Abstract:

Heterotrophic bacteria play a crucial role in regulating carbon cycle in oceans, where the inventory of dissolved organic matter (DOM) is approximately equal to atmospheric carbon dioxide (CO2) pool. The uptake of DOM by bacteria is a major carbon-flow pathway. DOM-microbe interactions mediate the flux of carbon through the microbial loop in oceans, the inventory of refractory dissolved organic matter in the deep ocean, and the concentration and fate of atmospheric CO2. DOM is a complex mixture of molecules with different reactivity, and heterotrophic bacteria are diverse in terms of community composition and metabolic potential in oceans. It remains unclear how DOM and bacterial metabolism interact in marine environments. In this talk, I will present the findings from filed studies on links of DOM, bacterial carbon metabolism and bacterial community composition, and how predators (protist and virus) mediate flux of carbon in the microbial loop in three representative ecosystems (e.g. a eutrophic estuary, the frontal zone in coastal waters and eddies in the oligotrophic ocean). My work emphasizes importance of oceanographic processes in regulating bacteria-mediated carbon cycle in marine environments.

Biography:

Dr. Jie Xu is currently a research professor and associate director of State Key Laboratory of Tropical Oceanography at the South China Sea Institute of Oceanology, Chinese Academy of Sciences. He received his bachelor’s and master’s degree at Zhejiang University and his PhD in Marine Environmental Science at the Hong Kong University of Science and Technology. His research interest lies in bacteria-mediated carbon cycle in oceans, as well as dynamics of nutrients and primary production. Dr. Xu serves as associate editor for Frontiers in Marine Science, guest associate editor for Frontiers in Microbiology and the editorial board for Acta Oceanologica Sinica. He is the member of Intergovernmental Oceanographic Commission Working Group to Investigating Climate Change and Global Trends of Phytoplankton in the Oceans. He served as the member of steering committee or co-organizer for several international workshops. He has been a chief scientist of NSFC shiptime sharing project on the western South China Sea cruise since 2015.

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