不同盐渍土生态系统中主导反硝化作用的嗜盐古菌资源及其生态调控机制

Salinized soil is a kind of reserved resource for cultivated land, in which the soil denitrifying microorganisms can cause the loss of nitrogen, hinder the recovery of soil fertility, compete the nitrate with plants, and even release the N2O. Some previous studies we performed have indicated that halophilic archaea are the dominant indigenous microorganisms in salinized soils, which might dominate the denitrification. However, the study on the ecological characteristics of denitrifying halophilic archaea has not been carried out, because of the limitation of research methods. Based on the design of specific and degenerated primer for nitrite reductase gene (nirK) and in-situ isolation of functional single cell for denitrifying halophilic archaea, this project aims to systematically study the unicellular and molecular ecological characteristics of the denitrifying halophilic archaea in salinized soil with different salt types located at the different regions of China, through Miseq high-throughput sequencing, quantitative PCR, identification of polyphasic taxonomy, denitrification substrate and product testing based on nitrogen isotope. Then through the meta analysis for the multi-data, the ecological regulatory mechanism of denitrification of halophilic archaea in different regions and salt types of saline soil was discussed. At the same time, the resource of special halophilic archaea isolates in high salt environment of saline soil was developed. This study is of great significance to evaluate the denitrification potential and relative ecological effect of saline soil, to improve the efficiency of improvement on soil fertility, develop the study coverage of denitrifying microorganisms.

盐渍土是后备耕地资源，其土壤反硝化微生物会引起氮素流失、阻碍盐渍土肥力恢复、与植物竞争硝酸盐养分、造成N2O排放。我们前期研究发现嗜盐古菌是盐渍土的优势土著菌群，可能主导其反硝化作用。但由于研究方法限制，有关盐渍土反硝化嗜盐古菌生态学相关研究尚未开展。本项目拟基于自行设计的嗜盐古菌反硝化nirK基因的特异及简并引物和嗜盐古菌功能单细胞原位分离方法，结合Miseq高通量测序、定量PCR、多相分类学鉴定、基于15N的反硝化底物和产物检测等手段，对我国不同地域分布和盐分类型盐渍土中反硝化嗜盐古菌进行单菌特性和分子生态学相结合的系统研究。最终通过对多重数据的整合分析，阐明不同地域和盐分类型盐渍土反硝化过程中嗜盐古菌生态调控机制。同时，挖掘盐渍土作为高盐极端环境所蕴含的特殊反硝化嗜盐古菌资源。本项目研究对评估盐渍土反硝化潜势及其生态效应、提高盐渍土肥力改良效率、拓展反硝化微生物研究等具有重要意义。

盐渍土是后备耕地资源，其土壤反硝化微生物会引起氮素流失、阻碍盐渍土肥力恢复、与植物竞争硝酸盐养分、造成N2O排放。嗜盐古菌是一类嗜盐的微生物，在盐湖、盐矿、盐渍土壤等高盐生态系统中广泛分布。我们前期研究发现嗜盐古菌是盐渍土的优势土著菌群，可能主导其反硝化作用。但由于研究方法限制，有关盐渍土反硝化嗜盐古菌生态学相关研究尚未开展。本项目基于自行设计的嗜盐古菌反硝基因引物和嗜盐古菌功能单细胞原位分离方法，结合Miseq高通量测序、基因组学分析、多相分类学鉴定、反硝化底物和产物检测等手段，对我国不同地域分布和盐分类型盐渍土中反硝化嗜盐古菌进行单菌特性和分子生态学相结合的系统研究。最终通过对多重数据的整合分析，阐明了嗜盐古菌分布、生长条件、表型和基因型特征，在土壤微宇宙和基因组学水平揭示了嗜盐古菌对高盐生态系统中C、N、S等元素的生物地球化学循环具有一定影响，且具有降解氮素污染物、几丁质、酚酸等多样的潜力。本项目明确了嗜盐古菌通过反硝化和DNRA作用主导盐渍土壤中硝酸盐和亚硝酸盐的消除和转移机制。同时，本项目为具有优良性状的嗜盐古菌挖掘提供理论基础，并从表型和基因型的角度对于嗜盐古菌培养和高效筛选等方面给予一定的指导作用。本项目研究对评估盐渍土反硝化潜势及其生态效应、提高盐渍土肥力改良效率、拓展反硝化微生物研究等具有重要意义。