么氧化Mn(II)有可能更好地控制这一过程，增加其适用性。研究将主要由本科生进行。学生们将进行合作，并将被鼓励在地方和国家会议上发表和展示他们的成果。这些项目为学生在地球微生物学、生物化学和生物技术方面提供了极好的培训机会。跨学科培训将培养出准备在生物技术行业、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，对代表不足的学生的培训将是该项目不可或缺的一部分。

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.