|Place of Conferral||北京|
|Keyword||滨海湿地 河口 铁循环菌 多样性 电活性|
|Other Abstract|| 铁是滨海湿地环境中重要的变价金属元素，铁还原菌和铁氧化菌介导的铁的氧化还原过程与碳、氮等元素的循环相耦合，在生物地球化学循环过程中起到重要的驱动作用。阐明滨海湿地沉积物中铁还原菌和铁氧化菌群落结构的变化和分布特征，及其主要环境驱动因素，对于认识河海交互作用区域铁还原菌和铁氧化菌在生物地球化学循环过程中作用具有重要意义。黄河三角洲作为典型的滨海湿地，是世界上陆-河-海交互作用最活跃的区域之一。本研究以黄河三角洲滨海潮滩湿地、河口及近海沉积物为研究对象，通过对原位土壤/沉积物及其富集培养样品进行基于16S rRNA和rRNA高通量测序以及对原位样品环境因子的测定，解析了滨海区域不同空间和生态演替尺度下细菌群落组成的变化规律，及其主要环境影响因素；分析了河海交互作用区域铁还原菌和铁氧化菌群落结构组成和变化特征；揭示了潮滩湿地不同盐度植物带土壤铁还原菌和铁氧化菌群落结构差异；分离得到具有铁还原能力和电化学活性的团聚体，发现电子穿梭体蒽醌-2,6-二磺酸(AQDS)和活性炭能够明显促进团聚体的胞外电子传递；证实了Geobacteraceae和Methanosarcina mazei的共生体存在于滨海河流沉积物富集体系中。研究中得到的主要结论如下：|
5、通过对滨海河流界河沉积物样品富集培养，并基于16S rRNA/rRNA 的分子生物学方法，证实了Geobacteraceae和Methanosarcina mazei的共生体存在于界河沉积物富集体系中，并且在铁还原富集体系中具有铁还原活性和产甲烷能力。微生物种间常以团聚体的形式进行直接种间电子传递，本研究以乙醇为底物时经过3代转接培养，M. mazei和Geobacteraceae形成紧密结合的团聚体，这表明两者可能能够进行直接种间电子传递。界河沉积物富集样品中主要优势细菌和古菌分别为Geobacteraceae、Bacilli和Methanosarcinaceae。
; Iron is one of the most abundant variant valence metal elements. Iron-reducing bacteria (IRB) and iron-oxidizing bacteria (IOB) play pivotal biogeochemical roles in the coupling of iron and carbon or nitrogen redox cycles. In the coastal wetland environments, pattern in abundance, diversity of IRB and IOB can provide evidence of their contribution to biogeochemical cycles in assessing their community structural distinctions associated with spatial variations of nutrients in different habitats. As a typical coastal wetland, the Yellow River Delta is one of the most active regions of wetland-river-sea interaction in the world. In this study, spatial patterns and community structures of IRB and IOB in soil/sediment samples from the Yellow River estuary through intertidal wetland to coastal marine environments were investigated. Deep sequencing of bacterial 16S rRNA gene and rRNA in field and enrichment samples revealed significant shifts in diversity and distribution of bacterial community, iron-reducing and -oxidizing bacterial communities in sediment samples from the Yellow River estuary to Bohai Sea, and in wetland soils with different salinity gradient. The effects of biogeochemical variables along the gradient on the abundance and biogeographic patterns of bacteria, putative IRB and IOB in sediments were investigated. Aggregates with iron reduction and electrical activity were obtained. AQDS and granular activated carbon can obviously promote extracellular electron transfer for the aggregate. The co-occurrence of Geobacteraceae and Methanosarcina mazei and their activities in an iron(III)-reducing microbial community from a coastal gold mining river has been found. The main results were summarized as follows:
Differences in bacterial community composition indicate that community diversity and spatial distribution of bacteria in sediments from the typical coastal area with land-river-sea interaction are mainly determined by biogeochemistry and habitats. Yellow River sediment had the highest diversity and was dominated by hydrogen-, nitrogen- and iron-cycling bacteria, such as Hydrogenophaga, Nitrospira, Pseudomonas, and Thiobacillus. The intertidal wetland had a haloduric community with diverse function (such as Planctomyces, Marinobacter, Halomonas, Salinivibrio and Salinibacter). The Bohai Sea sediment had higher relative abundances of Lutimonas, Desulfococcus, Photobacterium, Propionigenium, and Vibrio. Salinity, pH and SO42- concentration were key parameters, which contributed to variations in the bacterial communities.
