Microaerobic Fe (Ⅱ) oxidation coupled to carbon assimilation processes driven by microbes from paddy soil

作     者：Xiaomin LI Shan MOU Yating CHEN Tongxu LIU Jun DONG Fangbai LI 

作者机构：SCNU Environmental Research InstituteGuangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety&MOE Key Laboratory of Environmental Theoretical ChemistrySouth China Normal UniversityGuangzhou 510006China Guangdong Key Laboratory of Integrated Agri-Environment Pollution Control and ManagementGuangdong Institute of Eco-Environmental Science&TechnologyGuangzhou 510650China School of Micro-Electronics and Solid-State ElectronicsUniversity of Electronic Science and Technology of ChinaChengdu 610054China Institute for Disaster Management and ReconstructionSichuan University-Hong Kong Polytechnic UniversityChengdu 610207China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2019年第62卷第11期

页      面：1719-1729页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41571130052, 41701295 & 41271263) the Guangdong Natural Science Funds for Distinguished Young Scholars (Grant No. 2017A030306010) 

主　　题：Microaerobic Fe(Ⅱ)oxidation Paddy soil Carbon assimilation Microorganism 

摘      要：Microaerobic Fe(Ⅱ) oxidation process at neutral pH, driven by microbes can couple to carbon assimilation process in iron-rich freshwater and marine environments;however, few studies report such coupled processes in paddy soil of the critical zone in South China. In this study, rhizosphere soil from flooded paddy field was used as the inoculum to enrich the microaerophilic Fe(Ⅱ)-oxidizing bacteria(FeOB) in gradient tubes with different Fe(Ⅱ) substrates(FeS and FeCO_3) and ^(13)C-biocarbonate as inorganic carbon source to track the carbon assimilation. Kinetics of Fe(Ⅱ) oxidation and biomineralization were analyzed, and the composition and abundance of the microbial community were profiled using 16 S rRNA gene-based highthroughput sequencing. Results showed that microbial cell bands were formed 0.5–1.0 cm below the medium surface in the inoculated tubes with Fe(Ⅱ) substances, while no cell band was found in the non-inocula controls. The protein concentrations in the cell bands reached the highest values at 18.7–22.9 mg m^L(-1) on 6 d in the inocula tubes with Fe(Ⅱ) substrates. A plateau of the yields of ^(13)C-biocarbonate incorporation was observed during 6–15 d at 0.44–0.54% and 1.61–1.98% in the inocula tubes with FeS and FeCO_3, respectively. The inocula tube with FeS showed a higher Fe(Ⅱ) oxidation rate of 0.156 mmol L^(-1) d^(-1) than that with FeCO_3(0.106 mmol L^(-1) d^(-1)). Analyses of X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy revealed that amorphous iron oxide was formed on the surface of rod-shaped bacteria after Fe(Ⅱ) *** to the agar only control, the abundances of Clostridium and Pseudogulbenkiania increased in the inocula tube with FeS,while those of Vogesella, Magnetospirillum, Solitalea, and Oxalicibacterium increased in the inocula tube with FeCO_3, all of which might be the potential microaerophilic FeOB in paddy soil. The findings in this study suggest that microbes that couple micro