Microbial Carbon Pump in the Ocean——from Microbial EcologicalProcess to Carbon Cycle Mechanism

The ubiquitous picoplankton are major components of food webs and thus they play key roles in biogeochemical cycle and energy flow in the marine ecosystem.Thereinto,aerobic anoxygenic phototrophic bacteria(AAPB) is an important functional group with capability of harvesting light energy,and has a particular role in the ocean′s carbon cycling.By application of new methods and further innovation of related techniques,and through extensive field investigations in the Chinese coastal wasters and the three Oceans,great data sets have been set up and systemic results have been obtained on microbial processes in the ocean′s carbon and energy flows.The following are the major achievements.1) We established a new protocol as time series observation based infrared epifluorescence microscopy(TIREM) which enabled us to enumerate AAPB accurately;2) And consequently revealed the wide distribution and unexpected abundance of AAPB in coastal waters(more abundant than in oligotrophic oceanic water which was thought to be the major niche of AAPB);3) Based on the above data sets,a novel model is proposed,where bacteriochlorophyll a induced anoxygenic phototrophy and a proteiorhodopsin based proton pump are included;4) Furthermore for carbon sequestration below the surface ocean,a conceptual model of microbial carbon pump(MCP) is proposed,which is in contrast to the well known sinking flux-based biological pump.Overall,these achievements have filled several research banks in China,and lead in the international field of marine microbial ecology.