东海北部滨海湿地铁氧化细菌的分布及其对不同氧气穿透深度的响应

Distribution of Fe-oxidizing bacteria in the coastal wetland of the northern East China Sea and their responses to variations in oxygen penetration depth

摘要:

【目的】滨海湿地生态系统位于淡水与海水交互地带，含有高浓度Fe²⁺的地下水渗透到沉积物表层形成的湿地径流和周期性潮汐淹水形成的含氧-缺氧界面有利于铁氧化细菌介导的Fe²⁺的生物氧化过程发生。然而，目前缺乏对滨海湿地生态系统中铁氧化细菌类群的全面评估。【方法】以上海崇明西沙湿地公园及浙江舟山市朱家尖岛东沙沙滩两地共5处滨海湿地沉积物为研究对象，分析沉积物的氧气穿透深度等环境参数，并基于16S rRNA基因扩增子测序技术，全面解析不同滨海湿地生态系统中细菌与铁氧化细菌的群落组成与分布特征。【结果】与崇明西沙湿地相比，朱家尖岛东沙沙滩有更深的氧气穿透深度，达到10 mm以上。非度量多尺度分析(non-metric multidimensional scaling, NMDS)统计结果表明，细菌群落结构主要受到区域位置不同导致的环境条件差异的影响，而铁氧化细菌的群落结构则受到采样的区域位置和沉积物氧气穿透深度的共同影响。崇明西沙湿地和朱家尖岛东沙沙滩的优势细菌为蓝细菌门(Cyanobacteria)、γ-变形菌纲(Gammaproteobacteria)、拟杆菌门(Bacteroidetes)、α-变形菌纲(Alphaproteobacteria)和放线菌门(Actinobacteria)；优势铁氧化细菌为嘉利翁氏菌属(Gallionella)、红细菌属(Rhodobacter)、Lepthothrix和Sideroxydans。【结论】通过对崇明西沙湿地和朱家尖岛东沙沙滩沉积物中栖息的铁氧化菌的调查发现，铁氧化细菌的群落组成与湿地沉积物类型导致的氧气穿透深度差异具有密切联系。

Abstract:

[Objective] Coastal wetland ecosystems, situated at the interface of freshwater and seawater, are characterized by the seepage of groundwater with high Fe²⁺ concentrations into the surface layers of sediments, which forms wetland runoff. This runoff, combined with periodic tidal flooding, creates an oxic-anoxic interface conducive to the bio-oxidation of Fe²⁺ by Fe-oxidizing bacteria. However, there is a lack of comprehensive assessment of Fe-oxidizing bacterial communities in coastal wetland ecosystems. [Methods] We measured the basic environmental parameters such as the oxygen penetration depth in the sediments of five coastal wetland sites in Xisha Wetland Park in Chongming, Shanghai and Dongsha Beach in Zhujiajian Island in Zhoushan, Zhejiang. The community composition and distribution of bacteria and Fe-oxidizing bacteria were comprehensively deciphered by 16S rRNA gene amplicon sequencing. [Results] Dongsha Beach in Zhujiajian Island exhibited deeper oxygen penetration (reaching more than 10 mm) than Xisha Wetland in Chongming. The non-metric multidimensional scaling (NMDS) results indicated that the bacterial community structure was primarily influenced by environmental conditions that varied with geographical location, while the community structure of Fe-oxidizing bacteria was influenced by both the geographical location of the sampling sites and the oxygen penetration depth of the sediments. The dominant bacteria in Xisha Wetland and Dongsha Beach were Cyanobacteria, Gammaproteobacteria, Bacteroidetes, Alphaproteobacteria, and Actinobacteria. The dominant genera of Fe-oxidizing bacteria were Gallionella, Rhodobacter, Lepthothrix, and Sideroxydans. [Conclusion] We studied the Fe-oxidizing bacteria in the sediments of Xisha Wetland in Chongming and Dongsha Beach in Zhujiajian Island and discovered that the composition of Fe-oxidizing bacterial communities was closely linked to the oxygen penetration depth variations caused by different types of wetland sediments.