洋山深水港病毒生物多样性的宏基因组学研究

Marine viruses, accounting for approximate 93% of the total marine species, are a unique and important strategic resource on Earth. Through influencing the composition of marine communities, viruses are a major force behind biogeochemical cycles and community metabolism. They are the major manipulator of the global ecosystem. In recent years, based on state-of-the-art metagenomics technology, the United States and Europe have sampled and analyzed the diversity of marine viruses worldwide. Due to the limitations of the techniques, by contrast, only some superficial works have been performed in China. Thus far, close to nothing is known on metagenomics study of marine virus diversity in China. Without the knowledge of their diversity, it is hardly to get insight into the role of marine viruses in the global ecosystem. Accordingly, in this proposed project, metagenomics technique is considered to survey the viral biodiversity in the heavily polluted Yangshan Harbor close to Shanghai. Based on in-depth sequencing and sequence analysis, we aim at understanding of viral population and genetic diversity, phylogenetic and evolutionary relationships, genomics and functional genes, potential emerging viruses, and their relationship to the harbor water environments.

海洋病毒约占海洋总生物种类的93%，是地球上独特且重要的战略资源。它们通过调控海洋生物的种群结构而影响水体的生物地球化学循环和群体代谢，是全球生态系统的主要操纵者。近年来，欧美国家已在全球范围内对海洋病毒资源进行采集和生物多样性分析。虽然我国也开展了初步探索，但由于技术和手段等的局限性，工作的深度和广度与欧美的差距相当大。到目前为止，还没有发现有关我国海洋病毒生物多样性的宏基因组学研究，而这恰是认识海洋病毒作用的关键。针对上述问题，本项目拟在宏基因组学水平上，以水体污染严重的洋山深水港水域中的病毒为研究对象，通过对其进行深度测序及序列分析，认识病毒的种群和遗传多样性特点、系统发育和进化关系、基因组和功能基因，以及潜在的新生病毒；探讨病毒生物多样性特点与港口水体环境的关系。

洋山深水港表层水体中病毒数量无显著性差异，病毒颗粒形态十分丰富，大多数具有“头-尾”结构，且发现了新的咖啡豆状和水滴状病毒。病毒宏基因组中绝大多数dsDNA病毒是未知病毒，已知病毒序列（21.1-28.5%）主要属于有尾病毒目（Caudovirales），包括834个种。洋山港表层水体中的ssDNA病毒绝大多数未知，其多样性极其丰富，已知的ssDNA病毒主要是感染陆地动物的Circoviridae。洋山深水港水体中病毒丰富度高，其与均一度没有明显差异。气温影响水体中病毒、细菌和古菌的多样性特点，但水环境的作用更明显。项目研究结果增进对我国海洋病毒多样性的认知，同时为洋山深水港生态学研究、外来入侵生物的监测以及洋山港和周边海域生态系统的保护提供了理论基础，也为评价工程建设及海洋贸易对港口环境的影响，积累了背景资料和科学依据。