High Oxygen Concentration Increases the Abundance and Activity of Bacterial Rather than Archaeal Nitrifiers in Rice Field Soil
High Oxygen Concentration Increases the Abundance and Activity of Bacterial Rather than Archaeal Nitrifiers in Rice Field Soil
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DOI：
10.1007/s00248-015-0633-4
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发表时间：
2015-11-01
影响因子：
3.6
通讯作者：
Conrad, Ralf
中科院分区：
文献类型：
--
作者：
Ke, Xiubin;Lu, Wei;Conrad, Ralf
氧气被认为是稻田土壤硝化作用的限制因素。然而，人们对硝化微生物群落如何在群落和转录本水平上对不同氧浓度做出反应知之甚少。在这项研究中，从 50 天大的水稻微观世界中收获土壤和根，并在两种氧气浓度：2% O-2 和 20% O-2（环境空气）下培养长达 45 天。硝化速率通过亚硝酸盐和硝酸盐的积累来测量。细菌 (AOB) 和古细菌 (AOA) 氨氧化剂的种群动态是通过其 amoA 基因的丰度（使用定量 PCR (qPCR)）和组成（使用末端限制性片段长度多态性和克隆/测序）来确定的，亚硝酸盐氧化剂 (NOB) 的种群动态是通过量化硝化杆菌属的 nxrA 基因来确定的。和 Nitrospira spp 的 16S rRNA 基因。通过量化 amoA 和 nxrA 转录本的拷贝数（使用 RT-qPCR）来确定硝化菌的活性。不同的氧浓度对AOB、AOA和NOB的群落组成没有影响，但表层土壤、底层土壤和水稻根系的群落组成存在差异。然而，环境空气中的硝化率高于 2% O-2，并且 AOB（而非 AOA）的丰度和转录活性也更高。环境空气中硝化细菌的丰度和转录本拷贝数也较高。这些结果表明，AOB 和 NOB 对氧气可用性敏感，但 AOA 则不然。
Oxygen is considered as a limiting factor for nitrification in rice paddy soil. However, little is known about how the nitrifying microbial community responds to different oxygen concentrations at community and transcript level. In this study, soil and roots were harvested from 50-day-old rice microcosms and were incubated for up to 45 days under two oxygen concentrations: 2 % O-2 and 20 % O-2 (ambient air). Nitrification rates were measured from the accumulation of nitrite plus nitrate. The population dynamics of bacterial (AOB) and archaeal (AOA) ammonia oxidizers was determined from the abundance (using quantitative PCR (qPCR)) and composition (using terminal restriction fragment length polymorphism and cloning/sequencing) of their amoA genes, that of nitrite oxidizers (NOB) by quantifying the nxrA gene of Nitrobacter spp. and the 16S rRNA gene of Nitrospira spp. The activity of the nitrifiers was determined by quantifying the copy numbers of amoA and nxrA transcripts (using RT-qPCR). Different oxygen concentrations did not affect the community compositions of AOB, AOA, and NOB, which however were different between surface soil, bottom soil, and rice roots. However, nitrification rates were higher under ambient air than 2 % O-2, and abundance and transcript activities of AOB, but not of AOA, were also higher. Abundance and transcript copy numbers of Nitrobacter were also higher at ambient air. These results indicate that AOB and NOB, but not AOA, were sensitive to oxygen availability.