冲绳海槽热液区硫氧化细菌的分布特征，培养及硫氧化机制的初步研究

The oxidation of the reductive sulfur compounds has been suggested to fulfil a key role in the biogochemical cycles in hydrothermal extreme environments.. In this study, sulfur-oxidation bacteria will be enriched and isolated with sodium thiosulfate as electron donors, under aerobic and microaerobic (6% O2) conditions and different temperature, respectively. Two mediums will be used for isolation and culture. The bacteria isolated will be identified based on 16S rRNA gene sequence analysis. All strains isolated will be evaluated whether they are chemolithothrophic bacteria which have the ability of assimilation of inorganic carbon. Also the sulfur oxidation characteristics of the strains will be analysed, the results based on the change of pH. Two different pathways for thiosulphate oxidation are present. In order to obtain more insight into sulfur metabolism of sulfur-oxidation bacteria, we will use HPLC analysis and X-ray absorption near-edge structure (XANES) spectroscopy for the detection and identification of sulfur compounds in culture supernatants and bacterial cells. We will intende to identify soluble sulfur compounds that specifically occur during growth on thiosulfate. In order to understand the nanoscale and microscale mineralization process of thiosulphate on microorganism surfaces, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) will be employed. Our study will provide the basis to further understand the ecological and biogeochemical roles of sulfur-oxidation bacteria in deep-sea hydrothermal vent ecosystems.

热液环境中，微生物对各种还原态硫的氧化过程是该系统中碳和硫生物地球化学循环的关键环节，硫的微生物氧化导致多种多样的矿物形成，也是热液活动区从数量上来说最为重要的生物过程。. 由于目前受条件所限，海洋微生物成矿过程的原位实验难以开展，热液极端环境微生物的分离和纯培养相对困难，这也是制约实验室条件下成矿过程模拟研究的瓶颈。基于上述原因，本项目拟初步分离、培养冲绳海槽热液区硫氧化细菌， 并以分离的化能自养菌为研究对象，进行硫氧化细菌成矿过程的实验室模拟研究。结合生物学、地球化学、光谱学、地质学的多种先进分析测试手段，研究深海热液区硫氧化细菌对硫元素富集、矿化的过程，并考察其作用机理，为进一步解析其成矿机制提供理论基础。

热液环境中，微生物对各种还原态硫的氧化过程是该系统中碳和硫生物地球化学循环的关键环节，硫的微生物氧化导致多种多样的矿物形成，也是热液活动区从数量上来说最为重要的生物过程。. 本文选取6个深海沉积物样品，利用高通量测序技术，对冲绳海槽热液区微生物优势种群进行了研究，结果表明该区域孕育丰富的变形杆菌参与硫元素的生物地球化学循环作用，以δ、γ变形杆菌为主；我们利用不同选择培养基，在不同培养条件下对冲绳海槽热液区微生物进行了分离、培养，分离到纯化的可培养海洋微生物菌株200余株；选取在分类学地位上具有潜在新种可能性的菌株，进行一系列的生理生化实验，鉴定出4种新种海洋微生物菌株；以分离的一株亚硫酸杆菌为研究对象，进行了硫元素成矿过程的实验室模拟研究，实验结果表明该菌株可以富集硫元素并在细胞表面形成硫酸盐的矿物颗粒；本项目还研究了盐场海芽孢杆菌与大洋铁锰结核的相互作用过程, 结果表明盐场海芽孢杆菌能够促进释放铁锰结核中Fe、Mn等元素, 同时对释放出的金属离子又有富集作用, 并能够诱导新矿物的形成。. 本研究为深入了解海洋微生物生物成矿的机制提供了新的依据。