酸性土壤氨氧化古菌耐铝机制研究

Nitrification is mainly driven by ammonia oxidizing archaea (AOA)in the highly acidic soils. Soil AOA can be adapted to high aluminum (Al) condition. Characterization and mechanisms of Al resistance in AOA are still unclear and require further studies. In this study,a new AOA , which isolated from acidic soil, will be used to analyse the realtionships of AOA growth rate to nitrification activity, and active Al content. Aluminum distribution in AOA will be detected by Nano-SIMS and LA-ICP-MS. Ultrastructural changes of AOA caused by Al treatment will be investigated by transmission electron microscope. Meanwhile, biochemical components of the cell wall and membrane will be analysed by HPLC-ICP-MS. Based on the whole genome sequencing, transcriptome data will be also detected. The objective of this project is to understand the physiological, molecular, and genetic mechanisms of Al resistance in AOA, and assist in regulating soil nitrogen cycling, and exploring new Al resistant mechanisms.

氨氧化古菌是酸性土壤中硝化作用的主要驱动者，适应强酸性土壤的富铝环境，其耐铝特性及机理值得深入研究。本项目拟以本课题组新近分离得到的酸性土壤氨氧化古菌为研究对象，明确氨氧化古菌生长速率、硝化活性和活性铝浓度之间的相互关系；采用Nano-SIMS、LA-ICP-MS、HPLC-ICP-MS、透射电镜等测试技术，分析不同铝浓度下氨氧化古菌的形态变化，铝在氨氧化古菌中的亚细胞分布特征，及细胞壁和细胞膜结构组成的变化。在对该氨氧化古菌全基因组测序的基础上，进一步分析氨氧化古菌的转录组学，明确酸性土壤氨氧化古菌的铝适应分子机制，为有效调控土壤氮素循环，深入揭示和发掘新的生物耐铝机理提供科学依据。

氨氧化古菌能适应强酸性土壤环境，其耐铝特性值得深入研究。本项目以本课题组分离得到的酸性土壤氨氧化古菌纯培养Candidatus Nitrosotalea devanaterra（ND2）为研究对象，研究了其耐铝特性，耐铝、耐酸分子机制以及铝毒害机制。通过培养试验，发现ND2能在铝浓度为1 mM条件下生长，说明其具有较高的耐受铝毒害能力。该氨氧化古菌全基因组总计1,598,048 bp，对目前已有报道的耐铝基因与测序结果进行了比对，但都没有在ND2基因组中发现相似基因。对氨氧化古菌耐酸机制的研究发现，高效的阳离子通道、体内质子消耗和独特的细胞膜结构是氨氧化古菌耐酸的主要原因。利用基因芯片技术，研究了不同铝浓度处理下，氮磷功能基因的表达情况，发现铝处理对氮和磷转化相关基因都有一定的影响。