| |
| |
|
|
|
|
| |
 |
Nitrogen cycling in the ocean: From genes to ecosystems and from the past to the future
|
| |
|
|
Comparative genomics and evolutionary analyses of marine ammonia-oxidizing archaea
Monday 7th @ 1130-1150, Multifunction Hall
Wei Qin* , University of Washington, School of Oceanography, Seattle, USA
Yue Zheng, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
Feng Zhao, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
David A. Stahl, University of Washington, Department of Civil and Environmental Engineering, Seattle, USA
Anitra E. Ingalls, University of Washington, School of Oceanography, Seattle, USA
Presenter Email: qinwei2010@gmail.com |
| Marine ammonia-oxidizing archaea (AOA) are a diverse group that forms a monophyletic clade within the Thaumarchaeota. They are essential and abundant microorganisms in the ocean due to their role in regulating the nitrogen cycle, contributing to the dark ocean carbon fixation, and supplying vitamin B12 to B12-dependent organisms. Although marine AOA provide the foundation for the function and stability of marine ecosystems, we still have very limited understanding about their incredible genetic diversity and associated high adaptive capacity. To test the extent to which genotypic differences translate to phenotypic variation among AOA, we compared the whole-genomes of 45 AOA species across diverse geographic locations. Comparative analysis revealed extensive gene content diversity among these genomes. The pan-genome analysis of Nitrosopumilus-like marine AOA indicated that the degree of openness of their pan-genome is comparable or even slightly higher than those of the other two globally widespread marine microorganisms, SAR11 and Prochlorococcus. In addition, since the isolation of N. maritimus SCM1 in 2005, this strain has been continuously transferred under optimum growth condition. We monitored the evolution process of N. maritimus along the ~3000 generations of continuous transferring, and identified the mutations underlying their adaptive growth. Following ~1200 generations of continuous culturing of N. maritimus under optimum growth condition in the lab, the glycine residue near the Cu binding site of nitrite reductase was mutated. This mutation is associated with an enhanced growth rate and different production rate of nitric oxide, a key intermediate in the ammonia oxidation pathway. Together, these findings highlight a significant genetic reservoir in marine AOA, which confers selective advantages for their niche-specific adaptations. |
|
|
|
|
|
|
|
|