三亚河红树林表层沉积物中好氧氨氧化微生物的分布特征及潜在硝化速率

氨氧化过程是硝化作用的限速步骤,氨氧化细菌(ammonia-oxidizing bacteria, AOB)和氨氧化古菌(ammonia-oxidizing archaea, AOA)是氨氧化作用的主要驱动者,其分布特征及其对硝化作用的相对贡献是氮素循环的研究热点.采用实时荧光定量PCR技术研究了三亚河红树林表层沉积物中好氧氨氧化微生物的分布特征,并通过测定潜在硝化速率分析了AOB和AOA对硝化作用的相对贡献率.结果表明,多数采样点中,AOA amoA基因丰度高于AOB amoA基因丰度; AOB丰度冬季较高,AOA丰度夏季较高,且冬季AOA和AOB丰度的比值较低;溶解氧、pH、总有机碳和硝态氮对AOB和AOA丰度影响较大; AOB和AOA在夏季的潜在硝化速率均高于冬季,冬季AOA对硝化作用的相对贡献率较高而夏季则是AOB在硝化作用中占主导地位,AOB和AOA的潜在硝化速率与amoA基因丰度均不存在显著相关性.

Distribution and Potential Nitrification Rates of Aerobic Ammonia-Oxidizing Microorganisms in Surface Sediments of Mangrove in Sanya River

The ammonia oxidation process is a rate-limiting step in nitrification. Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are the major drivers of ammonia oxidation. Their distribution and relative contributions to nitrification are the research highlights in the nitrogen cycle. Real-time quantitative polymerase chain reaction (qPCR) was used to study the distribution of aerobic ammonia-oxidizing microorganisms in the surface sediments of mangrove in the Sanya River, and the relative contribution rates of AOB and AOA to nitrification were calculated through the determination of the potential nitrification rates (PNR). The results showed that, in most sampling sites, the abundance of AOA amoA genes was higher than that of AOB amoA genes. The abundance of AOB was higher during the winter, whereas that of AOA was higher during the summer, and the ratio of AOA to AOB abundance was lower during the winter. The dissolved oxygen (DO) content, pH, total organic carbon (TOC) content, and nitrate concentration greatly influenced the abundance of AOB and AOA. The potential nitrification rates of AOB and AOA were both higher during the summer than during the winter, and the relative contribution rate of AOA to nitrification was higher during the winter, whereas that of AOB was higher during the summer. There were no significant correlations between the PNR and amoA genes abundance of AOB and AOA.