|  |
Program |
 |
| |
 |
Special Session 4: Biogeochemical cycling of trace elements in the ocean: GEOTRACES and beyond |
| |
|
|
Responses of trace element composition to the growth and metabolism of marine micro - organisms and its marine ecological significance
SS4-12-S
Chenhe Zheng* , State Key Lab of Marine Environmental Science(Xiamen University)
Deli Wang, State Key Lab of Marine Environmental Science(Xiamen University)
Yan Jiang, State Key Lab of Marine Environmental Science(Xiamen University)
Kai Tang, State Key Lab of Marine Environmental Science(Xiamen University)
Yujie Yang, State Key Lab of Marine Environmental Science(Xiamen University)
Dan Lin, State Key Lab of Marine Environmental Science(Xiamen University)
Presenter Email: chenhe519@stu.xmu.edu.cn
|
| Trace metals are essential in marine biology, and especially metals including Fe, Mn and Mo play a key role in photosynthesis, electron transfer, organic respiration and carbon fixation. However, previous studies mainly focused on marine phytoplankton, and there is still little information available regarding its relationships with marine bacteria growth and its interactions with bacteria and algae from the chemical quantification point of view. Until so far, we are lack of any information of its variation in cellular concentrations in response to environmental changes. We combined the cultivation experiment and the field investigation, and conducted a series of cultures by using a sulfur oxidizing bacteria (which was isolated from deep sea water near the East Pacific Rise) under autotrophic (bicarbonate is used for carbon source) vs heterotrophic (glucose for carbon source) stages. We chose Taiwan Guishantao hydrothermal area for field investigation area. We analyzed the distribution of trace elements and the composition of bacterial community, and combined with the mesoscale culture experiment in Wuyuan Bay, which aimed to explore the significance of trace elements for micro-organism metabolism and the marine ecology. The samples were collected for analyzing dissolved metals, cellular metals, and bacterial growth and physiological parameters.
The results demonstrated that bacteria absorbed dissolved metals from ambient waters quickly at the initial stage. The cellular concentrations of metals were also quite different between autotrophic and heterotrophic stages: higher in autotrophic stage than in heterotrophic stage. In particular, we observed a departure (a decrease) of cellular concentrations from the abundance dilution line at the early exponential growth phase, indicating of an excretion of trace metals from cells, although its mechanism is still not clear. Cellular concentrations of metals in bacteria are significantly higher than those in marine phytoplankton reported by previous researchers (Autotrophic stage: Mo, Fe, Cu, were 13, 1524, and 160 ¦ÌM respectively, >5 times as that in marine phytoplankton; cell volume is estimated at about 0.29 ¦Ìm3 according to the SEM images). Such a significant difference could be attributed to the fact that autotrophic bacteria required more metals in Sox, and ATPase. Further investigations are needed for its ecological role, and its linking with biological evolution.
|
|
|
|
|