Links between ammonia oxidizer species composition, functional diversity and nitrification kinetics in grassland soils.
Links between ammonia oxidizer species composition, functional diversity and nitrification kinetics in grassland soils.
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DOI：
10.1111/j.1462-2920.2005.00740.x
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发表时间：
2005-05
影响因子：
5.1
通讯作者：
G. Webster;T. Embley;Thomas E. Freitag;Zena Smith;J. Prosser
中科院分区：
文献类型：
--
作者：
G. Webster;T. Embley;Thomas E. Freitag;Zena Smith;J. Prosser
分子方法揭示了自然原核生物种群中相当大的多样性和未培养的新颖性，但所检测到的新基因类型与生态系统过程之间没有直接联系。在这里，我们描述了氨氧化细菌群落结构对微生态系统中氮循环的影响，这些微宇宙包括天然和人工管理的草原，并用人工绵羊尿液进行修正，人工绵羊尿液是决定这些环境中当地氨浓度的主要因素。通过分析尿素、氨氮、亚硝酸盐和硝酸盐浓度的变化来评价硝化动力学，通过分析氨氧化剂特异引物从提取的DNA中扩增的16S rRNA基因来表征氨氧化剂群落。在天然土壤中，氨氧化菌群落结构决定了硝化作用前的延迟，这取决于两个亚硝化菌群3a和3b的相对丰度。在分批培养中，Nitrosspira 3a的纯培养和浓缩培养代表对高氨浓度敏感，而Nitrosspira CLUG3b代表和欧洲亚硝酸单胞菌耐受。硝化作用的延迟发生在以亚硝酸螺旋体3a群为主的自然土壤中，这是由于低浓度亚硝酸螺旋体3b群生长所需的时间所致。在以亚硝酸螺旋体3b和亚硝酸单胞菌为主的微宇宙中，没有观察到明显的延迟。在受管理的土壤中，没有检测到硝化作用的延迟，无论初始氨氧化菌群落结构如何，最可能的原因是氨氧化菌细胞浓度较高。因此，这些数据表明细菌群落结构、生理多样性和生态系统功能之间存在直接联系。
Molecular approaches have revealed considerable diversity and uncultured novelty in natural prokaryotic populations, but not direct links between the new genotypes detected and ecosystem processes. Here we describe the influence of the structure of communities of ammonia-oxidizing bacteria on nitrogen cycling in microcosms containing natural and managed grasslands and amended with artificial sheep urine, a major factor determining local ammonia concentrations in these environments. Nitrification kinetics were assessed by analysis of changes in urea, ammonia, nitrite and nitrate concentrations and ammonia oxidizer communities were characterized by analysis of 16S rRNA genes amplified from extracted DNA using ammonia oxidizer-specific primers. In natural soils, ammonia oxidizer community structure determined the delay preceding nitrification, which depended on the relative abundance of two Nitrosospira clusters, termed 3a and 3b. In batch cultures, pure culture and enrichment culture representatives of Nitrosospira 3a were sensitive to high ammonia concentration, while Nitrosospira cluster 3b representatives and Nitrosomonas europaea were tolerant. Delays in nitrification occurred in natural soils dominated by Nitrosospira cluster 3a and resulted from the time required for growth of low concentrations of Nitrosospira cluster 3b. In microcosms dominated by Nitrosospira cluster 3b and Nitrosomonas, no substantial delays were observed. In managed soils, no delays in nitrification were detected, regardless of initial ammonia oxidizer community structure, most probably resulting from higher ammonia oxidizer cell concentrations. The data therefore demonstrate a direct link between bacterial community structure, physiological diversity and ecosystem function.