| Global warming caused by excessive CO2 emission impacts on global ecological environment and human development. Microbial CO2 fixation by micro alage has received great attention with advantages of low energy consumption, non-pollution and resource utilization of CO2. But cultivation of micro alage require light, cannot resist high concentration of CO2 and also require huge culture area. Therefore, it is necessary and significant to isolate highly efficient CO2 fixing microorganisms that do not require light to enable a wider range of applications. The Ocean is the largest carbon pool in the world, also it’s the largest microorganism sink. There are abundant autotrophic micororganisms resource in the ocean due to its barren and various environments.Previous research had isolated and enriched non-photosynthetic microbial community (NPMC) from some area of the coastal surface seawater. Also, with optimizing of electron donor system, the efficiency of carbon fixation by NPMC was greatly improved. However, as the ocean is widely distributed in the world, the geological environments and natural conditions are different and diverse. Particularly, natural environments are greatly varied in different depths of the sea. The NPMC’s structures of different area and depth in the ocean might be different and distributions of carbon fixation gene (CFG) and potential CO2 fixation capability (PCFC) of NPMC in response to different electron donors also might be varied. Nevertheless, related studies about distributions of CFG and PCFC of NPMC in different area and depth of the ocean have not been released so far.In the experiment, the seawaters collected from the South China Sea in 2013 by the west of the South China Sea open voyage (Voyage No. NORC2013-07) supported by NSFC were studied in order to explore space distribution pattern of main CFG and PCFC of NPMC. Meanwhile, the possible reasons of the distribution pattern of main CFG and PCFC of NPMC were analyzed and discussed. The results are as follows:(1) Distribution of main CFG are diversified from each other in different area’s surface seawater, area A (18°N-20°N,110°E-113°E) with highest CFG abundance while area B (15°N-17°N,110°E～112°E) and area C (15°N-17°N,112°E-114°E) with the lowest CFG abundance. Area D(12°N-15°N,110°E-112°E), E(12°N-14°N, 112°E-114°E), F(approximate 10°N,1130E-114°E)are almost equal. The variability in total bacterial quantity in different areas may be the key element leads to the CFG distribution pattern.(2) The response of PCFC of NPMC in different area to H2, Na2S2O3 as electron donors respectively are different. When using H2 as electron donors, PCFC of NPMC in area B is the highest while area C is the lowest. PCFC of area D, E are higher than A, F. When using Na2S2O3 as electron donors, PCFC of NPMC from area A, B, E, F are almost equal and D is the highest, C is the lowest. Diversity of microbal community structure in seawater is the key element leads to the distribution pattern of PCFC.(3) Main CFG cbbL abundance in surface seawater is higher than deep seawater while cbbM gene abundance in deep seawater is higher than in surface seawater. The variability in microbal community structure in seawater with different depths is the primary cause leads to diverse distribution of CFG.(4) PCFC of NPMC in surface seawater is higher than deep seawater while using H2 as electron donor, on the contrary, PCFC of NPMC in deep seawater is higher than surface seawater while using Na2S2O3 as electron donor. Diversity of microbal community structure and CFG abundance are the key elements to these differences.Summary, there are differences in space distributions of main CFG and PCFC. However distributions of CFG and PCFC are not in corresponding with each other, this might be related with NPMC’s structure.The culturiability of marine bacteria with cbbs are different. Paracoccus is easy to be cultured using H2 as electron donor, and the area with higher abundance of Paracoccus is likely to enrich NPMC with higher PCFC from it. |
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