太平洋不同生境深海真菌的多样性、生态分布特征及其反硝化能力研究

真菌作为海洋生态系统的重要成员，其在深海环境中的群落结构与生态功能的认识还十分有限。反硝化作用是氮循环的一个重要环节，之前普遍认为是由原核生物主导。近来的研究表明，真菌也具有反硝化能力，对反硝化的贡献不可忽视。然而，当前对于深海环境中真菌的多样性及其反硝化能力还知之甚少。本项目拟针对三种不同深海生境（深海平原、海山、海沟），通过分离培养与高通量测序手段结合，研究不同生境真菌多样性的区别，并结合统计学分析，认识真菌在深海不同生境的生态分布特征，明确影响深海真菌生态分布的关键环境因子。同时通过真菌反硝化功能基因的克隆测序分析与深海样品直接反硝化培养相结合，认识深海不同生境反硝化真菌的多样性及对反硝化的贡献，并通过深海纯培养菌株产N2O能力的测定，了解不同种属深海真菌反硝化能力的强弱。研究结果对于深入认识深海不同生境真菌的多样性、生态分布特征以及真菌在深海氮循环过程中的参与度与贡献具有重要意义。

Fungi are an important component of marine ecosystem. However, the information of community composition and ecological function of fungi in deep sea environment remains scarce. Denitrification is an important process in the global nitrogen cycle and is considered to be mainly mediated by prokaryocytes. However, recent studies showed that fungi are also capable of denitrification. The contribution of fungi to denitrification cannot be ignored. However, the current knowledge on fungal diversity in deep sea environment and their denitrifying activity is still very limited. Therefore, this project focuses on three different deep sea habitats (deep sea floors, sea mountains, and deep sea trenches) and investigates diversity of fungi in different deep sea habitats based on cultivation method combined with high throughput sequencing method. Ecological distribution of fungi in different deep sea habitats was also investigated based on statistical analysis, in order to identify key environmental factors influencing ecological distribution of deep sea fungi. Meanwhile, diversity of denitrifying fungi in different deep sea habitats was investigated based on fungal denitrifying functional gene sequencing; fungal contribution to denitrification process in deep sea environment was also assessed by denitrification incubation of deep sea samples in microcosoms. In addition, N2O-prducing activity of deep sea culturable fungi was investigated to estimate the denitrification ability of different fungal genera. The results will contribute to understanding the diversity and ecological distribution of fungi in different deep sea habitats, as well as the contribution of deep sea fungi to marine nitrogen cycle.