Microbial Genome Sequencing: The Complete Genome Sequence of a Mini Consortium of Marine Ammonia Oxidizers

氨在海洋、淡水、土壤和大气中含量丰富，是微生物和植物可用氮的主要来源，微生物和植物通过消费为动物提供氮。另一方面，氨被认为是我们呼吸的空气中随处可见的最丰富的神经毒素。因此，理解氨的自然消耗机制是维持一个适宜居住的地球的关键。路易斯维尔大学的Martin G.Klotz博士与基因组研究所的John Heidelberg博士、伍兹霍尔海洋研究所的Karen Casciotti博士和普林斯顿大学的Bess Ward博士合作，对海洋氮循环中的两种变形杆菌的完整基因组进行了测序。这两种细菌在海洋中执行类似的生态生理功能，即将氨转化为亚硝酸盐，并产生含氮气体，这些气体最终将被循环利用为无害的氮气。这两个被研究的海洋细菌在分类上属于不同的细菌类别，因此它们的基因组可能包含不同的硝化活动的分子基础。因此，这些细菌遗传组成的揭开将为我们提供大量的洞察，使我们了解这些细菌在数十亿年的时间里进化出的能够降解氨的分子机制的多样性。将这一复杂的基因组信息与在淡水或土壤中起作用的氨氧化剂的基因组信息进行比较，将使未来的科学项目能够设计改进的技术战略，以控制人类活动产生的氨的去除，并确定控制这种氨氧化细菌的目标，在这些细菌存在的地方(如饮用水生产设施)。通过这笔补助金资助的工作将涉及本科生和研究生的培训。

Ammonia is abundant in the oceans, in freshwater, soils and the atmosphere and represents the prime resource of usable nitrogen for microorganisms and plants, which provide nitrogen to animals through their consumption. On the other hand, ammonia is considered the most abundant neurotoxin that is present everywhere in the air that we breathe. Therefore, the understanding of mechanisms naturally involved in the consumption of ammonia is key to maintaining a hospitable planet Earth. A grant has been awarded to Dr. Martin G. Klotz of the University of Louisville, in collaboration with Drs. John Heidelberg of The Institute for Genome Research, Karen Casciotti of the Woods Hole Oceanographic Institute, and Bess Ward of Princeton University, to sequence the complete genomes of two proteobacteria that are key players in the marine nitrogen cycle. Both bacteria carry out a similar ecophysiological function in the oceans namely the conversion of ammonia to nitrite and the production of nitrogenous gases that - eventually - will be recycled to benign nitrogen gas. The two researched marine bacteria belong taxonomically to different classes of bacteria; hence their genomes likely contain different molecular bases for nitrification activities. Thus, the unraveling of the genetic make-up of these bacteria will provide us a great deal of insight into the diversity of molecular mechanisms capable of ammonia degradation that have evolved over billions of years in these bacteria. A comparison of this complex genomic information with that from ammonia-oxidizers that function in freshwater or soils will allow future scientific projects to design improved technological strategies for controlled removal of ammonia generated by human activities as well as the identification of targets for the control of such ammonia-oxidizing bacteria where their presence is undesirable (such as in drinking-water production facilities). Work funded through this grant will involve the training of undergraduate and graduate students.