Fixation of carbon dioxide by chemoautotrophic bacteria in grassland soil under dark conditions
Fixation of carbon dioxide by chemoautotrophic bacteria in grassland soil under dark conditions
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DOI：
10.1080/09064710.2017.1281433
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
Jun Yang;Yumei Kang;K. Sakurai;K. Ohnishi
中科院分区：
文献类型：
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作者：
Jun Yang;Yumei Kang;K. Sakurai;K. Ohnishi
摘要草地是陆地生态系统中碳、氮循环的重要组成部分。然而，虽然光合细菌固定CO2的研究相对较好，很少有人知道微生物CO2固定没有光的草原土壤中的化能自养细菌。因此，本研究利用同位素14 C-CO2研究了草原土壤中CO2的固定过程。从内蒙古围栏和相邻的连续放牧草地上采集土壤样品，然后在黑暗条件下培养120天。同时，cbbL基因（红色和绿色）进行了分析，以分离化能自养细菌，这是负责CO2固定。培养后，围栏和放牧土壤中均存在14 C固定到土壤有机碳（14 C-SOC）和微生物量碳（14 C-MBC）中，围栏土壤14 C-SOC的固定率（48.55‰）显著高于放牧土壤（22.11‰）。围栏土壤对14 C-MBC的固定率（14.05‰）高于放牧土壤（7.08‰），但差异不显著。在所有的土壤样品中都能检测到类红色的cbbL基因，而类绿色的cbbL基因则没有被扩增出来。围栏土壤中的操作分类单位的数量比放牧土壤中的数量更多。化能自养细菌主要隶属于α-变形菌门和放线菌门。然而，仅在围栏土壤中检测到绿弯杆菌。结果表明，化能自养细菌对CO2的固定在草地碳循环中具有重要意义。
ABSTRACT Grassland is one of the most important terrestrial ecosystems for carbon (C) and nitrogen (N) cycling. However, while CO2 fixation by phototrophic bacteria is relatively well studied, little is known about microbial CO2 fixation without light by chemoautotrophic bacteria in grassland soils. Therefore, in this study, the isotope 14C-CO2 was used to investigate the CO2-fixing process in grassland soils. Soil samples were collected from both fenced and adjacent continuous grazing grassland sites in Inner Mongolia and then incubated for 120 days under dark conditions. Meanwhile, the cbbL genes (red- and green-like) were analyzed to isolate chemoautotrophic bacteria, which are responsible for CO2 fixation. After incubation, 14C was fixed into soil organic carbon (14C-SOC) and microbial biomass carbon (14C-MBC) were found in both the fenced and grazing soils, and the fixation rate of 14C-SOC in the fenced soils (48.55‰) was significantly higher than in the grazing soils (22.11‰). The fixation rate of 14C-MBC in the fenced soils (14.05‰) was higher than in the grazing soils (7.08‰), but the difference was not significant. The red-like cbbL genes could be detected in all the soil samples, but the green-like cbbL genes could not be amplified. A greater number of identified operational taxonomic units were observed in the fenced soils compared with the grazing soils. The chemoautotrophic bacteria were mainly affiliated with Alphaproteobacteria and Actinobacteria. However, Chloroflexi was detected in only the fenced soils. The results suggested that CO2 fixation by chemoautotrophic bacteria might be significant in carbon cycling in grassland.