Relative abundance of IRB and IOB in samples from intertidal wetland with different salinity gradients showed distinct responses to salinity, revealing considerable spatial heterogeneity even within this relatively small site.. The diversity of iron-reducing bacterial populations was negatively correlated with soil salinity, while the diversity of iron-oxidizing bacterial populations was positively correlated with soil salinity. Iron-reducing bacteria Geobacter, Pseudomonas, Thiobacillus, Bacillus and Anaeromyxobacter, together with iron-oxidizing bacteria Gallionella and Thermomonas species were predominanted in soil samples with low salinity (Blendimings and Phragmites), respectively, whereas Bacillus, Desulfovibrio, Clostridum and Marinobacter species were the dominant iron-reducing and -oxidizing bacteria in soil samples with high salinity (Suaeda and Tamarix), respectively. Soil samples with low salinity have higher activity of iron(III) reduction.
Change in relative abundance and spatial distribution of iron-reducing and -oxidizing bacterial communities in sediment samples from the Yellow River estuary to Bohai Sea, revealed substantial spatial heterogeneity between two ecosystems. Community diversity and spatial distribution of the IRB and IOB in sediments from the typical coastal area with river-sea interaction are mainly determined by biogeochemical factors and habitat type. Relative abundance and diversity of IRB and IOB in sediments from the Yellow River estuary were higher than those from the Bohai Sea. We found that Pseudomonas, Thiobacillus, Geobacter, Rhodoferax, Clostridium and Azospira, Gallionella, Rhodobacter, Thermomonas were the most abundance genera of IRB and IOB in sediments from the Yellow River estuary. And the dominant genera in sediments from the Bohai Sea were Vibrio, Shewanella, Thiobacillus and Marinobacter. The opposite trend was observed in enrichment cultures compared to in situ samples, indicating that relative abundance of IRB in marine sediments can be promoted in the presence of amorphous iron oxides in enrichment culture. However, sediment samples from river have higher activity of Fe(III) reduction than those from marine. Shifts in diversity of putative iron-reducing, iron-oxidizing and nitrogen-cycling bacteria discovered a novel distribution pattern in Yellow River estuary and adjacent Bohai Sea. There are the higher relative abundances and diversities of putative iron-reducing, iron-oxidizing and nitrogen-cycling bacteria at coastal transitional sites. Relative abundance of well-known nitrogen-cycling bacteria was positively correlated with relative abundance of iron-cycling bacteria. Additionally, concentrations of TN, NH4+-N and NO3--N contributed to variations of iron-reducing and -oxidizing bacterial communities.
Aggregate C1 with iron reduction activities formed by Desulfovibrio and Pseudomonas was isolated from coastal wetland. Differences in relative abundances of Desulfovibrio and Pseudomonas in aggregate C1 were observed when offered with different types of organic substrates. The effect of salinity on Fe (III) reduction of aggregate C1 was little in cultures with ethanol as the only electron donor. AQDS and granular activated carbon can obviously promote electron transfer between aggregate C1 and Fe (III) oxide. Aggregate produced higher electrical density in microbial fuel cell with dialysis bag, revealing it may use electron shuttle for extracellular electron transfer.
The co-occurrence of Geobacteraceae and Methanosarcina mazei and their activities in an iron(III)-reducing microbial community from a coastal gold mining river, Jiehe River, has been found and confirmed by culture independent molecular techniques based on 16S rRNA and rRNA, respectively. Aggregates, as close physical contact necessary for direct interspecies electron transfer (DIET), have been found in the culture with ethanol as electron donor after three transfers, and indicated the possibility of DIET between them. The enrichment cultures actively contained the bacteria belong to Geobacteraceae and Bacilli, exclusively dominated by the archaea belong to Methanosarcinaceae.
|First Author Affilication||Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences|
|张洪霞. 黄河三角洲滨海湿地铁循环微生物多样性和电活性[D]. 北京. 中国科学院大学,2017.|
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